1
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Emelianov AV, Pettersson M, Bobrinetskiy II. Ultrafast Laser Processing of 2D Materials: Novel Routes to Advanced Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2402907. [PMID: 38757602 DOI: 10.1002/adma.202402907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/23/2024] [Indexed: 05/18/2024]
Abstract
Ultrafast laser processing has emerged as a versatile technique for modifying materials and introducing novel functionalities. Over the past decade, this method has demonstrated remarkable advantages in the manipulation of 2D layered materials, including synthesis, structuring, functionalization, and local patterning. Unlike continuous-wave and long-pulsed optical methods, ultrafast lasers offer a solution for thermal heating issues. Nonlinear interactions between ultrafast laser pulses and the atomic lattice of 2D materials substantially influence their chemical and physical properties. This paper highlights the transformative role of ultrafast laser pulses in maskless green technology, enabling subtractive, and additive processes that unveil ways for advanced devices. Utilizing the synergetic effect between the energy states within the atomic layers and ultrafast laser irradiation, it is feasible to achieve unprecedented resolutions down to several nanometers. Recent advancements are discussed in functionalization, doping, atomic reconstruction, phase transformation, and 2D and 3D micro- and nanopatterning. A forward-looking perspective on a wide array of applications of 2D materials, along with device fabrication featuring novel physical and chemical properties through direct ultrafast laser writing, is also provided.
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Affiliation(s)
- Aleksei V Emelianov
- Nanoscience Center, Department of Chemistry, University of Jyväskylä, Jyväskylä, FI-40014, Finland
| | - Mika Pettersson
- Nanoscience Center, Department of Chemistry, University of Jyväskylä, Jyväskylä, FI-40014, Finland
| | - Ivan I Bobrinetskiy
- BioSense Institute - Research and Development Institute for Information Technologies in Biosystems, University of Novi Sad, Novi Sad, 21000, Serbia
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2
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Thomson MD, Ludwig F, Holstein J, Al-Mudhafar R, Al-Daffaie S, Roskos HG. Coherent Terahertz Detection via Ultrafast Dynamics of Hot Dirac Fermions in Graphene. ACS NANO 2024; 18:4765-4774. [PMID: 38301137 PMCID: PMC10868588 DOI: 10.1021/acsnano.3c08731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/22/2023] [Accepted: 12/27/2023] [Indexed: 02/03/2024]
Abstract
Graphene has recently been shown to exhibit ultrafast conductivity modulation due to periodic carrier heating by either terahertz (THz) waves, leading to self-induced harmonic generation, or the intensity beat note of two-color optical radiation. We exploit the latter to realize an optoelectronic photomixer for coherent, continuous-wave THz detection, based on a photoconductive antenna with multilayer CVD-grown graphene in the gap. While for biased THz emitters the dark current would pose a serious detriment for performance, we show that this is not the case for bias-free THz detection and demonstrate detection up to frequencies of at least 700 GHz at room temperature, even without optimized tuning of the doping. We account for the photocurrent and photomixing response using detailed simulations of the time-dependent carrier distribution, which also indicate significant potential for enhancement of the sensitivity, to become competitive with well-established semiconductor photomixers.
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Affiliation(s)
- Mark D. Thomson
- Physikalisches
Institut, Johann Wolfgang Goethe-Universität, 60438 Frankfurt
am Main, Germany
| | - Florian Ludwig
- Physikalisches
Institut, Johann Wolfgang Goethe-Universität, 60438 Frankfurt
am Main, Germany
| | - Jakob Holstein
- Physikalisches
Institut, Johann Wolfgang Goethe-Universität, 60438 Frankfurt
am Main, Germany
| | - Reiam Al-Mudhafar
- Physikalisches
Institut, Johann Wolfgang Goethe-Universität, 60438 Frankfurt
am Main, Germany
| | - Shihab Al-Daffaie
- Department
of Electrical Engineering and Center for Terahertz Science and Technology, Eindhoven University of Technology, 5612 AE Eindhoven, Netherlands
| | - Hartmut G. Roskos
- Physikalisches
Institut, Johann Wolfgang Goethe-Universität, 60438 Frankfurt
am Main, Germany
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3
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Odutola J, Szalad H, Albero J, García H, Tkachenko NV. Long-Lived Photo-Response of Multi-Layer N-Doped Graphene-Based Films. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:17896-17905. [PMID: 37736291 PMCID: PMC10510389 DOI: 10.1021/acs.jpcc.3c04670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/17/2023] [Indexed: 09/23/2023]
Abstract
New insights into the mechanism of the improved photo(electro)catalytic activity of graphene by heteroatom doping were explored by transient transmittance and reflectance spectroscopy of multi-layer N-doped graphene-based samples on a quartz substrate prepared by chitosan pyrolysis in the temperature range 900-1200 °C compared to an undoped graphene control. All samples had an expected photo-response: fast relaxation (within 1 ps) due to decreased plasmon damping and increased conductivity. However, the N-doped graphenes had an additional transient absorption signal of roughly 10 times lower intensity, with 10-50 ps formation time and the lifetime extending into the nanosecond domain. These photo-induced responses were recalculated as (complex) dielectric function changes and decomposed into Drude-Lorentz parameters to derive the origin of the opto(electronic) responses. Consequently, the long-lived responses were revealed to have different dielectric function spectra from those of the short-lived responses, which was ultimately attributed to electron trapping at doping centers. These trapped electrons are presumed to be responsible for the improved catalytic activity of multi-layer N-doped graphene-based films compared to that of multi-layer undoped graphene-based films.
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Affiliation(s)
- Jokotadeola
A. Odutola
- Photonics
Compound and Nanomaterials (Chemistry and Advanced Materials Group),
Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, FI-33720 Tampere, Finland
| | - Horatiu Szalad
- Instituto
Universitario de Tecnología Química, Universitat Politècnica de València, Avda. de los Naranjos s/n, 46022 Valencia, Spain
| | - Josep Albero
- Instituto
Universitario de Tecnología Química, Universitat Politècnica de València, Avda. de los Naranjos s/n, 46022 Valencia, Spain
| | - Hermenegildo García
- Instituto
Universitario de Tecnología Química, Universitat Politècnica de València, Avda. de los Naranjos s/n, 46022 Valencia, Spain
| | - Nikolai V. Tkachenko
- Photonics
Compound and Nanomaterials (Chemistry and Advanced Materials Group),
Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, FI-33720 Tampere, Finland
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4
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Fu S, Jia X, Hassan AS, Zhang H, Zheng W, Gao L, Di Virgilio L, Krasel S, Beljonne D, Tielrooij KJ, Bonn M, Wang HI. Reversible Electrical Control of Interfacial Charge Flow across van der Waals Interfaces. NANO LETTERS 2023; 23:1850-1857. [PMID: 36799492 PMCID: PMC9999450 DOI: 10.1021/acs.nanolett.2c04795] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/12/2023] [Indexed: 06/18/2023]
Abstract
Bond-free integration of two-dimensional (2D) materials yields van der Waals (vdW) heterostructures with exotic optical and electronic properties. Manipulating the splitting and recombination of photogenerated electron-hole pairs across the vdW interface is essential for optoelectronic applications. Previous studies have unveiled the critical role of defects in trapping photogenerated charge carriers to modulate the photoconductive gain for photodetection. However, the nature and role of defects in tuning interfacial charge carrier dynamics have remained elusive. Here, we investigate the nonequilibrium charge dynamics at the graphene-WS2 vdW interface under electrochemical gating by operando optical-pump terahertz-probe spectroscopy. We report full control over charge separation states and thus photogating field direction by electrically tuning the defect occupancy. Our results show that electron occupancy of the two in-gap states, presumably originating from sulfur vacancies, can account for the observed rich interfacial charge transfer dynamics and electrically tunable photogating fields, providing microscopic insights for optimizing optoelectronic devices.
