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La Via F, Alquier D, Giannazzo F, Kimoto T, Neudeck P, Ou H, Roncaglia A, Saddow SE, Tudisco S. Emerging SiC Applications beyond Power Electronic Devices. MICROMACHINES 2023; 14:1200. [PMID: 37374785 DOI: 10.3390/mi14061200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/29/2023]
Abstract
In recent years, several new applications of SiC (both 4H and 3C polytypes) have been proposed in different papers. In this review, several of these emerging applications have been reported to show the development status, the main problems to be solved and the outlooks for these new devices. The use of SiC for high temperature applications in space, high temperature CMOS, high radiation hard detectors, new optical devices, high frequency MEMS, new devices with integrated 2D materials and biosensors have been extensively reviewed in this paper. The development of these new applications, at least for the 4H-SiC ones, has been favored by the strong improvement in SiC technology and in the material quality and price, due to the increasing market for power devices. However, at the same time, these new applications need the development of new processes and the improvement of material properties (high temperature packages, channel mobility and threshold voltage instability improvement, thick epitaxial layers, low defects, long carrier lifetime, low epitaxial doping). Instead, in the case of 3C-SiC applications, several new projects have developed material processes to obtain more performing MEMS, photonics and biomedical devices. Despite the good performance of these devices and the potential market, the further development of the material and of the specific processes and the lack of several SiC foundries for these applications are limiting further development in these fields.
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Affiliation(s)
| | - Daniel Alquier
- GREMAN, UMR 7347, Université de Tours, CNRS, 37071 Tours, France
| | | | - Tsunenobu Kimoto
- Department of Electronic Science and Engineering, Kyoto University, Nishikyo, Kyoto 615-8510, Japan
| | - Philip Neudeck
- NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, OH 44135, USA
| | - Haiyan Ou
- Department of Electrical and Photonics Engineering, Technical University of Denmark, Ørsteds Plads, Building 343, DK-2800 Kgs. Lyngby, Denmark
| | | | - Stephen E Saddow
- Electrical Engineering Department, University of South Florida, 4202 E. Fowler Avenue, ENG 030, Tampa, FL 33620, USA
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An epitaxial graphene platform for zero-energy edge state nanoelectronics. Nat Commun 2022; 13:7814. [PMID: 36535919 PMCID: PMC9763431 DOI: 10.1038/s41467-022-34369-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 10/24/2022] [Indexed: 12/23/2022] Open
Abstract
Graphene's original promise to succeed silicon faltered due to pervasive edge disorder in lithographically patterned deposited graphene and the lack of a new electronics paradigm. Here we demonstrate that the annealed edges in conventionally patterned graphene epitaxially grown on a silicon carbide substrate (epigraphene) are stabilized by the substrate and support a protected edge state. The edge state has a mean free path that is greater than 50 microns, 5000 times greater than the bulk states and involves a theoretically unexpected Majorana-like zero-energy non-degenerate quasiparticle that does not produce a Hall voltage. In seamless integrated structures, the edge state forms a zero-energy one-dimensional ballistic network with essentially dissipationless nodes at ribbon-ribbon junctions. Seamless device structures offer a variety of switching possibilities including quantum coherent devices at low temperatures. This makes epigraphene a technologically viable graphene nanoelectronics platform that has the potential to succeed silicon nanoelectronics.
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3
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Bugnet M, Ederer M, Lazarov VK, Li L, Ramasse QM, Löffler S, Kepaptsoglou DM. Imaging the Spatial Distribution of Electronic States in Graphene Using Electron Energy-Loss Spectroscopy: Prospect of Orbital Mapping. PHYSICAL REVIEW LETTERS 2022; 128:116401. [PMID: 35363018 DOI: 10.1103/physrevlett.128.116401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 12/23/2021] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
The spatial distributions of antibonding π^{*} and σ^{*} states in epitaxial graphene multilayers are mapped using electron energy-loss spectroscopy in a scanning transmission electron microscope. Inelastic channeling simulations validate the interpretation of the spatially resolved signals in terms of electronic orbitals, and demonstrate the crucial effect of the material thickness on the experimental capability to resolve the distribution of unoccupied states. This work illustrates the current potential of core-level electron energy-loss spectroscopy towards the direct visualization of electronic orbitals in a wide range of materials, of huge interest to better understand chemical bonding among many other properties at interfaces and defects in solids.
