1
|
Chen J, Bao W, Wang Z, Xu K, Tang D. Nonequilibrium electron-phonon coupling across the interfaces between Al nanofilm and GaN. Phys Chem Chem Phys 2024; 26:8504-8514. [PMID: 38411463 DOI: 10.1039/d3cp06054c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
The metal Al is commonly attached to external circuits as the source and drain in GaN-based field effect transistors, so profound comprehension of the energy transfer between electrons and phonons in Al/GaN is crucial for nanofabrication and thermal management of electronic devices. Time-domain thermoreflectance (TDTR) is an effective technique for measuring the strength of non-equilibrium electron-phonon (e-ph) coupling. The two-temperature model (TTM) is widely employed in conjunction with TDTR methods to determine e-ph coupling factors. However, TTM is a gray method and cannot take into account interactions between electrons and different phonon modes. Therefore, in this work, we use the TDTR technique to analyze the non-equilibrium transport properties of pure Al and the thickness dependence of the e-ph coupling with Al nanofilms, and the coupling strengths of high-energy electrons excited by femtosecond lasers with different modes of phonons are obtained in conjunction with MTM. The results show that the e-ph coupling coefficients of Al nanofilms on GaN substrates are larger than those of pure Al. In conjunction with the TTM, we determined the coupling strength between high-energy electrons excited by femtosecond laser pulses and various phonon modes. Compared to the transverse acoustic branch-1 (TA1) and transverse acoustic branch-2 (TA2) modes, the longitudinal acoustic (LA) phonon mode of Al exhibits a higher e-ph coupling factor. This suggests that the LA mode predominates in the electron relaxation process after ultrafast femtosecond laser excitation. This study provides experimental and theoretical guidance for laser processing and electronic device design.
Collapse
Affiliation(s)
- Jiao Chen
- Thermal Engineering and Power Department, China University of Petroleum, Qingdao 266580, China.
| | - Wenlong Bao
- Qingdao Cigarette Factory, China Tobacco Shandong Industrial Co., Ltd, Qingdao 266100, Shandong, China
| | - Zhaoliang Wang
- Thermal Engineering and Power Department, China University of Petroleum, Qingdao 266580, China.
| | - Ke Xu
- Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, China
| | - Dawei Tang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China
| |
Collapse
|
2
|
Meng Y, Gong A, Chen Z, Wang Q, Guo J, Li Z, Li J. Atomistic-Continuum Study of an Ultrafast Melting Process Controlled by a Femtosecond Laser-Pulse Train. Materials (Basel) 2023; 17:185. [PMID: 38204038 PMCID: PMC10779960 DOI: 10.3390/ma17010185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/18/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024]
Abstract
In femtosecond laser fabrication, the laser-pulse train shows great promise in improving processing efficiency, quality, and precision. This research investigates the influence of pulse number, pulse interval, and pulse energy ratio on the lateral and longitudinal ultrafast melting process using an experiment and the molecular dynamics coupling two-temperature model (MD-TTM model), which incorporates temperature-dependent thermophysical parameters. The comparison of experimental and simulation results under single and double pulses proves the reliability of the MD-TTM model and indicates that as the pulse number increases, the melting threshold at the edge region of the laser spot decreases, resulting in a larger diameter of the melting region in the 2D lateral melting results. Using the same model, the lateral melting results of five pulses are simulated. Moreover, the longitudinal melting results are also predicted, and an increasing pulse number leads to a greater early-stage melting depth in the melting process. In the case of double femtosecond laser pulses, the pulse interval and pulse energy ratio also affect the early-stage melting depth, with the best enhancement observed with a 2 ps interval and a 3:7 energy ratio. However, pulse number, pulse energy ratio, and pulse interval do not affect the final melting depth with the same total energies. The findings mean that the phenomena of melting region can be flexibly manipulated through the laser-pulse train, which is expected to be applied to improve the structural precision and boundary quality.