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Affiliation(s)
- Shuai Fu
- Max
Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Xiaoyu Jia
- Max
Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Aliaa S. Hassan
- Max
Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Heng Zhang
- Max
Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Wenhao Zheng
- Max
Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Lei Gao
- Max
Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
- School
of Physics and Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 211189, China
| | - Lucia Di Virgilio
- Max
Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Sven Krasel
- Max
Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - David Beljonne
- Laboratory
for Chemistry of Novel Materials, Université
de Mons, 20 Place du
Parc, 7000 Mons, Belgium
| | - Klaas-Jan Tielrooij
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), BIST & CSIC, Campus UAB, Bellaterra, Barcelona 08193, Spain
| | - Mischa Bonn
- Max
Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Hai I. Wang
- Max
Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
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5
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Li G, Wang G, Yang T, Zhang Y, Shen J, Zhang B. Graphene-based terahertz bias-driven negative-conductivity metasurface. NANOSCALE ADVANCES 2022; 4:3342-3352. [PMID: 36131710 PMCID: PMC9417548 DOI: 10.1039/d2na00288d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/30/2022] [Indexed: 06/15/2023]
Abstract
A graphene-based terahertz negative-conductivity metasurface based on two types of unit cell structures is investigated under the control of an external bias voltage. Electrical characterization is conducted and verification is performed using a finite-difference time-domain (FDTD) and an optical-pump terahertz (THz)-probe system in terms of simulation and transient response analysis. Owing to the metal-like properties of graphene, a strong interaction between the metasurface and monolayer graphene yields a short-circuit effect, which considerably weakens the intensity of the resonance mode under passive conditions. Under active conditions, graphene, as an active load, actively induces a negative-conductivity effect, which enhances the THz transmission and recovers the resonance intensity gradually because of the weakening of the short-circuit effect. The resulting resonance frequency shows a blue shift. This study provides a reference value for combining graphene exhibiting the terahertz bias-driven negative-conductivity effect with metasurfaces and its corresponding applications in the future.
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Affiliation(s)
- Guibin Li
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Advanced Innovation Center for Imaging Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University Beijing 100048 China
| | - Guocui Wang
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Advanced Innovation Center for Imaging Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University Beijing 100048 China
| | - Tingting Yang
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Advanced Innovation Center for Imaging Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University Beijing 100048 China
| | - Yan Zhang
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Advanced Innovation Center for Imaging Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University Beijing 100048 China
| | - Jingling Shen
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Advanced Innovation Center for Imaging Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University Beijing 100048 China
| | - Bo Zhang
- Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Advanced Innovation Center for Imaging Technology, Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Beijing Key Laboratory of Metamaterials and Devices, Department of Physics, Capital Normal University Beijing 100048 China
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6
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Xing X, Zhang Z, Quan C, Zhao L, Wang C, Jia T, Ren J, Du J, Leng Y. Tunable ultrafast electron transfer in WSe 2-graphene heterostructures enabled by atomic stacking order. NANOSCALE 2022; 14:7418-7425. [PMID: 35543212 DOI: 10.1039/d1nr07698a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Efficient interfacial light-electric interconversion in van der Waals (vdW) heterostructures is crucial for their optoelectronic applications. However, an in-depth understanding of the necessary process for device operation, namely interfacial charge transfer (CT), has thus far remained elusive. In this study, by using photon energy-dependent transient THz spectroscopy, we complementarily investigate the interfacial CT process in heterostructures comprising monolayers of WSe2 and graphene with varying stacking orders on a sapphire substrate. We observe that the CT mechanism of the sub-A-exciton excitation is different from that of the above-A-exciton excitation. Notably, the CT process occurs via a photo-thermionic emission for sub-A-exciton excitations and a direct electron (or hole) transfer for above-A-exciton excitations. Furthermore, we demonstrate that the effective electric field induced by the sapphire substrate could adjust the Schottky barrier from a p-type contact (WSe2/Gr/sapphire) to an n-type contact (Gr/WSe2/sapphire). Consequently, it is more beneficial for the photo-thermionic electrons to transfer from graphene to WSe2 over the Schottky barrier in Gr/WSe2/sapphire. These results can provide new insights into the CT process in graphene-transition metal dichalcogenide (TMDC) vdW interfaces, which are critical to potential optoelectronic applications of graphene-TMDC heterostructures.
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Affiliation(s)
- Xiao Xing
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
| | - Zeyu Zhang
- Hangzhou Institute for Advanced Study and Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Hangzhou 310024, China.
| | - Chenjing Quan
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
- School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - Litao Zhao
- Key Laboratory of Spin Electron and Nanomaterials of Anhui Higher Education Institutes, Suzhou University, Suzhou 234000, People's Republic of China
| | - Chunwei Wang
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
| | - Tingyuan Jia
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
| | - Junfeng Ren
- School of Physics and Electronics, Shandong Normal University, Jinan, 250014, China
| | - Juan Du
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
- Hangzhou Institute for Advanced Study and Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Hangzhou 310024, China.
| | - Yuxin Leng
- State Key Laboratory of High Field Laser Physics and CAS Center for Excellence in Ultra-intense Laser Science, Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), Shanghai 201800, China.
- Hangzhou Institute for Advanced Study and Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Hangzhou 310024, China.
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7
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Yu X, Fu S, Mandal M, Yao X, Liu Z, Zheng W, Samorì P, Narita A, Müllen K, Andrienko D, Bonn M, Wang HI. Tuning Interfacial Charge Transfer in Atomically Precise Nanographene-Graphene Heterostructures by Engineering van der Waals Interactions. J Chem Phys 2022; 156:074702. [DOI: 10.1063/5.0081074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Xiaoqing Yu
- Max-Plank Institute for Polymer Research, Germany
| | | | | | - Xuelin Yao
- Max-Plank Institute for Polymer Research, Germany
| | | | - Wenhao Zheng
- Max-Plank Institute for Polymer Research, Germany
| | | | - Akimitsu Narita
- Okinawa Institute of Science and Technology Graduate University, Japan
| | | | | | - Mischa Bonn
- Max-Plank Institute for Polymer Research, Germany
| | - Hai I. Wang
- Molecular spectroscopy, Max Planck Institute for Polymer Research, Germany
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8
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Hu F, Chen S, Wang R, Meng Y, Liu Q, Gong M. Tunable extreme energy transfer of terahertz waves with graphene in a nested cavity. OPTICS EXPRESS 2021; 29:34302-34313. [PMID: 34809224 DOI: 10.1364/oe.435044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/26/2021] [Indexed: 06/13/2023]
Abstract
Energy transfer is an essential light-matter interaction. The transfer efficiency is critical for various applications such as light-emitting, optical modulation, and the photoelectric effect. Two primary forms of light-matter energy transfer, including absorption and emission, can be enhanced in optical cavities. Both forms can reach an extremum inside the cavity according to the coupled-mode theory. Graphene conductivity at the terahertz frequency can be tuned from positive to negative, providing a suitable material to study switchable extremums of these two forms. We integrate graphene with a nested cavity where an infrared cavity is inserted in a terahertz cavity, thereby achieving terahertz perfect absorption at the static state and optimal gain under photoexcitation. Leveraging an inserted infrared cavity, we can elevate the working efficiency by strongly absorbing the infrared pump. We also numerically show the feasibility of electrically tunable extreme energy transfer. Our concept of the nested cavity can be extended to different materials and even to guided modes. A switchable synergy of loss and gain potentially enables high-contrast dynamic modulation and photonic devices with multiplexing functions.
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9
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Kim L, Kim S, Jha PK, Brar VW, Atwater HA. Mid-infrared radiative emission from bright hot plasmons in graphene. NATURE MATERIALS 2021; 20:805-811. [PMID: 33795847 DOI: 10.1038/s41563-021-00935-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 01/18/2021] [Indexed: 06/12/2023]
Abstract
Carrier excitation and decay processes in graphene are of broad interest since relaxation pathways that are not present in conventional materials are enabled by a gapless Dirac electronic band structure. Here, we report that a previously unobserved decay pathway-hot plasmon emission-results in Fermi-level-dependent mid-infrared emission in graphene. Our observations of non-thermal contributions to Fermi-level-dependent radiation are an experimental demonstration of hot plasmon emission arising from a photo-inverted carrier distribution in graphene achieved via ultrafast optical excitation. Our calculations indicate that the reported plasmon emission process can be several orders of magnitude brighter than Planckian emission mechanisms in the mid-infrared spectral range. Both the use of gold nanodisks to promote scattering and localized plasmon excitation and polarization-dependent excitation measurements provide further evidence for bright hot plasmon emission. These findings define an approach for future work on ultrafast and ultrabright graphene emission processes and mid-infrared light source applications.
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Affiliation(s)
- Laura Kim
- Thomas J. Watson of Applied Physics, California Institute of Technology, Pasadena, CA, USA
| | - Seyoon Kim
- Thomas J. Watson of Applied Physics, California Institute of Technology, Pasadena, CA, USA
- Department of Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Pankaj K Jha
- Thomas J. Watson of Applied Physics, California Institute of Technology, Pasadena, CA, USA
| | - Victor W Brar
- Thomas J. Watson of Applied Physics, California Institute of Technology, Pasadena, CA, USA.
- Department of Physics, University of Wisconsin-Madison, Madison, WI, USA.
- Kavli Nanoscience Institute, California Institute of Technology, Pasadena, CA, USA.
| | - Harry A Atwater
- Thomas J. Watson of Applied Physics, California Institute of Technology, Pasadena, CA, USA.