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Affiliation(s)
- M Bugnet
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
- Univ Lyon, CNRS, INSA Lyon, UCBL, MATEIS, UMR 5510, 69621 Villeurbanne, France
| | - M Ederer
- University Service Centre for Transmission Electron Microscopy, TU Wien, Wiedner Hauptstraße 8-10/E057-02, 1040 Wien, Austria
| | - V K Lazarov
- Department of Physics, University of York, York YO10 5DD, United Kingdom
| | - L Li
- Department of Physics and Astronomy, University of West Virginia, Morgantown, West Virginia 26506, USA
| | - Q M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - S Löffler
- University Service Centre for Transmission Electron Microscopy, TU Wien, Wiedner Hauptstraße 8-10/E057-02, 1040 Wien, Austria
| | - D M Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, United Kingdom
- Department of Physics, University of York, York YO10 5DD, United Kingdom
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Panna AR, Hu IF, Kruskopf M, Patel DK, Jarrett DG, Liu CI, Payagala SU, Saha D, Rigosi AF, Newell DB, Liang CT, Elmquist RE. Graphene quantum Hall effect parallel resistance arrays. PHYSICAL REVIEW. B 2021; 103:10.1103/physrevb.103.075408. [PMID: 34263094 PMCID: PMC8276113 DOI: 10.1103/physrevb.103.075408] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
As first recognized in 2010, epitaxial graphene on SiC(0001) provides a platform for quantized Hall resistance (QHR) metrology unmatched by other two-dimensional structures and materials. Here we report graphene parallel QHR arrays, with metrologically precise quantization near 1000 Ω. These arrays have tunable carrier densities, due to uniform epitaxial growth and chemical functionalization, allowing quantization at the robust ν = 2 filling factor in array devices at relative precision better than 10-8. Broad tunability of the carrier density also enables investigation of the ν = 6 plateau. Optimized networks of QHR devices described in this work suppress Ohmic contact resistance error using branched contacts and avoid crossover leakage with interconnections that are superconducting for quantizing magnetic fields up to 13.5 T. Our work enables more direct scaling of resistance for quantized values in arrays of arbitrary network geometry.
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Affiliation(s)
- Alireza R Panna
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
| | - I-Fan Hu
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan, Republic of China
| | - Mattias Kruskopf
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
| | - Dinesh K Patel
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan, Republic of China
| | - Dean G Jarrett
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
| | - Chieh-I Liu
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - Shamith U Payagala
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
| | - Dipanjan Saha
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
| | - Albert F Rigosi
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
| | - David B Newell
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
| | - Chi-Te Liang
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan, Republic of China
| | - Randolph E Elmquist
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899-8171, USA
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Giannazzo F, Dagher R, Schilirò E, Panasci SE, Greco G, Nicotra G, Roccaforte F, Agnello S, Brault J, Cordier Y, Michon A. Nanoscale structural and electrical properties of graphene grown on AlGaN by catalyst-free chemical vapor deposition. NANOTECHNOLOGY 2021; 32:015705. [PMID: 33043906 DOI: 10.1088/1361-6528/abb72b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The integration of graphene (Gr) with nitride semiconductors is highly interesting for applications in high-power/high-frequency electronics and optoelectronics. In this work, we demonstrated the direct growth of Gr on Al0.5Ga0.5N/sapphire templates by propane (C3H8) chemical vapor deposition at a temperature of 1350 °C. After optimization of the C3H8 flow rate, a uniform and conformal Gr coverage was achieved, which proved beneficial to prevent degradation of AlGaN morphology. X-ray photoemission spectroscopy revealed Ga loss and partial oxidation of Al in the near-surface AlGaN region. Such chemical modification of a ∼2 nm thick AlGaN surface region was confirmed by cross-sectional scanning transmission electron microscopy combined with electron energy loss spectroscopy, which also showed the presence of a bilayer of Gr with partial sp2/sp3 hybridization. Raman spectra indicated that the deposited Gr is nanocrystalline (with domain size ∼7 nm) and compressively strained. A Gr sheet resistance of ∼15.8 kΩ sq-1 was evaluated by four-point-probe measurements, consistently with the nanocrystalline nature of these films. Furthermore, nanoscale resolution current mapping by conductive atomic force microscopy indicated local variations of the Gr carrier density at a mesoscopic scale, which can be ascribed to changes in the charge transfer from the substrate due to local oxidation of AlGaN or to the presence of Gr wrinkles.