Collapse
Affiliation(s)
- Yu Meng
- Laser Micro/Nano Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
- Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing 314019, China
| | - An Gong
- Laser Micro/Nano Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Zhicheng Chen
- Laser Micro/Nano Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Qingsong Wang
- Laser Micro/Nano Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Jianwu Guo
- Laser Micro/Nano Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
- Yangtze Delta Region Academy of Beijing Institute of Technology, Jiaxing 314019, China
| | - Zihao Li
- Laser Micro/Nano Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Jiafang Li
- School of Physics, Beijing Institute of Technology, Beijing 100081, China
| |
Collapse
|
3
|
Choi IH, Jeong SG, Min T, Lee J, Choi WS, Lee JS. Giant Enhancement of Electron-Phonon Coupling in Dimensionality-Controlled SrRuO 3 Heterostructures. Adv Sci (Weinh) 2023; 10:e2300012. [PMID: 37052542 DOI: 10.1002/advs.202300012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 02/23/2023] [Indexed: 06/04/2023]
Abstract
Electrons in crystals interact closely with quantized lattice degree of freedom, determining fundamental electrodynamic behaviors and versatile correlated functionalities. However, the strength of the electron-phonon interaction is so far determined as an intrinsic value of a given material, restricting the development of potential electronic and phononic applications employing the tunable coupling strength. Here, it is demonstrated that the electron-phonon coupling in SrRuO3 can be largely controlled by multiple intuitive tuning knobs available in synthetic crystals. The coupling strength of quasi-2D SrRuO3 is enhanced by ≈300-fold compared with that of bulk SrRuO3 . This enormous enhancement is attributed to the non-local nature of the electron-phonon coupling within the well-defined synthetic atomic network, which becomes dominant in the limit of the 2D electronic state. These results provide valuable opportunities for engineering the electron-phonon coupling, leading to a deeper understanding of the strongly coupled charge and lattice dynamics in quantum materials.
Collapse
Affiliation(s)
- In Hyeok Choi
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea
| | - Seung Gyo Jeong
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Taewon Min
- Department of Physics, Pusan National University, Busan, 46241, Republic of Korea
| | - Jaekwang Lee
- Department of Physics, Pusan National University, Busan, 46241, Republic of Korea
| | - Woo Seok Choi
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jong Seok Lee
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea
| |
Collapse
|
4
|
Durham DB, Ophus C, Siddiqui KM, Minor AM, Filippetto D. Accurate quantification of lattice temperature dynamics from ultrafast electron diffraction of single-crystal films using dynamical scattering simulations. Struct Dyn 2022; 9:064302. [PMID: 36484070 PMCID: PMC9726223 DOI: 10.1063/4.0000170] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 11/14/2022] [Indexed: 06/17/2023]
Abstract
In ultrafast electron diffraction (UED) experiments, accurate retrieval of time-resolved structural parameters, such as atomic coordinates and thermal displacement parameters, requires an accurate scattering model. Unfortunately, kinematical models are often inaccurate even for relativistic electron probes, especially for dense, oriented single crystals where strong channeling and multiple scattering effects are present. This article introduces and demonstrates dynamical scattering models tailored for quantitative analysis of UED experiments performed on single-crystal films. As a case study, we examine ultrafast laser heating of single-crystal gold films. Comparison of kinematical and dynamical models reveals the strong effects of dynamical scattering within nm-scale films and their dependence on sample topography and probe kinetic energy. Applying to UED experiments on an 11 nm thick film using 750 keV electron probe pulses, the dynamical models provide a tenfold improvement over a comparable kinematical model in matching the measured UED patterns. Also, the retrieved lattice temperature rise is in very good agreement with predictions based on previously measured optical constants of gold, whereas fitting the Debye-Waller factor retrieves values that are more than three times lower. Altogether, these results show the importance of a dynamical scattering theory for quantitative analysis of UED and demonstrate models that can be practically applied to single-crystal materials and heterostructures.
Collapse
Affiliation(s)
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Khalid M. Siddiqui
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | | | - Daniele Filippetto
- Accelerator Technology and Applied Physics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| |
Collapse
|
5
|
Arefev MI, Shugaev MV, Zhigilei LV. Kinetics of laser-induced melting of thin gold film: How slow can it get? Sci Adv 2022; 8:eabo2621. [PMID: 36129986 PMCID: PMC9491712 DOI: 10.1126/sciadv.abo2621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 08/04/2022] [Indexed: 06/15/2023]
Abstract
Melting is a common and well-studied phenomenon that still reveals new facets when triggered by laser excitation and probed with ultrafast electron diffraction. Recent experimental evidence of anomalously slow nanosecond-scale melting of thin gold films irradiated by femtosecond laser pulses motivates computational efforts aimed at revealing the underlying mechanisms of melting. Atomistic simulations reveal that a combined effect of lattice superheating and relaxation of laser-induced stresses ensures the dominance of the homogeneous melting mechanism at all energies down to the melting threshold and keeps the time scale of melting within ~100 picoseconds. The much longer melting times and the prominent contribution of heterogeneous melting inferred from the experiments cannot be reconciled with the atomistic simulations by any reasonable variation of the electron-phonon coupling strength, thus suggesting the need for further coordinated experimental and theoretical efforts aimed at addressing the mechanisms and kinetics of laser-induced melting in the vicinity of melting threshold.
