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Chinese Physics B 2014年第7期23卷 573-578页

作者：王党朝张玉明 School of Physics and Electronic Engineering Xianyang Normal University School of Microelectronics Xidian University Key Laboratory of Wide Band-gap Semiconductor Materials and Devices Xidian University

We produced epitaxial graphene under a moderate pressure of 4 mbar （about 400 Pa） at temperature 1600 ℃. Raman spectroscopy and optical microscopy were used to confirm that epitaxial graphene has taken shape continually with slight thickness variations and regularly with a centimeter order of magnitude on 4H-SiC （0001） substrates. Then using X-ray photoelectron spectroscopy and Auger electron spectroscopy, we analyzed the chemical compositions and estimated the layer number of epitaxial graphene. Finally, an atomic force microscope and a scanning force microscope were used to characterize the morphological structure. Our results showed that under 4-mbar pressure, epitaxial graphene could be produced on a SiC substrate with a large area, uniform thickness but a limited morphological property. We hope our work will be of benefit to understanding the formation process of epitaxial graphene on SiC substrate in detail.

关键词： SiC substrate graphene epitaxial graphene

Temperature dependence of the thickness and morphology of epitaxial graphene grown on SiC (0001) wafers

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Chinese Physics B 2012年第4期21卷 438-441页

作者：郝昕陈远富李萍剑王泽高刘竞博贺加瑞樊睿孙继荣张万里李言荣 State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 610054China Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China

Epitaxiai graphene is synthesized by silicon sublimation from the Si-terminated 6H SiC substrate. The effects of graphitization temperature on the thickness and surface morphology of epitaxial graphene are investigated. X-ray photoelectron spectroscopy spectra and atomic force microscopy images reveal that the epitaxial graphene thickness increases and the epitaxial graphene roughness decreases with the increase in graphitization temperature. This means that the thickness and roughness of epitaxial graphene films can be modulated by varying the graphitization temperature. In addition, the electrical properties of epitaxial graphene film are also investigated by Hall effect measurement.

关键词： epitaxial graphene thickness morphology graphitization temperature

Raman analysis of epitaxial graphene grown on 4H-SiC (0001) substrate under low pressure condition

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Chinese Physics B 2011年第12期20卷 439-442页

作者：王党朝张玉明张义门雷天民郭辉王悦湖汤晓燕王航 School of Microelectronics Key Laboratory of Wide Band-Gap Semiconductor Materials and DevicesXidian University School of Physics and Electronic Engineering Xianyang Normal College

In this paper, we report a feasible route of growing epitaxial graphene on 4H-SiC （0001） substrate in a low pressure of 4 mbar （1 bar=105 Pa） with an argon flux of 2 standard liters per minute at 1200, 1300, 1400, and 1500 ℃ in a commercial chemical vapour deposition SiC reactor. Using Raman spectroscopy and scanning electron microscopy, we confirm that epitaxial graphene evidently forms on SiC surface above 1300 ℃ with a size of several microns. By fitting the 2D band of Raman data with two-Lorentzian function, and comparing with the published reports, we conclude that epitaxial graphene grown at 1300 ℃ is four-layer graphene.

关键词： SiC substrate epitaxial graphene Raman spectroscopy

Effect of 6H-SiC (1120) substrate on epitaxial graphene revealed by Raman scattering

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Chinese Physics B 2013年第1期22卷 27-32页

作者：林菁菁郭丽伟贾玉萍陈莲莲芦伟黄郊陈小龙 Research & Development Center for Functional Crystals Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences

A nonpolar SiC（1120） substrate has been used to fabricate epitaxial graphene （EG）. Two EGs with layer numbers of 8-10 （referred to as MLG） and 2-3 （referred to as FLG） were used as representative to study the substrate effect on EG through temperature-dependent Raman scattering. It is found that Raman lineshifts of G and 2D peaks of the MLG with temperature are consistent with that of free graphene, as predicted by theory calculation, indicating that the substrate influence on the MLG is undetectable. While Raman G peak lineshifts of the FLG to that of the free graphene are obvious, however, its lineshift rate （-0.016 cm-1/K） is almost one third of that （-0.043 cm-1/K） of an EG on 6H-SiC （0001） in the temperature range from 300 K to 400 K, indicating a weak substrate effect from SiC （1120） on the FLG. This renders the FLG with a high mobility around 1812 cm2.V-1 .s -1 at room temperature even with a very high carrier concentration about 2.95 × 10 ^13 cm-2 （p-type）. These suggest SiC （1120） is more suitable for fabricating EG with high performance.