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Affiliation(s)
- F Giannazzo
- Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII, n. 5 Zona Industriale, 95121, Catania, Italy
| | - R Dagher
- Université Côte d'Azur, CNRS, CRHEA, Rue Bernard Grégory, 06560, Valbonne, France
| | - E Schilirò
- Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII, n. 5 Zona Industriale, 95121, Catania, Italy
| | - S E Panasci
- Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII, n. 5 Zona Industriale, 95121, Catania, Italy
- Department of Physics and Astronomy, University of Catania, via Santa Sofia 64, 95123, Catania, Italy
| | - G Greco
- Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII, n. 5 Zona Industriale, 95121, Catania, Italy
| | - G Nicotra
- Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII, n. 5 Zona Industriale, 95121, Catania, Italy
| | - F Roccaforte
- Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII, n. 5 Zona Industriale, 95121, Catania, Italy
| | - S Agnello
- Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII, n. 5 Zona Industriale, 95121, Catania, Italy
- Department of Physics and Chemistry 'E. Segrè', University of Palermo, via Archirafi 36, 90123, Palermo, Italy
| | - J Brault
- Université Côte d'Azur, CNRS, CRHEA, Rue Bernard Grégory, 06560, Valbonne, France
| | - Y Cordier
- Université Côte d'Azur, CNRS, CRHEA, Rue Bernard Grégory, 06560, Valbonne, France
| | - A Michon
- Université Côte d'Azur, CNRS, CRHEA, Rue Bernard Grégory, 06560, Valbonne, France
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Giannazzo F, Schilirò E, Greco G, Roccaforte F. Conductive Atomic Force Microscopy of Semiconducting Transition Metal Dichalcogenides and Heterostructures. NANOMATERIALS 2020; 10:nano10040803. [PMID: 32331313 PMCID: PMC7221570 DOI: 10.3390/nano10040803] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 11/16/2022]
Abstract
Semiconducting transition metal dichalcogenides (TMDs) are promising materials for future electronic and optoelectronic applications. However, their electronic properties are strongly affected by peculiar nanoscale defects/inhomogeneities (point or complex defects, thickness fluctuations, grain boundaries, etc.), which are intrinsic of these materials or introduced during device fabrication processes. This paper reviews recent applications of conductive atomic force microscopy (C-AFM) to the investigation of nanoscale transport properties in TMDs, discussing the implications of the local phenomena in the overall behavior of TMD-based devices. Nanoscale resolution current spectroscopy and mapping by C-AFM provided information on the Schottky barrier uniformity and shed light on the mechanisms responsible for the Fermi level pinning commonly observed at metal/TMD interfaces. Methods for nanoscale tailoring of the Schottky barrier in MoS2 for the realization of ambipolar transistors are also illustrated. Experiments on local conductivity mapping in monolayer MoS2 grown by chemical vapor deposition (CVD) on SiO2 substrates are discussed, providing a direct evidence of the resistance associated to the grain boundaries (GBs) between MoS2 domains. Finally, C-AFM provided an insight into the current transport phenomena in TMD-based heterostructures, including lateral heterojunctions observed within MoxW1-xSe2 alloys, and vertical heterostructures made by van der Waals stacking of different TMDs (e.g., MoS2/WSe2) or by CVD growth of TMDs on bulk semiconductors.