Collapse
|
6
|
Akhmetov F, Medvedev N, Makhotkin I, Ackermann M, Milov I. Effect of Atomic-Temperature Dependence of the Electron-Phonon Coupling in Two-Temperature Model. Materials (Basel) 2022; 15:5193. [PMID: 35897625 DOI: 10.3390/ma15155193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/14/2022] [Accepted: 07/17/2022] [Indexed: 11/16/2022]
Abstract
Ultrafast laser irradiation of metals can often be described theoretically with the two-temperature model. The energy exchange between the excited electronic system and the atomic one is governed by the electron–phonon coupling parameter. The electron–phonon coupling depends on both, the electronic and the atomic temperature. We analyze the effect of the dependence of the electron–phonon coupling parameter on the atomic temperature in ruthenium, gold, and palladium. It is shown that the dependence on the atomic temperature induces nonlinear behavior, in which a higher initial electronic temperature leads to faster electron–phonon equilibration. Analysis of the experimental measurements of the transient thermoreflectance of the laser-irradiated ruthenium thin film allows us to draw some, albeit indirect, conclusions about the limits of the applicability of the different coupling parametrizations.
Collapse
|
7
|
Kang K, Choi GM. Electron-Phonon Coupling Parameter of Ferromagnetic Metal Fe and Co. Materials (Basel) 2021; 14:2755. [PMID: 34071011 PMCID: PMC8197080 DOI: 10.3390/ma14112755] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/19/2021] [Accepted: 05/21/2021] [Indexed: 11/22/2022]
Abstract
The electron-phonon coupling (g) parameter plays a critical role in the ultrafast transport of heat, charge, and spin in metallic materials. However, the exact determination of the g parameter is challenging because of the complicated process during the non-equilibrium state. In this study, we investigate the g parameters of ferromagnetic 3d transition metal (FM) layers, Fe and Co, using time-domain thermoreflectance. We measure a transient increase in temperature of Au in an FM/Au bilayer; the Au layer efficiently detects the strong heat flow during the non-equilibrium between electrons and phonons in FM. The g parameter of the FM is determined by analyzing the temperature dynamics using thermal circuit modeling. The determined g values are 8.8-9.4 × 1017 W m-3 K-1 for Fe and 9.6-12.2 × 1017 W m-3 K-1 for Co. Our results demonstrate that all 3d transition FMs have a similar g value, in the order of 1018 W m-3 K-1.
Collapse
Affiliation(s)
- Kyuhwe Kang
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Korea;
| | - Gyung-Min Choi
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Korea;
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon 16419, Korea
| |
Collapse
|
8
|
Gorobtsov OY, Ponet L, Patel SKK, Hua N, Shabalin AG, Hrkac S, Wingert J, Cela D, Glownia JM, Zhu D, Medapalli R, Chollet M, Fullerton EE, Artyukhin S, Shpyrko OG, Singer A. Femtosecond control of phonon dynamics near a magnetic order critical point. Nat Commun 2021; 12:2865. [PMID: 34001880 DOI: 10.1038/s41467-021-23059-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 04/13/2021] [Indexed: 11/21/2022] Open
Abstract
The spin-phonon interaction in spin density wave (SDW) systems often determines the free energy landscape that drives the evolution of the system. When a passing energy flux, such as photoexcitation, drives a crystalline system far from equilibrium, the resulting lattice displacement generates transient vibrational states. Manipulating intermediate vibrational states in the vicinity of the critical point, where the SDW order parameter changes dramatically, would then allow dynamical control over functional properties. Here we combine double photoexcitation with an X-ray free-electron laser (XFEL) probe to control and detect the lifetime and magnitude of the intermediate vibrational state near the critical point of the SDW in chromium. We apply Landau theory to identify the mechanism of control as a repeated partial quench and sub picosecond recovery of the SDW. Our results showcase the capabilities to influence and monitor quantum states by combining multiple optical photoexcitations with an XFEL probe. They open new avenues for manipulating and researching the behaviour of photoexcited states in charge and spin order systems near the critical point. Precise control of vibrational states coupled to electronic degrees of freedom could enable control over charge or magnetic order in a material. Here, the authors use a double-pulse photoexcitation combined with an X-ray probe to control vibrational states near the critical point of spin density wave in Cr films.