- Kavli Nanoscience Institute, California Institute of Technology, Pasadena, CA, USA.
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10
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Lattice Vibrations and Time-Dependent Evolution of Local Phonon Modes during Exciton Formation in Conjugated Polymeric Molecules. Polymers (Basel) 2021; 13:polym13111724. [PMID: 34070250 PMCID: PMC8197373 DOI: 10.3390/polym13111724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/17/2021] [Accepted: 05/18/2021] [Indexed: 12/29/2022] Open
Abstract
Based on nonadiabatic molecular dynamics that integrate electronic transitions with the time-dependent phonon spectrum, this article provides a panoramic landscape of the dynamical process during the formation of photoinduced excitons in conjugated polymers. When external optical beam/pulses with intensities of 10 µJ/cm2 and 20 µJ/cm2 are utilized to excite a conjugated polymer, it is found that the electronic transition firstly triggers local lattice vibrations, which not only locally distort alternating bonds but change the phonon spectrum as well. Within the first 60 fs, the occurrence of local distortion of alternating bonds accompanies the localization of the excited-state’s electron. Up to 100 fs, both alternating bonds and the excited electronic state are well localized in the middle of the polymer chain. In the first ~200 fs, the strong lattice vibration makes a local phonon mode at 1097.7 cm−1 appear in the phonon spectrum. The change of electron states then induces the self-trapping effect to act on the following photoexcitation process of 1.2 ps. During the following relaxation of 1.0 ps, new local infrared phonon modes begin to occur. All of this, incorporated with the occurrence of local infrared phonon modes and localized electronic states at the end of the relaxation, results in completed exciton formation.
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11
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Massicotte M, Soavi G, Principi A, Tielrooij KJ. Hot carriers in graphene - fundamentals and applications. NANOSCALE 2021; 13:8376-8411. [PMID: 33913956 PMCID: PMC8118204 DOI: 10.1039/d0nr09166a] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 03/30/2021] [Indexed: 05/15/2023]
Abstract
Hot charge carriers in graphene exhibit fascinating physical phenomena, whose understanding has improved greatly over the past decade. They have distinctly different physical properties compared to, for example, hot carriers in conventional metals. This is predominantly the result of graphene's linear energy-momentum dispersion, its phonon properties, its all-interface character, and the tunability of its carrier density down to very small values, and from electron- to hole-doping. Since a few years, we have witnessed an increasing interest in technological applications enabled by hot carriers in graphene. Of particular interest are optical and optoelectronic applications, where hot carriers are used to detect (photodetection), convert (nonlinear photonics), or emit (luminescence) light. Graphene-enabled systems in these application areas could find widespread use and have a disruptive impact, for example in the field of data communication, high-frequency electronics, and industrial quality control. The aim of this review is to provide an overview of the most relevant physics and working principles that are relevant for applications exploiting hot carriers in graphene.
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Affiliation(s)
- Mathieu Massicotte
- Institut Quantique and Département de Physique, Université de SherbrookeSherbrookeQuébecCanada
| | - Giancarlo Soavi
- Institute of Solid State Physics, Friedrich Schiller University Jena07743 JenaGermany
- Abbe Center of Photonics, Friedrich Schiller University Jena07745 JenaGermany
| | | | - Klaas-Jan Tielrooij
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST & CSIC, Campus UAB08193BellaterraBarcelonaSpain
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12
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Optoelectronic mixing with high-frequency graphene transistors. Nat Commun 2021; 12:2728. [PMID: 33980859 PMCID: PMC8115296 DOI: 10.1038/s41467-021-22943-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 03/29/2021] [Indexed: 02/03/2023] Open
Abstract
Graphene is ideally suited for optoelectronics. It offers absorption at telecom wavelengths, high-frequency operation and CMOS-compatibility. We show how high speed optoelectronic mixing can be achieved with high frequency (~20 GHz bandwidth) graphene field effect transistors (GFETs). These devices mix an electrical signal injected into the GFET gate and a modulated optical signal onto a single layer graphene (SLG) channel. The photodetection mechanism and the resulting photocurrent sign depend on the SLG Fermi level (EF). At low EF (<130 meV), a positive photocurrent is generated, while at large EF (>130 meV), a negative photobolometric current appears. This allows our devices to operate up to at least 67 GHz. Our results pave the way for GFETs optoelectronic mixers for mm-wave applications, such as telecommunications and radio/light detection and ranging (RADAR/LIDARs.).
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13
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Kovalev S, Hafez HA, Tielrooij KJ, Deinert JC, Ilyakov I, Awari N, Alcaraz D, Soundarapandian K, Saleta D, Germanskiy S, Chen M, Bawatna M, Green B, Koppens FHL, Mittendorff M, Bonn M, Gensch M, Turchinovich D. Electrical tunability of terahertz nonlinearity in graphene. SCIENCE ADVANCES 2021; 7:7/15/eabf9809. [PMID: 33827824 PMCID: PMC8026126 DOI: 10.1126/sciadv.abf9809] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 02/19/2021] [Indexed: 05/25/2023]
Abstract
Graphene is conceivably the most nonlinear optoelectronic material we know. Its nonlinear optical coefficients in the terahertz frequency range surpass those of other materials by many orders of magnitude. Here, we show that the terahertz nonlinearity of graphene, both for ultrashort single-cycle and quasi-monochromatic multicycle input terahertz signals, can be efficiently controlled using electrical gating, with gating voltages as low as a few volts. For example, optimal electrical gating enhances the power conversion efficiency in terahertz third-harmonic generation in graphene by about two orders of magnitude. Our experimental results are in quantitative agreement with a physical model of the graphene nonlinearity, describing the time-dependent thermodynamic balance maintained within the electronic population of graphene during interaction with ultrafast electric fields. Our results can serve as a basis for straightforward and accurate design of devices and applications for efficient electronic signal processing in graphene at ultrahigh frequencies.
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Affiliation(s)
- Sergey Kovalev
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Hassan A Hafez
- Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany.
| | - Klaas-Jan Tielrooij
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST and CSIC, Campus UAB, 08193, Bellaterra (Barcelona), Spain
| | - Jan-Christoph Deinert
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Igor Ilyakov
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Nilesh Awari
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - David Alcaraz
- Institut de Ciencies Fotoniques (ICFO), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | | | - David Saleta
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST and CSIC, Campus UAB, 08193, Bellaterra (Barcelona), Spain
| | - Semyon Germanskiy
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Min Chen
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Mohammed Bawatna
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Bertram Green
- Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Frank H L Koppens
- Institut de Ciencies Fotoniques (ICFO), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Institució Catalana de Recerça i Estudis Avancats (ICREA), 08010 Barcelona, Spain
| | - Martin Mittendorff
- Fakultät für Physik, Universität Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany
| | - Mischa Bonn
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - Michael Gensch
- Institut für Optische Sensorsysteme, DLR, Rutherfordstraße 2, 12489 Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Dmitry Turchinovich
- Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany.
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14
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Fu S, du Fossé I, Jia X, Xu J, Yu X, Zhang H, Zheng W, Krasel S, Chen Z, Wang ZM, Tielrooij KJ, Bonn M, Houtepen AJ, Wang HI. Long-lived charge separation following pump-wavelength-dependent ultrafast charge transfer in graphene/WS 2 heterostructures. SCIENCE ADVANCES 2021; 7:7/9/eabd9061. [PMID: 33637529 PMCID: PMC7909886 DOI: 10.1126/sciadv.abd9061] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 01/12/2021] [Indexed: 05/27/2023]
Abstract
Van der Waals heterostructures consisting of graphene and transition metal dichalcogenides have shown great promise for optoelectronic applications. However, an in-depth understanding of the critical processes for device operation, namely, interfacial charge transfer (CT) and recombination, has so far remained elusive. Here, we investigate these processes in graphene-WS2 heterostructures by complementarily probing the ultrafast terahertz photoconductivity in graphene and the transient absorption dynamics in WS2 following photoexcitation. We observe that separated charges in the heterostructure following CT live extremely long: beyond 1 ns, in contrast to ~1 ps charge separation reported in previous studies. This leads to efficient photogating of graphene. Furthermore, for the CT process across graphene-WS2 interfaces, we find that it occurs via photo-thermionic emission for sub-A-exciton excitations and direct hole transfer from WS2 to the valence band of graphene for above-A-exciton excitations. These findings provide insights to further optimize the performance of optoelectronic devices, in particular photodetection.