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7
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Atomic Layer Deposition of High-k Insulators on Epitaxial Graphene: A Review. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10072440] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Due to its excellent physical properties and availability directly on a semiconductor substrate, epitaxial graphene (EG) grown on the (0001) face of hexagonal silicon carbide is a material of choice for advanced applications in electronics, metrology and sensing. The deposition of ultrathin high-k insulators on its surface is a key requirement for the fabrication of EG-based devices, and, in this context, atomic layer deposition (ALD) is the most suitable candidate to achieve uniform coating with nanometric thickness control. This paper presents an overview of the research on ALD of high-k insulators on EG, with a special emphasis on the role played by the peculiar electrical/structural properties of the EG/SiC (0001) interface in the nucleation step of the ALD process. The direct deposition of Al2O3 thin films on the pristine EG surface will be first discussed, demonstrating the critical role of monolayer EG uniformity to achieve a homogeneous Al2O3 coverage. Furthermore, the ALD of several high-k materials on EG coated with different seeding layers (oxidized metal films, directly deposited metal-oxides and self-assembled organic monolayers) or subjected to various prefunctionalization treatments (e.g., ozone or fluorine treatments) will be presented. The impact of the pretreatments and of thermal ALD growth on the defectivity and electrical properties (doping and carrier mobility) of the underlying EG will be discussed.
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Manetoresistance of Ultralow-Hole-Density Monolayer Epitaxial Graphene Grown on SiC. MATERIALS 2019; 12:ma12172696. [PMID: 31450728 PMCID: PMC6747865 DOI: 10.3390/ma12172696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 08/15/2019] [Accepted: 08/21/2019] [Indexed: 11/23/2022]
Abstract
Silicon carbide (SiC) has already found useful applications in high-power electronic devices and light-emitting diodes (LEDs). Interestingly, SiC is a suitable substrate for growing monolayer epitaxial graphene and GaN-based devices. Therefore, it provides the opportunity for integration of high-power devices, LEDs, atomically thin electronics, and high-frequency devices, all of which can be prepared on the same SiC substrate. In this paper, we concentrate on detailed measurements on ultralow-density p-type monolayer epitaxial graphene, which has yet to be extensively studied. The measured resistivity ρxx shows insulating behavior in the sense that ρxx decreases with increasing temperature T over a wide range of T (1.5 K ≤ T ≤ 300 K). The crossover from negative magnetoresistivity (MR) to positive magnetoresistivity at T = 40 K in the low-field regime is ascribed to a transition from low-T quantum transport to high-T classical transport. For T ≥ 120 K, the measured positive MR ratio [ρxx(B) − ρxx(B = 0)]/ρxx(B = 0) at B = 2 T decreases with increasing T, but the positive MR persists up to room temperature. Our experimental results suggest that the large MR ratio (~100% at B = 9 T) is an intrinsic property of ultralow-charge-density graphene, regardless of the carrier type. This effect may find applications in magnetic sensors and magnetoresistance devices.
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Whelan PR, Panchal V, Petersen DH, Mackenzie DMA, Melios C, Pasternak I, Gallop J, Østerberg FW, U Jepsen P, Strupinski W, Kazakova O, Bøggild P. Electrical Homogeneity Mapping of Epitaxial Graphene on Silicon Carbide. ACS APPLIED MATERIALS & INTERFACES 2018; 10:31641-31647. [PMID: 30130090 DOI: 10.1021/acsami.8b11428] [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
Epitaxial graphene is a promising route to wafer-scale production of electronic graphene devices. Chemical vapor deposition of graphene on silicon carbide offers epitaxial growth with layer control but is subject to significant spatial and wafer-to-wafer variability. We use terahertz time-domain spectroscopy and micro four-point probes to analyze the spatial variations of quasi-freestanding bilayer graphene grown on 4 in. silicon carbide (SiC) wafers and find significant variations in electrical properties across large regions, which are even reproduced across graphene on different SiC wafers cut from the same ingot. The dc sheet conductivity of epitaxial graphene was found to vary more than 1 order of magnitude across a 4 in. SiC wafer. To determine the origin of the variations, we compare different optical and scanning probe microscopies with the electrical measurements from nano- to millimeter scale and identify three distinct qualities of graphene, which can be attributed to the microstructure of the SiC surface.