Collapse
|
9
|
Winter J, Spellauge M, Hermann J, Eulenkamp C, Huber HP, Schmidt M. Ultrashort single-pulse laser ablation of stainless steel, aluminium, copper and its dependence on the pulse duration. Opt Express 2021; 29:14561-14581. [PMID: 33985177 DOI: 10.1364/oe.421097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
In this work, we investigate single-pulse laser ablation of bulk stainless steel (AISI304), aluminium (Al) and copper (Cu) and its dependence on the pulse duration. We measured the reflectivity, ablation thresholds and volumes under the variation of pulse duration and fluence. The known drop of efficiency with increasing pulse duration is confirmed for single-pulse ablation in all three metals. We attribute the efficiency drop to a weakened photomechanically driven ablation process and a stronger contribution of photothermal phase explosion. The highest energetic efficiency and precision is achieved for pulse durations below the mechanical expansion time of 3-5 ps, where the stress confinement condition is fulfilled.
Collapse
|
10
|
Rajput M, Srinivasan R. Study of transmutation, gas production, and displacement damage in chromium for fusion neutron spectrum. ANN NUCL ENERGY 2020. [DOI: 10.1016/j.anucene.2019.107187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
11
|
Su MN, Ciccarino CJ, Kumar S, Dongare PD, Hosseini Jebeli SA, Renard D, Zhang Y, Ostovar B, Chang WS, Nordlander P, Halas NJ, Sundararaman R, Narang P, Link S. Ultrafast Electron Dynamics in Single Aluminum Nanostructures. Nano Lett 2019; 19:3091-3097. [PMID: 30935208 DOI: 10.1021/acs.nanolett.9b00503] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Aluminum nanostructures are a promising alternative material to noble metal nanostructures for several photonic and catalytic applications, but their ultrafast electron dynamics remain elusive. Here, we combine single-particle transient extinction spectroscopy and parameter-free first-principles calculations to investigate the non-equilibrium carrier dynamics in aluminum nanostructures. Unlike gold nanostructures, we find the sub-picosecond optical response of lithographically fabricated aluminum nanodisks to be more sensitive to the lattice temperature than the electron temperature. We assign the rise in the transient transmission to electron-phonon coupling with a pump-power-independent lifetime of 500 ± 100 fs and theoretically confirm this strong electron-phonon coupling behavior. We also measure electron-phonon lifetimes in chemically synthesized aluminum nanocrystals and find them to be even longer (1.0 ± 0.1 ps) than for the nanodisks. We also observe a rise and decay in the transient transmissions with amplitudes that scale with the surface-to-volume ratio of the aluminum nanodisks, implying a possible hot carrier trapping and detrapping at the native oxide shell-metal core interface.
Collapse
Affiliation(s)
| | | | - Sushant Kumar
- Department of Materials Science and Engineering , Rensselaer Polytechnic Institute , Troy , New York 12180 , United States
| | | | | | | | | | | | | | | | | | - Ravishankar Sundararaman
- Department of Materials Science and Engineering , Rensselaer Polytechnic Institute , Troy , New York 12180 , United States
| | | | | |
Collapse
|
12
|
VandenBussche EJ, Flannigan DJ. Sources of error in Debye-Waller-effect measurements relevant to studies of photoinduced structural dynamics. Ultramicroscopy 2018; 196:111-120. [PMID: 30352384 DOI: 10.1016/j.ultramic.2018.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 09/23/2018] [Accepted: 10/04/2018] [Indexed: 10/28/2022]
Abstract
We identify and quantify several practical effects likely to be present in both static and ultrafast electron-scattering experiments that may interfere with the Debye-Waller (DW) effect. Using 120-nm thick, small-grained, polycrystalline aluminum foils as a test system, we illustrate the impact of specimen tilting, in-plane translation, and changes in z height on Debye-Scherrer-ring intensities. We find that tilting by less than one degree can result in statistically-significant changes in diffracted-beam intensities for large specimen regions containing > 105 nanocrystalline grains. We demonstrate that, in addition to effective changes in the field of view with tilting, slight texturing of the film can result in deviations from expected DW-effect behavior. Further, we find that in-plane translations of as little as 20 nm also produce statistically-significant intensity changes, while normalization to total image counts eliminates such effects arising from changes in z height. The results indicate that the use of polycrystalline films in ultrafast electron-scattering experiments can greatly reduce the negative impacts of these effects as compared to single-crystal specimens, though it does not entirely eliminate them. Thus, it is important to account for such effects when studying thin-foil specimens having relatively short reciprocal-lattice rods.