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Affiliation(s)
- Shuai Fu
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Indy du Fossé
- Optoelectronic Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, Netherlands
| | - Xiaoyu Jia
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Jingyin Xu
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
| | - Xiaoqing Yu
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Heng Zhang
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Wenhao Zheng
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Sven Krasel
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Zongping Chen
- School of Materials Science and Engineering, Zhejiang University, Zheda Road 38, Hangzhou 310027, China
| | - Zhiming M Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
| | - Klaas-Jan Tielrooij
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), BIST and CSIC, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
| | - Arjan J Houtepen
- Optoelectronic Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, Netherlands
| | - Hai I Wang
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
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15
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Deinert JC, Alcaraz Iranzo D, Pérez R, Jia X, Hafez HA, Ilyakov I, Awari N, Chen M, Bawatna M, Ponomaryov AN, Germanskiy S, Bonn M, Koppens FH, Turchinovich D, Gensch M, Kovalev S, Tielrooij KJ. Grating-Graphene Metamaterial as a Platform for Terahertz Nonlinear Photonics. ACS NANO 2021; 15:1145-1154. [PMID: 33306364 PMCID: PMC7844822 DOI: 10.1021/acsnano.0c08106] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 11/25/2020] [Indexed: 05/23/2023]
Abstract
Nonlinear optics is an increasingly important field for scientific and technological applications, owing to its relevance and potential for optical and optoelectronic technologies. Currently, there is an active search for suitable nonlinear material systems with efficient conversion and a small material footprint. Ideally, the material system should allow for chip integration and room-temperature operation. Two-dimensional materials are highly interesting in this regard. Particularly promising is graphene, which has demonstrated an exceptionally large nonlinearity in the terahertz regime. Yet, the light-matter interaction length in two-dimensional materials is inherently minimal, thus limiting the overall nonlinear optical conversion efficiency. Here, we overcome this challenge using a metamaterial platform that combines graphene with a photonic grating structure providing field enhancement. We measure terahertz third-harmonic generation in this metamaterial and obtain an effective third-order nonlinear susceptibility with a magnitude as large as 3 × 10-8 m2/V2, or 21 esu, for a fundamental frequency of 0.7 THz. This nonlinearity is 50 times larger than what we obtain for graphene without grating. Such an enhancement corresponds to a third-harmonic signal with an intensity that is 3 orders of magnitude larger due to the grating. Moreover, we demonstrate a field conversion efficiency for the third harmonic of up to ∼1% using a moderate field strength of ∼30 kV/cm. Finally, we show that harmonics beyond the third are enhanced even more strongly, allowing us to observe signatures of up to the ninth harmonic. Grating-graphene metamaterials thus constitute an outstanding platform for commercially viable, CMOS-compatible, room-temperature, chip-integrated, THz nonlinear conversion applications.
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Affiliation(s)
| | - David Alcaraz Iranzo
- ICFO
- Institut de Ciències Fotòniques, The
Barcelona Institute of Science and Technology, Castelldefels (Barcelona) 08860, Spain
| | - Raúl Pérez
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), BIST
& CSIC, Campus UAB, Bellaterra
(Barcelona) 08193, Spain
| | - Xiaoyu Jia
- Max-Planck-Institut
für Polymerforschung, Mainz 55128, Germany
| | - Hassan A. Hafez
- Fakultät
für Physik, Universität Bielefeld, Bielefeld 33615, Germany
| | - Igor Ilyakov
- Helmholtz-Zentrum
Dresden-Rossendorf, Dresden 01328, Germany
| | - Nilesh Awari
- Helmholtz-Zentrum
Dresden-Rossendorf, Dresden 01328, Germany
| | - Min Chen
- Helmholtz-Zentrum
Dresden-Rossendorf, Dresden 01328, Germany
| | | | | | | | - Mischa Bonn
- Max-Planck-Institut
für Polymerforschung, Mainz 55128, Germany
| | - Frank H.L. Koppens
- ICFO
- Institut de Ciències Fotòniques, The
Barcelona Institute of Science and Technology, Castelldefels (Barcelona) 08860, Spain
- ICREA
- Institució Catalana de Reçerca i Estudis Avancats, Barcelona 08010, Spain
| | | | - Michael Gensch
- Institute
of Optical Sensor Systems, DLR, Berlin 12489, Germany
- Institut
für Optik und Atomare Physik, Technische
Universität Berlin, Berlin 10623, Germany
| | - Sergey Kovalev
- Helmholtz-Zentrum
Dresden-Rossendorf, Dresden 01328, Germany
| | - Klaas-Jan Tielrooij
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), BIST
& CSIC, Campus UAB, Bellaterra
(Barcelona) 08193, Spain
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16
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Lin Z, Chen J, Zhang Y, Shen J, Li S, George TF. Charge Accumulation of Amplified Spontaneous Emission in a Conjugated Polymer Chain and Its Dynamical Phonon Spectra. Molecules 2020; 25:molecules25133003. [PMID: 32630062 PMCID: PMC7412338 DOI: 10.3390/molecules25133003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/04/2020] [Accepted: 06/09/2020] [Indexed: 11/16/2022] Open
Abstract
In this article, the detailed photoexcitation dynamics which combines nonadiabatic molecular dynamics with electronic transitions shows the occurrence of amplified spontaneous emission (ASE) in conjugated polymers, accompanied by spontaneous electric polarization. The elaborate molecular dynamic process of ultrafast photoexcitation can be described as follows: Continuous external optical pumping (laser of 70 µJ/cm2) not only triggers the appearance of an instantaneous four-level electronic structure but causes population inversion for ASE as well. At the same time, the phonon spectrum of the conjugated polymer changes, and five local infrared lattice vibrational modes form at the two ends, which break the original symmetry in the system and leads to charge accumulation at the ends of the polymer chain without an external electric field. This novel phenomenon gives a brand-new avenue to explain how the lattice vibrations play a role in the evolution of the stimulated emission, which leads to an ultrafast effect in solid conjugated polymers.
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Affiliation(s)
- Zhe Lin
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China; (Z.L.); (Y.Z.)
- Department of Physics, Zhejiang Normal University, Jinhua 321004, China; (J.C.); (J.S.); (S.L.)
| | - Jiahao Chen
- Department of Physics, Zhejiang Normal University, Jinhua 321004, China; (J.C.); (J.S.); (S.L.)
| | - Yusong Zhang
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China; (Z.L.); (Y.Z.)
- Department of Physics, Zhejiang Normal University, Jinhua 321004, China; (J.C.); (J.S.); (S.L.)
| | - Jianguo Shen
- Department of Physics, Zhejiang Normal University, Jinhua 321004, China; (J.C.); (J.S.); (S.L.)
| | - Sheng Li
- Department of Physics, Zhejiang Normal University, Jinhua 321004, China; (J.C.); (J.S.); (S.L.)
| | - Thomas F. George
- Department of Physics, Zhejiang Normal University, Jinhua 321004, China; (J.C.); (J.S.); (S.L.)
- Department of Chemistry &Biochemistry and Physics & Astronomy, University of Missouri–St. Louis, St. Louis, MO 63121, USA
- Correspondence:
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17
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Li G, Amer N, Hafez HA, Huang S, Turchinovich D, Mochalin VN, Hegmann FA, Titova LV. Dynamical Control over Terahertz Electromagnetic Interference Shielding with 2D Ti 3C 2T y MXene by Ultrafast Optical Pulses. NANO LETTERS 2020; 20:636-643. [PMID: 31825625 DOI: 10.1021/acs.nanolett.9b04404] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
High electrical conductivity and strong absorption of electromagnetic radiation in the terahertz (THz) frequency range by metallic 2D MXene Ti3C2Ty make it a promising material for electromagnetic interference shielding, THz detectors, and transparent conducting electrodes. Here, we demonstrate that ultrafast optical pulses with wavelengths straddling the visible range (400 and 800 nm) induce transient broad-band THz transparency in the MXene that persists for nanoseconds. We demonstrate that optically induced transient THz transparency is independent of temperature from 95 to 290 K. This discovery opens new possibilities for development of switchable electromagnetic interference shielding materials and devices that can be rendered partially transparent on demand for transmitting THz signals, or for designing new THz devices such as sensitive optically gated detectors.