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Affiliation(s)
- Patrick R Whelan
- DTU Fotonik , Technical University of Denmark , Ørsteds Plads 343 , DK-2800 Kongens Lyngby , Denmark
| | - Vishal Panchal
- National Physical Laboratory , Hampton Road , Teddington TW11 0LW , U.K
| | | | | | - Christos Melios
- National Physical Laboratory , Hampton Road , Teddington TW11 0LW , U.K
| | - Iwona Pasternak
- Faculty of Physics , Warsaw University of Technology , Koszykowa 75 , 00-662 Warsaw , Poland
| | - John Gallop
- National Physical Laboratory , Hampton Road , Teddington TW11 0LW , U.K
| | | | - Peter U Jepsen
- DTU Fotonik , Technical University of Denmark , Ørsteds Plads 343 , DK-2800 Kongens Lyngby , Denmark
| | - Wlodek Strupinski
- Faculty of Physics , Warsaw University of Technology , Koszykowa 75 , 00-662 Warsaw , Poland
| | - Olga Kazakova
- National Physical Laboratory , Hampton Road , Teddington TW11 0LW , U.K
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11
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Yang Y, Cheng G, Mende P, Calizo IG, Feenstra RM, Chuang C, Liu CW, Liu CI, Jones GR, Hight Walker AR, Elmquist RE. Epitaxial graphene homogeneity and quantum Hall effect in millimeter-scale devices. CARBON 2017; 115:229-236. [PMID: 28924301 PMCID: PMC5600207 DOI: 10.1016/j.carbon.2016.12.087] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Quantized magnetotransport is observed in 5.6 × 5.6 mm2 epitaxial graphene devices, grown using highly constrained sublimation on the Si-face of SiC(0001) at high temperature (1900 °C). The precise quantized Hall resistance of [Formula: see text] is maintained up to record level of critical current Ixx = 0.72 mA at T = 3.1 K and 9 T in a device where Raman microscopy reveals low and homogeneous strain. Adsorption-induced molecular doping in a second device reduced the carrier concentration close to the Dirac point (n ≈ 1010 cm-2), where mobility of 18760 cm2/V is measured over an area of 10 mm2. Atomic force, confocal optical, and Raman microscopies are used to characterize the large-scale devices, and reveal improved SiC terrace topography and the structure of the graphene layer. Our results show that the structural uniformity of epitaxial graphene produced by face-to-graphite processing contributes to millimeter-scale transport homogeneity, and will prove useful for scientific and commercial applications.
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Affiliation(s)
- Yanfei Yang
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
| | - Guangjun Cheng
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
| | - Patrick Mende
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA
| | - Irene G. Calizo
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
| | - Randall M. Feenstra
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USA
| | - Chiashain Chuang
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
| | - Chieh-Wen Liu
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
- Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan
| | - Chieh-I. Liu
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
- Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan
| | - George R. Jones
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
| | | | - Randolph E. Elmquist
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8171, USA
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12
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Caporali M, Serrano-Ruiz M, Telesio F, Heun S, Nicotra G, Spinella C, Peruzzini M. Decoration of exfoliated black phosphorus with nickel nanoparticles and its application in catalysis. Chem Commun (Camb) 2017; 53:10946-10949. [DOI: 10.1039/c7cc05906j] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new surface functionalization of exfoliated black phosphorus has been carried out with Ni nanoparticles. The nanohybrid catalyzed the semihydrogenation of phenylacetylene achieving high selectivity to styrene.