Collapse
Affiliation(s)
- Elisah J VandenBussche
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, MN 55455, United States
| | - David J Flannigan
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE, Minneapolis, MN 55455, United States.
| |
Collapse
|
13
|
Edward S, Antoncecchi A, Zhang H, Sielcken H, Witte S, Planken PCM. Detection of periodic structures through opaque metal layers by optical measurements of ultrafast electron dynamics. Opt Express 2018; 26:23380-23396. [PMID: 30184840 DOI: 10.1364/oe.26.023380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 07/30/2018] [Indexed: 06/08/2023]
Abstract
We report on femtosecond optical pump-probe measurements of ultrafast electron dynamics to detect the presence of gratings buried underneath optically opaque gold layers. Electron energy diffusion and cooling are found to be strongly affected by the presence and type of metal buried below the gold layer. As a result, the spatially periodic buried grating is encoded on the electron temperature near the top surface, leading to a spatially periodic modulation of the optical properties near the gold surface from which a delayed probe pulse can be diffracted. Our measurements show that these effects may be useful for optical detection and alignment applications in semiconductor device manufacturing.
Collapse
|
14
|
Park W, Kodama T, Park J, Cho J, Sood A, Barako MT, Asheghi M, Goodson KE. Thermal Conduction across Metal-Dielectric Sidewall Interfaces. ACS Appl Mater Interfaces 2017; 9:30100-30106. [PMID: 28786284 DOI: 10.1021/acsami.7b06567] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The heat flow at the interfaces of complex nanostructures is three-dimensional in part due to the nonplanarity of interfaces. One example common in nanosystems is the situation when a significant fraction of the interfacial area is composed of sidewalls that are perpendicular to the principal plane, for example, in metallization structures for complementary metal-oxide semiconductor transistors. It is often observed that such sidewall interfaces contain significantly higher levels of microstructural disorder, which impedes energy carrier transport and leads to effective increases in interfacial resistance. The impact of these sidewall interfaces needs to be explored in greater depth for practical device engineering, and a related problem is that appropriate characterization techniques are not available. Here, we develop a novel electrothermal method and an intricate microfabricated structure to extract the thermal resistance of a sidewall interface between aluminum and silicon dioxide using suspended nanograting structures. The thermal resistance of the sidewall interface is measured to be ∼16 ± 5 m2 K GW-1, which is twice as large as the equivalent horizontal planar interface comprising the same materials in the experimental sample. The rough sidewall interfaces are observed using transmission electron micrographs, which may be more extensive than at interfaces in the substrate plan in the same nanostructure. A model based on a two-dimensional sinusoidal surface estimates the impact of the roughness on thermal resistance to be ∼2 m2 K GW-1. The large disparity between the model predictions and the experiments is attributed to the incomplete contact at the Al-SiO2 sidewall interfaces, inferred by observation of underetching of the silicon substrate below the sidewall opening. This study suggests that sidewall interfaces must be considered separately from planar interfaces in thermal analysis for nanostructured systems.
Collapse
Affiliation(s)
| | - Takashi Kodama
- Department of Mechanical Engineering, University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | | | - Jungwan Cho
- Department of Mechanical Engineering, Kyung Hee University , 1732 Deogyoung-daero, Giheung-gu, Yongin-si, Gyeounggi-do 446-701, South Korea
| | | | - Michael T Barako
- NG Next, Northrop Grumman Aerospace Systems , Redondo Beach, California 90278, United States
| | | | | |
Collapse
|
15
|
|
16
|
Sokolowski-Tinten K, Shen X, Zheng Q, Chase T, Coffee R, Jerman M, Li RK, Ligges M, Makasyuk I, Mo M, Reid AH, Rethfeld B, Vecchione T, Weathersby SP, Dürr HA, Wang XJ. Electron-lattice energy relaxation in laser-excited thin-film Au-insulator heterostructures studied by ultrafast MeV electron diffraction. Struct Dyn 2017; 4:054501. [PMID: 28795080 PMCID: PMC5522339 DOI: 10.1063/1.4995258] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 07/10/2017] [Indexed: 05/19/2023]
Abstract
We apply time-resolved MeV electron diffraction to study the electron-lattice energy relaxation in thin film Au-insulator heterostructures. Through precise measurements of the transient Debye-Waller-factor, the mean-square atomic displacement is directly determined, which allows to quantitatively follow the temporal evolution of the lattice temperature after short pulse laser excitation. Data obtained over an extended range of laser fluences reveal an increased relaxation rate when the film thickness is reduced or the Au-film is capped with an additional insulator top-layer. This behavior is attributed to a cross-interfacial coupling of excited electrons in the Au film to phonons in the adjacent insulator layer(s). Analysis of the data using the two-temperature-model taking explicitly into account the additional energy loss at the interface(s) allows to deduce the relative strength of the two relaxation channels.