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Affiliation(s)
- Guangjiang Li
- Department of Physics , Worcester Polytechnic Institute , Worcester , Massachusetts 01609 , United States
| | - Naaman Amer
- Department of Physics , University of Alberta , Edmonton , AB T6G 2E1 , Canada
| | - Hassan A Hafez
- Fakultät für Physik, Universität Bielefeld , 33615 Bielefeld , Germany
| | - Shuohan Huang
- Department of Chemistry , Missouri University of Science & Technology , Rolla , Missouri 65409 , United States
| | | | - Vadym N Mochalin
- Department of Chemistry , Missouri University of Science & Technology , Rolla , Missouri 65409 , United States
- Department of Materials Science & Engineering , Missouri University of Science & Technology , Rolla , Missouri 65409 , United States
| | - Frank A Hegmann
- Department of Physics , University of Alberta , Edmonton , AB T6G 2E1 , Canada
| | - Lyubov V Titova
- Department of Physics , Worcester Polytechnic Institute , Worcester , Massachusetts 01609 , United States
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18
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Jia X, Hu M, Soundarapandian K, Yu X, Liu Z, Chen Z, Narita A, Müllen K, Koppens FHL, Jiang J, Tielrooij KJ, Bonn M, Wang HI. Kinetic Ionic Permeation and Interfacial Doping of Supported Graphene. NANO LETTERS 2019; 19:9029-9036. [PMID: 31742413 PMCID: PMC6909232 DOI: 10.1021/acs.nanolett.9b04053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 11/08/2019] [Indexed: 05/31/2023]
Abstract
Due to its outstanding electrical properties and chemical stability, graphene finds widespread use in various electrochemical applications. Although the presence of electrolytes strongly affects its electrical conductivity, the underlying mechanism has remained elusive. Here, we employ terahertz spectroscopy as a contact-free means to investigate the impact of ubiquitous cations (Li+, Na+, K+, and Ca2+) in aqueous solution on the electronic properties of SiO2-supported graphene. We find that, without applying any external potential, cations can shift the Fermi energy of initially hole-doped graphene by ∼200 meV up to the Dirac point, thus counteracting the initial substrate-induced hole doping. Remarkably, the cation concentration and cation hydration complex size determine the kinetics and magnitude of this shift in the Fermi level. Combined with theoretical calculations, we show that the ion-induced Fermi level shift of graphene involves cationic permeation through graphene. The interfacial cations located between graphene and SiO2 electrostatically counteract the substrate-induced hole doping effect in graphene. These insights are crucial for graphene device processing and further developing graphene as an ion-sensing material.
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Affiliation(s)
- Xiaoyu Jia
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- The
Graduate School of Excellence Materials Science in Mainz, University of Mainz, Staudingerweg 9, 55128 Mainz, Germany
| | - Min Hu
- Hefei
National Laboratory for Physical Sciences at the Microscale, iChEM
(Collaborative Innovation Center of Chemistry for Energy Materials),
CAS Center for Excellence in Nanoscience, School of Chemistry and
Materials Science, University of Science
and Technology of China, Hefei, Anhui 230026, China
| | - Karuppasamy Soundarapandian
- ICFO
- Institut de Ciéncies Fotóniques, Mediterranean Technology Park, Castelldefels, Barcelona 08860, Spain
| | - Xiaoqing Yu
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Zhaoyang Liu
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Zongping Chen
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Akimitsu Narita
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Klaus Müllen
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Frank H. L. Koppens
- ICFO
- Institut de Ciéncies Fotóniques, Mediterranean Technology Park, Castelldefels, Barcelona 08860, Spain
| | - Jun Jiang
- Hefei
National Laboratory for Physical Sciences at the Microscale, iChEM
(Collaborative Innovation Center of Chemistry for Energy Materials),
CAS Center for Excellence in Nanoscience, School of Chemistry and
Materials Science, University of Science
and Technology of China, Hefei, Anhui 230026, China
| | - Klaas-Jan Tielrooij
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), BIST and CSIC, Campus UAB, Bellaterra, Barcelona 08193, Spain
| | - Mischa Bonn
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Hai I. Wang
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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19
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Jnawali G, Linser S, Shojaei IA, Pournia S, Jackson HE, Smith LM, Need RF, Wilson SD. Revealing Optical Transitions and Carrier Recombination Dynamics within the Bulk Band Structure of Bi 2Se 3. NANO LETTERS 2018; 18:5875-5884. [PMID: 30106301 DOI: 10.1021/acs.nanolett.8b02577] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Bismuth selenide (Bi2Se3) is a prototypical 3D topological insulator whose Dirac surface states have been extensively studied theoretically and experimentally. Surprisingly little, however, is known about the energetics and dynamics of electrons and holes within the bulk band structure of the semiconductor. We use mid-infrared femtosecond transient reflectance measurements on a single nanoflake to study the ultrafast thermalization and recombination dynamics of photoexcited electrons and holes within the extended bulk band structure over a wide energy range (0.3 to 1.2 eV). Theoretical modeling of the reflectivity spectral line shapes at 10 K demonstrates that the electrons and holes are photoexcited within a dense and cold electron gas with a Fermi level positioned well above the bottom of the lowest conduction band. Direct optical transitions from the first and the second spin-orbit split valence bands to the Fermi level above the lowest conduction band minimum are identified. The photoexcited carriers thermalize rapidly to the lattice temperature within a couple of picoseconds due to optical phonon emission and scattering with the cold electron gas. The minority carrier holes recombine with the dense electron gas within 150 ps at 10 K and 50 ps at 300 K. Such knowledge of interaction of electrons and holes within the bulk band structure provides a foundation for understanding how such states interact dynamically with the topologically protected Dirac surface states.
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Affiliation(s)
- Giriraj Jnawali
- Department of Physics , University of Cincinnati , Cincinnati , Ohio 45221 , United States
| | - Samuel Linser
- Department of Physics , University of Cincinnati , Cincinnati , Ohio 45221 , United States
| | - Iraj Abbasian Shojaei
- Department of Physics , University of Cincinnati , Cincinnati , Ohio 45221 , United States
| | - Seyyedesadaf Pournia
- Department of Physics , University of Cincinnati , Cincinnati , Ohio 45221 , United States
| | - Howard E Jackson
- Department of Physics , University of Cincinnati , Cincinnati , Ohio 45221 , United States
| | - Leigh M Smith
- Department of Physics , University of Cincinnati , Cincinnati , Ohio 45221 , United States
| | - Ryan F Need
- Materials Department , University of California , Santa Barbara , California 93106 , United States
| | - Stephen D Wilson
- Materials Department , University of California , Santa Barbara , California 93106 , United States
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20
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Kar S, Mohapatra DR, Sood AK. Tunable terahertz photoconductivity of hydrogen functionalized graphene using optical pump-terahertz probe spectroscopy. NANOSCALE 2018; 10:14321-14330. [PMID: 30020299 DOI: 10.1039/c8nr04154g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We show that the terahertz photoconductivity of monolayer graphene following 800 nm femtosecond optical pump excitation can be tuned by different levels of hydrogenation (graphane) and provide a quantitative understanding of the unique spectral dependence of photoconductivity. The real part of terahertz photoconductivity (ΔσRe(ω)), which is negative in doped pristine graphene, becomes positive after hydrogenation. Frequency and electronic temperature Te dependent conductivity σ(ω, Te) is calculated using the Boltzmann transport equation taking into account the energy dependence of different scattering rates of the hot carriers. It is shown that the carrier scattering rate dominated by disorder-induced short-range scattering, though sufficient for pristine graphene, is not able to explain the observed complex Δσ(ω) for graphane. Our results are explained by considering the system to be heterogeneous after hydrogenation where conductivity is a weighted sum of conductivities of two parts: one dominated by Coulomb scattering coming from trapped charge impurities in the underlying substrate and the other dominated by short-range scattering coming from disorder, surface defects, dislocations and ripples in graphene flakes. A finite band gap opening due to hydrogenation is shown to be important in determining Δσ(ω).