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Affiliation(s)
| | | | - Francesca Telesio
- NEST
- Istituto Nanoscienze-CNR and Scuola Normale Superiore
- 56127 Pisa
- Italy
| | - Stefan Heun
- NEST
- Istituto Nanoscienze-CNR and Scuola Normale Superiore
- 56127 Pisa
- Italy
| | - Giuseppe Nicotra
- CNR-IMM
- Istituto per la Microelettronica e Microsistemi
- 95121 Catania
- Italy
| | - Corrado Spinella
- CNR-IMM
- Istituto per la Microelettronica e Microsistemi
- 95121 Catania
- Italy
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13
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14
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Giannazzo F. Insight into the mechanisms of chemical doping of graphene on silicon carbide. NANOTECHNOLOGY 2016; 27:072502. [PMID: 26782771 DOI: 10.1088/0957-4484/27/7/072502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Graphene (Gr) is currently the object of intense research investigations, owing to its rich physics and wide potential for applications. In particular, epitaxial Gr on silicon carbide (SiC) holds great promise for the development of new device concepts based on the vertical current transport at Gr/SiC heterointerface. Precise tailoring of Gr workfunction (WF) represents a key requirement for these device structures. In this context, Günes et al (2015 Nanotechnology 26 445702) recently reported a straightforward approach for WF modulation in epitaxial Gr on silicon carbide by using nitric acid solutions at different dilutions. This paper provides a deep insight on the peculiar mechanisms of chemical doping of epitaxial Gr on 4H-SiC(0001), using several characterization techniques (Raman, UPS, AFM) and density functional theory calculations. The relevance of these findings and their perspective applications in emerging device concepts based on monolithic integration of Gr and SiC will be discussed.
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15
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Functionalized graphene as a model system for the two-dimensional metal-insulator transition. Sci Rep 2016; 6:19939. [PMID: 26860789 PMCID: PMC4748216 DOI: 10.1038/srep19939] [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: 09/10/2015] [Accepted: 11/30/2015] [Indexed: 11/22/2022] Open
Abstract
Reports of metallic behavior in two-dimensional (2D) systems such as high mobility metal-oxide field effect transistors, insulating oxide interfaces, graphene, and MoS2 have challenged the well-known prediction of Abrahams, et al. that all 2D systems must be insulating. The existence of a metallic state for such a wide range of 2D systems thus reveals a wide gap in our understanding of 2D transport that has become more important as research in 2D systems expands. A key to understanding the 2D metallic state is the metal-insulator transition (MIT). In this report, we explore the nature of a disorder induced MIT in functionalized graphene, a model 2D system. Magneto-transport measurements show that weak-localization overwhelmingly drives the transition, in contradiction to theoretical assumptions that enhanced electron-electron interactions dominate. These results provide the first detailed picture of the nature of the transition from the metallic to insulating states of a 2D system.
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16
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Sun L, Chen X, Yu W, Sun H, Zhao X, Xu X, Yu F, Liu Y. The effect of the surface energy and structure of the SiC substrate on epitaxial graphene growth. RSC Adv 2016. [DOI: 10.1039/c6ra21858j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The theoretical calculations and experiments were employed to study the effect of the exposed SiC surface on epitaxial graphene growth.
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Affiliation(s)
- Li Sun
- State Key Laboratory of Crystal Materials
- Shandong University
- Jinan
- China
| | - Xiufang Chen
- State Key Laboratory of Crystal Materials
- Shandong University
- Jinan
- China
| | - Wancheng Yu
- State Key Laboratory of Crystal Materials
- Shandong University
- Jinan
- China
| | - Honggang Sun
- School of Mechanical, Electrical & Information Engineering
- Shandong University
- Weihai
- China
| | - Xian Zhao
- State Key Laboratory of Crystal Materials
- Shandong University
- Jinan
- China
| | - Xiangang Xu
- State Key Laboratory of Crystal Materials
- Shandong University
- Jinan
- China
| | - Fan Yu
- Institute of Optics and Electronics
- Chinese Academy of Science
- Chengdu
- China
| | - Yunfeng Liu
- Institute of Optics and Electronics
- Chinese Academy of Science
- Chengdu
- China
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17
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Torrisi G, Di Mauro A, Scuderi M, Nicotra G, Impellizzeri G. Atomic layer deposition of ZnO/TiO2 multilayers: towards the understanding of Ti-doping in ZnO thin films. RSC Adv 2016. [DOI: 10.1039/c6ra13773c] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Undoped and Ti-doped ZnO (TZO) films were deposited by atomic layer deposition (ALD).