Collapse
Affiliation(s)
- K Sokolowski-Tinten
- Faculty of Physics and Centre for Nanointegration Duisburg-Essen, University of Duisburg-Essen, Lotharstrasse 1, 47048 Duisburg, Germany
| | - X Shen
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| | - Q Zheng
- School of Materials and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, China
| | - T Chase
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| | - R Coffee
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| | - M Jerman
- Faculty of Physics and Centre for Nanointegration Duisburg-Essen, University of Duisburg-Essen, Lotharstrasse 1, 47048 Duisburg, Germany
| | - R K Li
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| | - M Ligges
- Faculty of Physics and Centre for Nanointegration Duisburg-Essen, University of Duisburg-Essen, Lotharstrasse 1, 47048 Duisburg, Germany
| | - I Makasyuk
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| | - M Mo
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| | - A H Reid
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| | - B Rethfeld
- Department of Physics and OPTIMAS Research Center, Technical University Kaiserslautern, Erwin-Schrödinger-Strae 46, 67663 Kaiserslautern, Germany
| | - T Vecchione
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| | - S P Weathersby
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| | - H A Dürr
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| | - X J Wang
- SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025, USA
| |
Collapse
|
17
|
Ma T, Liu Z, Wen J, Gao Y, Ren X, Chen H, Jin C, Ma XL, Xu N, Cheng HM, Ren W. Tailoring the thermal and electrical transport properties of graphene films by grain size engineering. Nat Commun 2017; 8:14486. [PMID: 28205514 DOI: 10.1038/ncomms14486] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 01/05/2017] [Indexed: 12/24/2022] Open
Abstract
Understanding the influence of grain boundaries (GBs) on the electrical and thermal transport properties of graphene films is essentially important for electronic, optoelectronic and thermoelectric applications. Here we report a segregation-adsorption chemical vapour deposition method to grow well-stitched high-quality monolayer graphene films with a tunable uniform grain size from ∼200 nm to ∼1 μm, by using a Pt substrate with medium carbon solubility, which enables the determination of the scaling laws of thermal and electrical conductivities as a function of grain size. We found that the thermal conductivity of graphene films dramatically decreases with decreasing grain size by a small thermal boundary conductance of ∼3.8 × 109 W m-2 K-1, while the electrical conductivity slowly decreases with an extraordinarily small GB transport gap of ∼0.01 eV and resistivity of ∼0.3 kΩ μm. Moreover, the changes in both the thermal and electrical conductivities with grain size change are greater than those of typical semiconducting thermoelectric materials.
Collapse
|
18
|
Ziaja B, Medvedev N, Tkachenko V, Maltezopoulos T, Wurth W. Time-resolved observation of band-gap shrinking and electron-lattice thermalization within X-ray excited gallium arsenide. Sci Rep 2015; 5:18068. [PMID: 26655671 DOI: 10.1038/srep18068] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 09/28/2015] [Indexed: 12/19/2022] Open
Abstract
Femtosecond X-ray irradiation of solids excites energetic photoelectrons that thermalize on a timescale of a few hundred femtoseconds. The thermalized electrons exchange energy with the lattice and heat it up. Experiments with X-ray free-electron lasers have unveiled so far the details of the electronic thermalization. In this work we show that the data on transient optical reflectivity measured in GaAs irradiated with femtosecond X-ray pulses can be used to follow electron-lattice relaxation up to a few tens of picoseconds. With a dedicated theoretical framework, we explain the so far unexplained reflectivity overshooting as a result of band-gap shrinking. We also obtain predictions for a timescale of electron-lattice thermalization, initiated by conduction band electrons in the temperature regime of a few eVs. The conduction and valence band carriers were then strongly non-isothermal. The presented scheme is of general applicability and can stimulate further studies of relaxation within X-ray excited narrow band-gap semiconductors.
Collapse
|
19
|
Lin KH, Strachan A. Role of direct electron-phonon coupling across metal-semiconductor interfaces in thermal transport via molecular dynamics. J Chem Phys 2015. [PMID: 26203038 DOI: 10.1063/1.4922893] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Keng-Hua Lin
- School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Alejandro Strachan
- School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| |
Collapse
|
20
|
Ochedowski O, Osmani O, Schade M, Bussmann BK, Ban-d’Etat B, Lebius H, Schleberger M. Graphitic nanostripes in silicon carbide surfaces created by swift heavy ion irradiation. Nat Commun 2014; 5:3913. [PMID: 24905053 DOI: 10.1038/ncomms4913] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Accepted: 04/07/2014] [Indexed: 11/09/2022] Open
|
21
|
Tomoda M, Dehoux T, Iwasaki Y, Matsuda O, Gusev VE, Wright OB. Nanoscale mechanical contacts mapped by ultrashort time-scale electron transport. Sci Rep 2014; 4:4790. [PMID: 24763385 DOI: 10.1038/srep04790] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 03/21/2014] [Indexed: 11/08/2022] Open
Abstract
Mechanical contacts are crucial to systems in engineering, electronics and biology. The microscopic nature of the contacting surfaces determines how they mesh on the nanoscale. There is thus much interest in methods that can map the actual area of two surfaces in contact--the real contact area--during the loading or unloading phases. We address this problem using an ultrafast optical technique to generate non-equilibrium electrons that diffuse across a nanoscale mechanical contact between two thin gold films deposited on sapphire. We image this process in the contact and near-contact regions to micron resolution in situ using transient optical reflectivity changes on femtosecond time scales. By use of a model of the ultrashort-time electron dynamics, we account for an up to ~40% drop in the transient optical reflectivity change on contact. We thereby show how the real contact area of a nanoscale contact can be mapped. Applications include the probing of microelectronic mechanical devices.