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Affiliation(s)
- Srabani Kar
- Department of Physics, Indian Institute of Science, Bangalore 560 012, India. and Center for ultrafast laser application, Indian Institute of Science, Bangalore 560 012, India
| | - Dipti R Mohapatra
- Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
| | - A K Sood
- Department of Physics, Indian Institute of Science, Bangalore 560 012, India. and Center for ultrafast laser application, Indian Institute of Science, Bangalore 560 012, India
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21
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Tomadin A, Hornett SM, Wang HI, Alexeev EM, Candini A, Coletti C, Turchinovich D, Kläui M, Bonn M, Koppens FHL, Hendry E, Polini M, Tielrooij KJ. The ultrafast dynamics and conductivity of photoexcited graphene at different Fermi energies. SCIENCE ADVANCES 2018; 4:eaar5313. [PMID: 29756035 PMCID: PMC5947979 DOI: 10.1126/sciadv.aar5313] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 03/23/2018] [Indexed: 05/06/2023]
Abstract
For many of the envisioned optoelectronic applications of graphene, it is crucial to understand the subpicosecond carrier dynamics immediately following photoexcitation and the effect of photoexcitation on the electrical conductivity-the photoconductivity. Whereas these topics have been studied using various ultrafast experiments and theoretical approaches, controversial and incomplete explanations concerning the sign of the photoconductivity, the occurrence and significance of the creation of additional electron-hole pairs, and, in particular, how the relevant processes depend on Fermi energy have been put forward. We present a unified and intuitive physical picture of the ultrafast carrier dynamics and the photoconductivity, combining optical pump-terahertz probe measurements on a gate-tunable graphene device, with numerical calculations using the Boltzmann equation. We distinguish two types of ultrafast photo-induced carrier heating processes: At low (equilibrium) Fermi energy (EF ≲ 0.1 eV for our experiments), broadening of the carrier distribution involves interband transitions (interband heating). At higher Fermi energy (EF ≳ 0.15 eV), broadening of the carrier distribution involves intraband transitions (intraband heating). Under certain conditions, additional electron-hole pairs can be created [carrier multiplication (CM)] for low EF, and hot carriers (hot-CM) for higher EF. The resultant photoconductivity is positive (negative) for low (high) EF, which in our physical picture, is explained using solely electronic effects: It follows from the effect of the heated carrier distributions on the screening of impurities, consistent with the DC conductivity being mostly due to impurity scattering. The importance of these insights is highlighted by a discussion of the implications for graphene photodetector applications.
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Affiliation(s)
- Andrea Tomadin
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genova, Italy
- Corresponding author. (K.-J.T.); (A.T.)
| | - Sam M. Hornett
- School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Hai I. Wang
- Institute of Physics, Johannes Gutenberg University Mainz, 55099 Mainz, Germany
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | | | - Andrea Candini
- Centro S3, Istituto Nanoscienze-CNR, via Campi 213/a 41125 Modena, Italy
| | - Camilla Coletti
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genova, Italy
- Center for Nanotechnology Innovation at NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Dmitry Turchinovich
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
- Fakultät für Physik, Universität Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany
| | - Mathias Kläui
- Institute of Physics, Johannes Gutenberg University Mainz, 55099 Mainz, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Frank H. L. Koppens
- ICFO - Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
- ICREA - Institució Catalana de Reçerca i Estudis Avancats, 08010 Barcelona, Spain
| | - Euan Hendry
- School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Marco Polini
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genova, Italy
| | - Klaas-Jan Tielrooij
- ICFO - Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona 08860, Spain
- Corresponding author. (K.-J.T.); (A.T.)
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22
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Shin HJ, Kim J, Kim S, Kim H, Nguyen VL, Lee YH, Lim SC, Son JH. Transient Carrier Cooling Enhanced by Grain Boundaries in Graphene Monolayer. ACS APPLIED MATERIALS & INTERFACES 2017; 9:41026-41033. [PMID: 29072440 DOI: 10.1021/acsami.7b12812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Using a high terahertz (THz) electric field (ETHz), the carrier scattering in graphene was studied with an electric field of up to 282 kV/cm. When the grain size of graphene monolayers varies from small (5 μm) and medium (70 μm) to large grains (500 μm), the dominant carrier scattering source in large- and small-grained graphene differs at high THz field, i.e., there is optical phonon scattering for large grains and defect scattering for small grains. Although the electron-optical phonon coupling strength is the same for all grain sizes in our study, the enhanced optical phonon scattering in the high THz field from the large-grained graphene is caused by a higher optical phonon temperature, originating from the slow relaxation of accelerated electrons. Unlike the large-grained graphene, lower electron and optical phonon temperatures are found in the small-grained graphene monolayer, resulting from the effective carrier cooling through the defects, called supercollisions. Our results indicate that the carrier mobility in the high-crystalline graphene is easily vulnerable to scattering by the optical phonons. Thus, controlling the population of defect sites, as a means for carrier cooling, can enhance the carrier mobility at high electric fields in graphene electronics by suppressing the heating of optical phonons.
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Affiliation(s)
- Hee Jun Shin
- Department of Physics, University of Seoul , Seoul 02504, Republic of Korea
- Research Group of Food Safety, Korea Food Research Institute , Wanju 55365, Republic of Korea
| | | | | | - Hyeongmun Kim
- Department of Physics, University of Seoul , Seoul 02504, Republic of Korea
| | | | | | | | - Joo-Hiuk Son
- Department of Physics, University of Seoul , Seoul 02504, Republic of Korea
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23
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Crassee I, Gallmann L, Gäumann G, Matthews M, Yanagisawa H, Feurer T, Hengsberger M, Keller U, Osterwalder J, Wörner HJ, Wolf JP. Strong field transient manipulation of electronic states and bands. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2017; 4:061505. [PMID: 29308417 PMCID: PMC5739908 DOI: 10.1063/1.4996424] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/18/2017] [Indexed: 06/07/2023]
Abstract
In the present review, laser fields are so strong that they become part of the electronic potential, and sometimes even dominate the Coulomb contribution. This manipulation of atomic potentials and of the associated states and bands finds fascinating applications in gases and solids, both in the bulk and at the surface. We present some recent spectacular examples obtained within the NCCR MUST in Switzerland.
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Affiliation(s)
- I Crassee
- Applied Physics, GAP, University of Geneva, 22 Ch. de Pinchat, 1211 Geneva 4, Switzerland
| | | | - G Gäumann
- Institute of Applied Physics, University of Bern, Sidlerstr 5, 3012 Bern, Switzerland
| | - M Matthews
- Applied Physics, GAP, University of Geneva, 22 Ch. de Pinchat, 1211 Geneva 4, Switzerland
| | - H Yanagisawa
- Department of Physics, University of Zurich, Winterthurerstr 190, 8057 Zurich, Switzerland
| | - T Feurer
- Institute of Applied Physics, University of Bern, Sidlerstr 5, 3012 Bern, Switzerland
| | - M Hengsberger
- Department of Physics, University of Zurich, Winterthurerstr 190, 8057 Zurich, Switzerland
| | - U Keller
- Department of Physics, Institute for Quantum Electronics, ETH-Zurich, 8093 Zurich, Switzerland
| | - J Osterwalder
- Department of Physics, University of Zurich, Winterthurerstr 190, 8057 Zurich, Switzerland
| | - H J Wörner
- Physical Chemistry Laboratory, ETHZ, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - J P Wolf
- Applied Physics, GAP, University of Geneva, 22 Ch. de Pinchat, 1211 Geneva 4, Switzerland
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24
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Constant TJ, Hornett SM, Chang DE, Hendry E. Intensity dependences of the nonlinear optical excitation of plasmons in graphene. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2017; 375:rsta.2016.0066. [PMID: 28219998 PMCID: PMC5321828 DOI: 10.1098/rsta.2016.0066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/31/2016] [Indexed: 06/06/2023]
Abstract
Recently, we demonstrated an all-optical coupling scheme for plasmons, which takes advantage of the intrinsic nonlinear optical response of graphene. Frequency mixing using free-space, visible light pulses generates surface plasmons in a planar graphene sample, where the phase matching condition can define both the wavevector and energy of surface waves and intraband transitions. Here, we also show that the plasmon generation process is strongly intensity-dependent, with resonance features washed out for absorbed pulse fluences greater than 0.1 J m-2 This implies a subtle interplay between the nonlinear generation process and sample heating. We discuss these effects in terms of a non-equilibrium charge distribution using a two-temperature model.This article is part of the themed issue 'New horizons for nanophotonics'.
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Affiliation(s)
- T J Constant
- Electromagnetic Materials Group, Department of Physics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, Devon EX4 4QL, UK
| | - S M Hornett
- Electromagnetic Materials Group, Department of Physics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, Devon EX4 4QL, UK
| | - D E Chang
- Institut de Ciències Fotòniques (ICFO), Mediterranean Technology Park, Castelldefels (Barcelona) 08860, Spain
| | - E Hendry
- Electromagnetic Materials Group, Department of Physics, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, Devon EX4 4QL, UK
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25
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Lu Y, Yang Y, Zhang T, Ge Z, Chang H, Xiao P, Xie Y, Hua L, Li Q, Li H, Ma B, Guan N, Ma Y, Chen Y. Photoprompted Hot Electrons from Bulk Cross-Linked Graphene Materials and Their Efficient Catalysis for Atmospheric Ammonia Synthesis. ACS NANO 2016; 10:10507-10515. [PMID: 27934092 DOI: 10.1021/acsnano.6b06472] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Ammonia synthesis is the single most important chemical process in industry and has used the successful heterogeneous Haber-Bosch catalyst for over 100 years and requires processing under both high temperature (300-500 °C) and pressure (200-300 atm); thus, it has huge energy costs accounting for about 1-3% of human's energy consumption. Therefore, there has been a long and vigorous exploration to find a milder alternative process. Here, we demonstrate that by using an iron- and graphene-based catalyst, Fe@3DGraphene, hot (ejected) electrons from this composite catalyst induced by visible light in a wide range of wavelength up to red could efficiently facilitate the activation of N2 and generate ammonia with H2 directly at ambient pressure using light (including simulated sun light) illumination directly. No external voltage or electrochemical or any other agent is needed. The production rate increases with increasing light frequency under the same power and with increasing power under the same frequency. The mechanism is confirmed by the detection of the intermediate N2H4 and also with a measured apparent activation energy only ∼1/4 of the iron based Haber-Bosch catalyst. Combined with the morphology control using alumina as the structural promoter, the catalyst retains its activity in a 50 h test.