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Affiliation(s)
- G. Torrisi
- Dipartimento di Fisica e Astronomia
- Università degli Studi di Catania
- 95123 Catania
- Italy
- CNR-IMM
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18
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Günes F, Arezki H, Pierucci D, Alamarguy D, Alvarez J, Kleider JP, Dappe YJ, Ouerghi A, Boutchich M. Tuning the work function of monolayer graphene on 4H-SiC (0001) with nitric acid. NANOTECHNOLOGY 2015; 26:445702. [PMID: 26457876 DOI: 10.1088/0957-4484/26/44/445702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Chemical doping of graphene is a key process for the modulation of its electronic properties and the design and fabrication of graphene-based nanoelectronic devices. Here, we study the adsorption of diluted concentrations of nitric acid (HNO3) onto monolayer graphene/4H-SiC (0001) to induce a variation of the graphene work function (WF). Raman spectroscopy indicates an increase in the defect density subsequent to the doping. Moreover, ultraviolet photoemission spectroscopy (UPS) was utilized to quantify the WF shift. UPS data show that the WF of the graphene layer decreased from 4.3 eV (pristine) down to 3.8 eV (30% HNO3) and then increased to 4.4 eV at 100% HNO3 concentration. These observations were confirmed using density functional theory (DFT) calculations. This straightforward process allows a large WF modulation, rendering the molecularly modified graphene/4H-SiC(0001) a highly suitable electron or hole injection electrode.
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Affiliation(s)
- Fethullah Günes
- GeePs, CNRS UMR8507, CentraleSupelec, Univ Paris-Sud, Sorbonne Universités-UPMC Univ Paris 06, 11 rue Joliot-Curie, Plateau de Moulon, 91192 Gif-sur-Yvette Cedex, France. Department of Materials Science and Engineering, Izmir Kâtip Çelebi University Cigli Main Campus, 35620, IZMIR, Turkey
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19
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Liu X, Chen Y, Sun C, Guan M, Zhang Y, Zhang F, Sun G, Zeng Y. Surface Evolution of Nano-Textured 4H-SiC Homoepitaxial Layers after High Temperature Treatments: Morphology Characterization and Graphene Growth. NANOMATERIALS 2015; 5:1532-1543. [PMID: 28347079 PMCID: PMC5304623 DOI: 10.3390/nano5031532] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 11/29/2022]
Abstract
Nano-textured 4H–SiC homoepitaxial layers (NSiCLs) were grown on 4H–SiC(0001) substrates using a low pressure chemical vapor deposition technique (LPCVD), and subsequently were subjected to high temperature treatments (HTTs) for investigation of their surface morphology evolution and graphene growth. It was found that continuously distributed nano-scale patterns formed on NSiCLs which were about submicrons in-plane and about 100 nanometers out-of-plane in size. After HTTs under vacuum, pattern sizes reduced, and the sizes of the remains were inversely proportional to the treatment time. Referring to Raman spectra, the establishment of multi-layer graphene (MLG) on NSiCL surfaces was observed. MLG with sp2 disorders was obtained from NSiCLs after a high temperature treatment under vacuum at 1700 K for two hours, while MLG without sp2 disorders was obtained under Ar atmosphere at 1900 K.
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Affiliation(s)
- Xingfang Liu
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China.
| | - Yu Chen
- Semiconductor Lighting Technology Research and Development Center, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China.
| | - Changzheng Sun
- Tsinghua National Laboratory for Information Science and Technology, Tsinghua University, Beijing 100084, China.
| | - Min Guan
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China.
| | - Yang Zhang
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China.
| | - Feng Zhang
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China.
| | - Guosheng Sun
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China.
| | - Yiping Zeng
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China.
- Semiconductor Lighting Technology Research and Development Center, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China.