Collapse
|
22
|
Leguay PM, Lévy A, Chimier B, Deneuville F, Descamps D, Fourment C, Goyon C, Hulin S, Petit S, Peyrusse O, Santos JJ, Combis P, Holst B, Recoules V, Renaudin P, Videau L, Dorchies F. Ultrafast short-range disordering of femtosecond-laser-heated warm dense aluminum. Phys Rev Lett 2013; 111:245004. [PMID: 24483671 DOI: 10.1103/physrevlett.111.245004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Indexed: 06/03/2023]
Abstract
We have probed, with time-resolved x-ray absorption near-edge spectroscopy (XANES), a femtosecond-laser-heated aluminum foil with fluences up to 1 J/cm2. The spectra reveal a loss of the short-range order in a few picoseconds. This time scale is compared with the electron-ion equilibration time, calculated with a two-temperature model. Hydrodynamic simulations shed light on complex features that affect the foil dynamics, including progressive density change from solid to liquid (∼10 ps). In this density range, quantum molecular dynamics simulations indicate that XANES is a relevant probe of the ionic temperature.
Collapse
Affiliation(s)
- P M Leguay
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - A Lévy
- Ecole Polytechnique, LULI (Laboratoire d'Utilisation des Lasers Intenses), UMR 7605, F-91128 Palaiseau, France
| | - B Chimier
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - F Deneuville
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - D Descamps
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - C Fourment
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - C Goyon
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - S Hulin
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - S Petit
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - O Peyrusse
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - J J Santos
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| | - P Combis
- CEA-DAM-DIF, F-91297 Arpajon, France
| | - B Holst
- CEA-DAM-DIF, F-91297 Arpajon, France
| | | | | | - L Videau
- CEA-DAM-DIF, F-91297 Arpajon, France
| | - F Dorchies
- Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France
| |
Collapse
|
23
|
Abstract
After a decade's efforts, a large amount of highly luminescent metal nanoparticles with different sizes and surface chemistries have been developed. While the luminescence is often attributed to particle size effects, other structural parameters such as surface ligands, valence states of metal atoms and crystallinity of nanoparticles also have a significant influence on emission properties and mechanisms. In this review, we summarized the strategies used to create luminescent gold nanoparticles with sizes from few to millions of atoms and discussed how these structural factors affect their photoluminescence.
Collapse
Affiliation(s)
- Jie Zheng
- Department of Chemistry, University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX 75080, USA.
| | | | | | | |
Collapse
|
24
|
Abstract
We report a structure-property relationship in gold nanoparticles (NPs), grain-size effects, which not only allow material properties observed on different characteristic length scales to be engineered in a single NP but further enhance those properties due to the coupling among different-size grains. The grain size effects were achieved by creating polycrystalline gold NPs (pAuNPs) with two distinct grain-size populations (5 and 1 nm) comparable to electron mean free path and electron Fermi wavelength (EFW), respectively. Successful integration of molecular and plasmonic properties into a single nanostructure without additional fluorophores enables these highly polycrystalline AuNPs to serve as multimodal probes in a variety of optical microscopic imaging techniques.