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Affiliation(s)
- Yanhong Lu
- School of Chemistry & Material Science, Langfang Teachers University , Langfang 065000, China
| | | | | | | | | | | | - Yuanyuan Xie
- Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023, China
| | - Lei Hua
- Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023, China
| | - Qingyun Li
- Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023, China
| | - Haiyang Li
- Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023, China
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26
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Hornett SM, Stantchev RI, Vardaki MZ, Beckerleg C, Hendry E. Subwavelength Terahertz Imaging of Graphene Photoconductivity. NANO LETTERS 2016; 16:7019-7024. [PMID: 27736073 PMCID: PMC5115732 DOI: 10.1021/acs.nanolett.6b03168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 09/14/2016] [Indexed: 05/23/2023]
Abstract
Using a spatially structured, optical pump pulse with a terahertz (THz) probe pulse, we are able to determine spatial variations of the ultrafast THz photoconductivity with subwavelength resolution (75 μm ≈ λ/5 at 0.8 THz) in a planar graphene sample. We compare our results to Raman spectroscopy and correlate the existence of the spatial inhomogeneities between the two measurements. We find a strong correlation with inhomogeneity in electron density. This demonstrates the importance of eliminating inhomogeneities in doping density during CVD growth and fabrication for photoconductive devices.
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Affiliation(s)
- Samuel M. Hornett
- Physics Building, Stocker Road, University of Exeter, Exeter, Devon, United Kingdom, EX4 4QL
| | - Rayko I. Stantchev
- Physics Building, Stocker Road, University of Exeter, Exeter, Devon, United Kingdom, EX4 4QL
| | - Martha Z. Vardaki
- Physics Building, Stocker Road, University of Exeter, Exeter, Devon, United Kingdom, EX4 4QL
| | - Chris Beckerleg
- Physics Building, Stocker Road, University of Exeter, Exeter, Devon, United Kingdom, EX4 4QL
| | - Euan Hendry
- Physics Building, Stocker Road, University of Exeter, Exeter, Devon, United Kingdom, EX4 4QL
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27
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THz-circuits driven by photo-thermoelectric, gate-tunable graphene-junctions. Sci Rep 2016; 6:35654. [PMID: 27762291 PMCID: PMC5071831 DOI: 10.1038/srep35654] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 10/03/2016] [Indexed: 11/21/2022] Open
Abstract
For future on-chip communication schemes, it is essential to integrate nanoscale materials with an ultrafast optoelectronic functionality into high-frequency circuits. The atomically thin graphene has been widely demonstrated to be suitable for photovoltaic and optoelectronic devices because of its broadband optical absorption and its high electron mobility. Moreover, the ultrafast relaxation of photogenerated charge carriers has been verified in graphene. Here, we show that dual-gated graphene junctions can be functional parts of THz-circuits. As the underlying optoelectronic process, we exploit ultrafast photo-thermoelectric currents. We describe an immediate photo-thermoelectric current of the unbiased device following a femtosecond laser excitation. For a picosecond time-scale after the optical excitation, an additional photo-thermoelectric contribution shows up, which exhibits the fingerprint of a spatially inverted temperature profile. The latter can be understood by the different time-constants and thermal coupling mechanisms of the electron and phonon baths within graphene to the substrate and the metal contacts. The interplay of the processes gives rise to ultrafast electromagnetic transients in high-frequency circuits, and it is equally important for a fundamental understanding of graphene-based ultrafast photodetectors and switches.
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28
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König-Otto JC, Mittendorff M, Winzer T, Kadi F, Malic E, Knorr A, Berger C, de Heer WA, Pashkin A, Schneider H, Helm M, Winnerl S. Slow Noncollinear Coulomb Scattering in the Vicinity of the Dirac Point in Graphene. PHYSICAL REVIEW LETTERS 2016; 117:087401. [PMID: 27588881 DOI: 10.1103/physrevlett.117.087401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Indexed: 06/06/2023]
Abstract
The Coulomb scattering dynamics in graphene in energetic proximity to the Dirac point is investigated by polarization resolved pump-probe spectroscopy and microscopic theory. Collinear Coulomb scattering rapidly thermalizes the carrier distribution in k directions pointing radially away from the Dirac point. Our study reveals, however, that, in almost intrinsic graphene, full thermalization in all directions relying on noncollinear scattering is much slower. For low photon energies, carrier-optical-phonon processes are strongly suppressed and Coulomb mediated noncollinear scattering is remarkably slow, namely on a ps time scale. This effect is very promising for infrared and THz devices based on hot carrier effects.
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Affiliation(s)
- J C König-Otto
- Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden, Germany
- Technische Universität Dresden, 01062 Dresden, Germany
| | - M Mittendorff
- University of Maryland, College Park, Maryland 20742, USA
| | - T Winzer
- Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - F Kadi
- Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - E Malic
- Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - A Knorr
- Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - C Berger
- Georgia Institute of Technology, Atlanta, Georgia 30332, USA
- Institut Néel, CNRS-Université Alpes, 38042 Grenoble, France
| | - W A de Heer
- Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - A Pashkin
- Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden, Germany
| | - H Schneider
- Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden, Germany
| | - M Helm
- Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden, Germany
- Technische Universität Dresden, 01062 Dresden, Germany
| | - S Winnerl
- Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden, Germany
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29
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Nurlaela E, Wang H, Shinagawa T, Flanagan S, Ould-Chikh S, Qureshi M, Mics Z, Sautet P, Le Bahers T, Cánovas E, Bonn M, Takanabe K. Enhanced Kinetics of Hole Transfer and Electrocatalysis during Photocatalytic Oxygen Evolution by Cocatalyst Tuning. ACS Catal 2016. [DOI: 10.1021/acscatal.6b00508] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Ela Nurlaela
- Division
of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900, Saudi Arabia
| | - Hai Wang
- Department
of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Graduate
School of Material Science in Mainz, University of Mainz, Staudingerweg
9, 55128 Mainz, Germany
| | - Tatsuya Shinagawa
- Division
of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900, Saudi Arabia
| | - Sean Flanagan
- Division
of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900, Saudi Arabia
| | - Samy Ould-Chikh
- Division
of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900, Saudi Arabia
| | - Muhammad Qureshi
- Division
of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900, Saudi Arabia
| | - Zoltán Mics
- Department
of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Philippe Sautet
- Université de Lyon, Université Claude Bernard Lyon 1, ENS Lyon, Centre Nationale de Recherche Scientifique, 46 allée d’Italie, 69007 Lyon Cedex 07, France
| | - Tangui Le Bahers
- Université de Lyon, Université Claude Bernard Lyon 1, ENS Lyon, Centre Nationale de Recherche Scientifique, 46 allée d’Italie, 69007 Lyon Cedex 07, France
| | - Enrique Cánovas
- Department
of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Mischa Bonn
- Department
of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Kazuhiro Takanabe
- Division
of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900, Saudi Arabia
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30
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Alberding BG, Kushto GP, Lane PA, Heilweil EJ. Reduced Photoconductivity Observed by Time-Resolved Terahertz Spectroscopy in Metal Nanofilms with and without Adhesion Layers. APPLIED PHYSICS LETTERS 2016; 108. [PMID: 27818524 PMCID: PMC5094464 DOI: 10.1063/1.4953208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Non-contact, optical time-resolved terahertz spectroscopy (TRTS) has been used to study the transient photoconductivity of nanometer-scale metallic films deposited on fused quartz substrates. Samples of 8 nm thick gold or titanium show an instrument-limited (ca. 0.5 ps) decrease in conductivity following photoexcitation due to electron-phonon coupling and subsequent increased lattice temperatures which increases charge carrier scattering. In contrast, for samples of 8 nm gold with a 4 nm adhesion layer of titanium or chromium, a ca. 70 ps rise time for the lattice temperature increase is observed. These results establish the increased transient terahertz transmission sign change of metallic compared to semiconductor materials. The results also suggest nanoscale gold films that utilize an adhesion material do not consist of distinct layers.