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20
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Synthesis of quasi-free-standing bilayer graphene nanoribbons on SiC surfaces. Nat Commun 2015; 6:7632. [PMID: 26158645 PMCID: PMC4510648 DOI: 10.1038/ncomms8632] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 05/26/2015] [Indexed: 11/30/2022] Open
Abstract
Scaling graphene down to nanoribbons is a promising route for the implementation of this material into devices. Quantum confinement of charge carriers in such nanostructures, combined with the electric field-induced break of symmetry in AB-stacked bilayer graphene, leads to a band gap wider than that obtained solely by this symmetry breaking. Consequently, the possibility of fabricating AB-stacked bilayer graphene nanoribbons with high precision is very attractive for the purposes of applied and basic science. Here we show a method, which includes a straightforward air annealing, for the preparation of quasi-free-standing AB-bilayer nanoribbons with different widths on SiC(0001). Furthermore, the experiments reveal that the degree of disorder at the edges increases with the width, indicating that the narrower nanoribbons are more ordered in their edge termination. In general, the reported approach is a viable route towards the large-scale fabrication of bilayer graphene nanostructures with tailored dimensions and properties for specific applications. Bilayer graphene nanoribbons are very promising for future nanoelectronics. Here Lopes et al. show a novel approach for the fabrication of quasi-free-standing bilayer graphene nanoribbons on SiC, based on the precise control of the layer-by-layer growth of graphene and a simple annealing step in air.
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21
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Palacio I, Celis A, Nair MN, Gloter A, Zobelli A, Sicot M, Malterre D, Nevius MS, de Heer WA, Berger C, Conrad EH, Taleb-Ibrahimi A, Tejeda A. Atomic structure of epitaxial graphene sidewall nanoribbons: flat graphene, miniribbons, and the confinement gap. NANO LETTERS 2015; 15:182-189. [PMID: 25457853 DOI: 10.1021/nl503352v] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Graphene nanoribbons grown on sidewall facets of SiC have demonstrated exceptional quantized ballistic transport up to 15 μm at room temperature. Angular-resolved photoemission spectroscopy (ARPES) has shown that the ribbons have the band structure of charge neutral graphene, while bent regions of the ribbon develop a bandgap. We present scanning tunneling microscopy and transmission electron microscopy of armchair nanoribbons grown on recrystallized sidewall trenches etched in SiC. We show that the nanoribbons consist of a single graphene layer essentially decoupled from the facet surface. The nanoribbons are bordered by 1-2 nm wide bent miniribbons at both the top and bottom edges of the nanoribbons. We establish that nanoscale confinement in the graphene miniribbons is the origin of the local large band gap observed in ARPES. The structural results presented here show how this gap is formed and provide a framework to help understand ballistic transport in sidewall graphene.
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Affiliation(s)
- Irene Palacio
- UR1 CNRS/Synchrotron SOLEIL , Saint-Aubin, 91192 Gif sur Yvette, France
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22
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Clark KW, Zhang XG, Vlassiouk IV, He G, Feenstra RM, Li AP. Spatially resolved mapping of electrical conductivity across individual domain (grain) boundaries in graphene. ACS NANO 2013; 7:7956-66. [PMID: 23952068 DOI: 10.1021/nn403056k] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
All large-scale graphene films contain extended topological defects dividing graphene into domains or grains. Here, we spatially map electronic transport near specific domain and grain boundaries in both epitaxial graphene grown on SiC and CVD graphene on Cu subsequently transferred to a SiO2 substrate, with one-to-one correspondence to boundary structures. Boundaries coinciding with the substrate step on SiC exhibit a significant potential barrier for electron transport of epitaxial graphene due to the reduced charge transfer from the substrate near the step edge. Moreover, monolayer-bilayer boundaries exhibit a high resistance that can change depending on the height of substrate step coinciding at the boundary. In CVD graphene, the resistance of a grain boundary changes with the width of the disordered transition region between adjacent grains. A quantitative modeling of boundary resistance reveals the increased electron Fermi wave vector within the boundary region, possibly due to boundary induced charge density variation. Understanding how resistance change with domain (grain) boundary structure in graphene is a crucial first step for controlled engineering of defects in large-scale graphene films.
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Affiliation(s)
- Kendal W Clark
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
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