Collapse
Affiliation(s)
| | | | | | - Jie Zheng
- Department of Chemistry, University of Texas at Dallas, 800 W Campbell Rd, Richardson, TX, 75080, USA. ; Tel: +1-972-883-5768; Fax: +1-972-883-2925
| |
Collapse
|
25
|
Nie S, Wang X, Li J, Clinite R, Cao J. Femtosecond electron diffraction: direct probe of ultrafast structural dynamics in metal films. Microsc Res Tech 2009; 72:131-43. [PMID: 19130610 DOI: 10.1002/jemt.20666] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Femtosecond electron diffraction is a rapidly advancing technique that holds a great promise for studying ultrafast structural dynamics in phase transitions, chemical reactions, and function of biological molecules at the atomic time and length scales. In this paper, we summarize our development of a tabletop femtosecond electron diffractometer. Using a delicate instrument design and careful experimental configurations, we demonstrate the unprecedented capability of detecting submilli-ångström lattice spacing change on a subpicosecond timescale with this new technique. We have conducted an in-depth investigation of ultrafast coherent phonon dynamics induced by an impulsive optical excitation in thin-film metals. By probing both coherent acoustic and random thermal lattice motions simultaneously in real time, we have provided the first and unambiguous experimental evidence that the pressure of hot electrons contributes significantly to the generation of coherent acoustic phonons under nonequilibrium conditions when electrons and phonons are not thermalized. Based on these observations, we also propose an innovative approach to measure the electronic Grüneisen parameter in magnetic materials at and above room temperature, which provides a way to gain new insights into electronic thermal expansion in ferromagnetic transition metals.
Collapse
Affiliation(s)
- Shouhua Nie
- Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | | | | | | | | |
Collapse
|
26
|
Hopkins PE, Klopf JM, Norris PM. Influence of interband transitions on electron-phonon coupling measurements in Ni films. Appl Opt 2007; 46:2076-83. [PMID: 17384723 DOI: 10.1364/ao.46.002076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The reduction in size and the increase in speed of opto- and magnetoelectronic devices is making the probability of nonequilibrium electron-phonon phenomena greater, leading to increased thermal resistance in these devices. The measurement of electron-phonon coupling in materials in these devices is becoming increasingly important for accurate thermal management. Here femtosecond thermoreflectance is used to measure the electron-phonon coupling factor in thin Ni films of varying thickness grown on Si and glass substrates. The thermoreflectance response is measured at 1.3 and 1.55 eV, yielding drastically different responses due to the Fermi-level transition at 1.3 eV in Ni. The influence of this transition on the thermoreflectance response results in a measurement of the electron-phonon coupling factor that is twice as high as that recorded in previous measurements that were unaffected by the Fermi-level transition.
Collapse
Affiliation(s)
- Patrick E Hopkins
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA 22904-4746, USA
| | | | | |
Collapse
|
27
|
Maier M, Wrigge G, Hoffmann MA, Didier P, von Issendorff B. Observation of electron gas cooling in free sodium clusters. Phys Rev Lett 2006; 96:117405. [PMID: 16605872 DOI: 10.1103/physrevlett.96.117405] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2005] [Indexed: 05/08/2023]
Abstract
Free size-selected Na+(n) (n = 16-250) clusters have been studied by femtosecond pump-probe photoelectron and photofragmentation spectroscopy. Thermal electron emission from the hot electron gas was used to monitor the energy transfer from the electronic system to lattice vibrations. The electron-phonon coupling constants determined for the different sizes can be described by the radius dependent function g(R) = (2.3 + 114 A2/R2) X 10(16) W/m3K. No strong quantum size effect was observed even for the smallest cluster size.
Collapse
Affiliation(s)
- M Maier
- Fakultät für Physik, Universität Freiburg, Stefan-Meier-Strasse 21, D-79104 Freiburg, Germany
| | | | | | | | | |
Collapse
|
28
|
Nie S, Wang X, Park H, Clinite R, Cao J. Measurement of the electronic Grüneisen constant using femtosecond electron diffraction. Phys Rev Lett 2006; 96:025901. [PMID: 16486599 DOI: 10.1103/physrevlett.96.025901] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Indexed: 05/06/2023]
Abstract
We report the first accurate measurement of the electronic Grüneisen constant gamma(e) using a novel method employing the new technique of femtosecond electron diffraction. The contributions of the conduction electrons and the lattice to thermal expansion are differentiated in the time domain through transiently heating the electronic temperature well above that of the lattice with femtosecond optical pulses. By directly probing the associated thermal expansion dynamics in real time using femtosecond electron diffraction, we are able to separate the contributions of hot electrons from that of lattice heating, and make an accurate measurement of gamma(e) of aluminum at room temperature. This new approach opens the possibility of distinguishing electronic from magnetic contributions to thermal expansion in magnetic materials at low temperature.
Collapse
Affiliation(s)
- Shouhua Nie
- Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | | | | | | | | |
Collapse
|
29
|
|
30
|
|
31
|
Hodak JH, Henglein A, Hartland GV. Electron-phonon coupling dynamics in very small (between 2 and 8 nm diameter) Au nanoparticles. J Chem Phys 2000. [DOI: 10.1063/1.481167] [Citation(s) in RCA: 183] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|