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Affiliation(s)
- Brian G Alberding
- Radiation Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899, USA
| | - Gary P Kushto
- Optical Sciences Division, US Naval Research Laboratory, Washington, DC 20375, USA
| | - Paul A Lane
- Optical Sciences Division, US Naval Research Laboratory, Washington, DC 20375, USA
| | - Edwin J Heilweil
- Radiation Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899, USA
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31
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Microscopic origins of the terahertz carrier relaxation and cooling dynamics in graphene. Nat Commun 2016; 7:11617. [PMID: 27221060 PMCID: PMC4894949 DOI: 10.1038/ncomms11617] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/14/2016] [Indexed: 11/08/2022] Open
Abstract
The ultrafast dynamics of hot carriers in graphene are key to both understanding of fundamental carrier–carrier interactions and carrier–phonon relaxation processes in two-dimensional materials, and understanding of the physics underlying novel high-speed electronic and optoelectronic devices. Many recent experiments on hot carriers using terahertz spectroscopy and related techniques have interpreted the variety of observed signals within phenomenological frameworks, and sometimes invoke extrinsic effects such as disorder. Here, we present an integrated experimental and theoretical programme, using ultrafast time-resolved terahertz spectroscopy combined with microscopic modelling, to systematically investigate the hot-carrier dynamics in a wide array of graphene samples having varying amounts of disorder and with either high or low doping levels. The theory reproduces the observed dynamics quantitatively without the need to invoke any fitting parameters, phenomenological models or extrinsic effects such as disorder. We demonstrate that the dynamics are dominated by the combined effect of efficient carrier–carrier scattering, which maintains a thermalized carrier distribution, and carrier–optical–phonon scattering, which removes energy from the carrier liquid. Design of high-speed graphene-based devices relies on understanding of its ultrafast carrier dynamics. Here, the authors combine time-resolved terahertz spectroscopy and microscopic modelling to unveil the interplay between the scattering mechanisms dominating the ultrafast relaxation pathways in graphene.
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32
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Mics Z, Tielrooij KJ, Parvez K, Jensen SA, Ivanov I, Feng X, Müllen K, Bonn M, Turchinovich D. Thermodynamic picture of ultrafast charge transport in graphene. Nat Commun 2015; 6:7655. [PMID: 26179498 PMCID: PMC4518297 DOI: 10.1038/ncomms8655] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Accepted: 05/28/2015] [Indexed: 12/22/2022] Open
Abstract
The outstanding charge transport properties of graphene enable numerous electronic applications of this remarkable material, many of which are expected to operate at ultrahigh speeds. In the regime of ultrafast, sub-picosecond electric fields, however, the very high conduction properties of graphene are not necessarily preserved, with the physical picture explaining this behaviour remaining unclear. Here we show that in graphene, the charge transport on an ultrafast timescale is determined by a simple thermodynamic balance maintained within the graphene electronic system acting as a thermalized electron gas. The energy of ultrafast electric fields applied to graphene is converted into the thermal energy of its entire charge carrier population, near-instantaneously raising the electronic temperature. The dynamic interplay between heating and cooling of the electron gas ultimately defines the ultrafast conductivity of graphene, which in a highly nonlinear manner depends on the dynamics and the strength of the applied electric fields. A linear energy–momentum relation of graphene results in a high direct-current electron mobility, but this is not necessarily true at terahertz frequencies. Here, the authors show that its ultrafast conductivity is dependent on a highly nonlinear interplay between heating and cooling of the electron gas.
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Affiliation(s)
- Zoltán Mics
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Klaas-Jan Tielrooij
- 1] Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany [2] ICFO-Institut de Ciències Fotòniques, Mediterranean Technology Park, Castelldefels, Barcelona 08860, Spain
| | - Khaled Parvez
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Søren A Jensen
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Ivan Ivanov
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Xinliang Feng
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Klaus Müllen
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Dmitry Turchinovich
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
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33
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Tielrooij KJ, Piatkowski L, Massicotte M, Woessner A, Ma Q, Lee Y, Myhro KS, Lau CN, Jarillo-Herrero P, van Hulst NF, Koppens FHL. Generation of photovoltage in graphene on a femtosecond timescale through efficient carrier heating. NATURE NANOTECHNOLOGY 2015; 10:437-43. [PMID: 25867941 DOI: 10.1038/nnano.2015.54] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 02/23/2015] [Indexed: 05/13/2023]
Abstract
Graphene is a promising material for ultrafast and broadband photodetection. Earlier studies have addressed the general operation of graphene-based photothermoelectric devices and the switching speed, which is limited by the charge carrier cooling time, on the order of picoseconds. However, the generation of the photovoltage could occur at a much faster timescale, as it is associated with the carrier heating time. Here, we measure the photovoltage generation time and find it to be faster than 50 fs. As a proof-of-principle application of this ultrafast photodetector, we use graphene to directly measure, electrically, the pulse duration of a sub-50 fs laser pulse. The observation that carrier heating is ultrafast suggests that energy from absorbed photons can be efficiently transferred to carrier heat. To study this, we examine the spectral response and find a constant spectral responsivity of between 500 and 1,500 nm. This is consistent with efficient electron heating. These results are promising for ultrafast femtosecond and broadband photodetector applications.
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Affiliation(s)
- K J Tielrooij
- ICFO - Institut de Ciències Fotòniques, Mediterranean Technology Park, Castelldefels (Barcelona) 08860, Spain
| | - L Piatkowski
- ICFO - Institut de Ciències Fotòniques, Mediterranean Technology Park, Castelldefels (Barcelona) 08860, Spain
| | - M Massicotte
- ICFO - Institut de Ciències Fotòniques, Mediterranean Technology Park, Castelldefels (Barcelona) 08860, Spain
| | - A Woessner
- ICFO - Institut de Ciències Fotòniques, Mediterranean Technology Park, Castelldefels (Barcelona) 08860, Spain
| | - Q Ma
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Y Lee
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - K S Myhro
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - C N Lau
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - P Jarillo-Herrero
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - N F van Hulst
- 1] ICFO - Institut de Ciències Fotòniques, Mediterranean Technology Park, Castelldefels (Barcelona) 08860, Spain [2] ICREA - Institució Catalana de Recerca i Estudis Avançats, Barcelona 08010, Spain
| | - F H L Koppens
- ICFO - Institut de Ciències Fotòniques, Mediterranean Technology Park, Castelldefels (Barcelona) 08860, Spain
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34
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Tielrooij KJ, Massicotte M, Piatkowski L, Woessner A, Ma Q, Jarillo-Herrero P, van Hulst NF, Koppens FHL. Hot-carrier photocurrent effects at graphene-metal interfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:164207. [PMID: 25835338 DOI: 10.1088/0953-8984/27/16/164207] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Photoexcitation of graphene leads to an interesting sequence of phenomena, some of which can be exploited in optoelectronic devices based on graphene. In particular, the efficient and ultrafast generation of an electron distribution with an elevated electron temperature and the concomitant generation of a photo-thermoelectric voltage at symmetry-breaking interfaces is of interest for photosensing and light harvesting. Here, we experimentally study the generated photocurrent at the graphene-metal interface, focusing on the time-resolved photocurrent, the effects of photon energy, Fermi energy and light polarization. We show that a single framework based on photo-thermoelectric photocurrent generation explains all experimental results.
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Affiliation(s)
- K J Tielrooij
- ICFO-Institut de Ciéncies Fotóniques, Mediterranean Technology Park, Castelldefels (Barcelona) 08860, Spain
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35
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Johannsen JC, Ulstrup S, Crepaldi A, Cilento F, Zacchigna M, Miwa JA, Cacho C, Chapman RT, Springate E, Fromm F, Raidel C, Seyller T, King PDC, Parmigiani F, Grioni M, Hofmann P. Tunable carrier multiplication and cooling in graphene. NANO LETTERS 2015; 15:326-331. [PMID: 25458168 DOI: 10.1021/nl503614v] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Time- and angle-resolved photoemission measurements on two doped graphene samples displaying different doping levels reveal remarkable differences in the ultrafast dynamics of the hot carriers in the Dirac cone. In the more strongly (n-)doped graphene, we observe larger carrier multiplication factors (>3) and a significantly faster phonon-mediated cooling of the carriers back to equilibrium compared to in the less (p-)doped graphene. These results suggest that a careful tuning of the doping level allows for an effective manipulation of graphene's dynamical response to a photoexcitation.
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Affiliation(s)
- Jens Christian Johannsen
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL) , 1015 Lausanne, Switzerland
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