关键词： epitaxial graphene 6H-SiC (1120) temperature dependent Raman scattering

Er intercalation and its impact on transport properties of epitaxial graphene

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Chinese Physics B 2023年第6期32卷 404-409页

作者：杨明敏端勇孔雯霞章晋哲王剑心蔡群 State Key Laboratory of Surface Physics and Department of Physics Fudan UniversityShanghai 200433China

Intercalation of atomic species is a practicable method for epitaxial graphene to adjust the electronic band structure and to tune the coupling between graphene and Si C substrate. In this work, atomically flat epitaxial graphene is prepared on 4H-SiC(0001) using the flash heating method in an ultrahigh vacuum system. Scanning tunneling microscopy, Raman spectroscopy and electrical transport measurements are utilized to investigate surface morphological structures and transport properties of pristine and Er-intercalated epitaxial graphene. It is found that Er atoms are intercalated underneath the graphene layer after annealing at 900℃, and the intercalation sites of Er atoms are located mainly at the bufferlayer/monolayer-graphene interface in monolayer domains. We also report the different behaviors of Er intercalation in monolayer and bilayer regions, and the experimental results show that the diffusion barrier for Er intercalated atoms in the buffer-layer/monolayer interface is at least 0.2 eV higher than that in the first/second graphene-layer interface. The appearance of Er atoms is found to have distinct impacts on the electronic transports of epitaxial graphene on SiC(0001).

关键词： epitaxial graphene intercalation scanning tunneling microscopy(STM) electrical transport

A self-powered sensitive ultraviolet photodetector based on epitaxial graphene on silicon carbide

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Chinese Physics B 2016年第6期25卷 458-462页

作者：黄郊郭丽伟芦伟张永晖史哲贾玉萍李治林杨军伟陈洪祥梅增霞陈小龙 Research & Development Center for Functional Crystals Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Key Laboratory for Renewable Energy Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences Laboratory of Optical Physics Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of Sciences

A self-powered graphene-based photodetector with high performance is particularly useful for device miniaturization and to save ***,we report a graphene/silicon carbide（SiC）-based self-powered ultraviolet photodetector that exhibits a current responsivity of 7.4 m A/W with a response frequency of over a megahertz under 325-nm laser *** built-in photovoltage of the photodetector is about four orders of magnitude higher than previously reported results for similar *** favorable properties are ascribed to the ingenious device design using the combined advantages of graphene and SiC,two terminal electrodes,and asymmetric light irradiation on one of the ***,the photon energy is larger than the band gap of *** self-powered photodetector is compatible with modern semiconductor technology and shows potential for applications in ultraviolet imaging and graphene-based integrated circuits.

关键词： epitaxial graphene ultraviolet photodetector SiC self-powered

Significant photoelectrical response of epitaxial graphene grown on Si-terminated 6H-SiC

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Chinese Physics B 2013年第7期22卷 37-40页

作者：郝昕陈远富王泽高刘竞博贺加瑞李言荣 State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China

Photoelectrical response characteristics of epitaxial graphene （EG） films on Si- and C-terminated 6H-SiC, and transferred chemical vapor deposition （CVD） graphene films on Si-terminated 6H-SiC have been investigated. The results show that upon illumination by a xenon lamp, the photocurrent of EG grown on Si-terminated SiC significantly increases by 147.6%, while the photocurrents of EG grown on C-terminated SiC, and transferred CVD graphene on Si-terminated SiC slightly decrease by 0.5% and 2.7%, respectively. The interfacial buffer layer between EG and Si-terminated 6H-SiC is responsible for the significant photoelectrical response of EG. Its strong photoelectrical response makes it promising for optoelectronic applications.

关键词： epitaxial graphene photoelectrical response oxygen absorption

High temperature characteristics of bilayer epitaxial graphene field-effect transistors on SiC Substrate

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Chinese Physics B 2016年第6期25卷 463-467页

作者：何泽召杨克武蔚翠刘庆彬王晶晶李佳芦伟立冯志红蔡树军 School of Electronic and Information Engineering Hebei University of Technology Tianjin 300130 China National Key Laboratory of ASIC Hebei Semiconductor Research Institute Shijiazhuang 050051 China

In this paper,high temperature direct current（DC） performance of bilayer epitaxial graphene device on SiC substrate is studied in a temperature range from 25℃ to 200℃.At a gate voltage of-8 V（far from Dirac point）,the drainsource current decreases obviously with increasing temperature,but it has little change at a gate bias of ＋8 V（near Dirac point）.The competing interactions between scattering and thermal activation are responsible for the different reduction *** different kinds of scatterings are taken into account to qualitatively analyze the carrier mobility under different *** devices exhibit almost unchanged DC performances after high temperature measurements at 200℃ for 5 hours in air ambience,demonstrating the high thermal stabilities of the bilayer epitaxial graphene devices.

关键词： epitaxial graphene field-effect transistor high temperature characteristics

Raman analysis of epitaxial graphene on 6H-SiC(000) substrates under low pressure environment

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Journal of Semiconductors 2011年第11期32卷 39-42页

作者：王党朝张玉明张义门雷天民郭辉王悦湖汤晓燕王航 Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University School of Physics and Electronic Engineering Xianyang Normal College

This article investigates the formation mechanism of epitaxial graphene on 6H-SiC （0001） substrates under low pressure of 2 mbar environment. It is shown that the growth temperature dramatically affects the formation and quality of epitaxial graphene. The higher growing temperature is of great benefit to the quality of epitaxial graphene and also can reduce the impact of the substrate for graphene. By analyzing Raman data, we conclude that epitaxial graphene grown at 1600 ℃ has a turbostratic graphite structure. The test from scanning electron microscopy （SEM） indicates that the epitaxial graphene has a route for fabricating larger size of epitaxial graphene on SiC size of 10μm. This research will provide a feasible substrate.

关键词： epitaxial graphene Raman spectroscopy turbostratic graphite SiC

Comparison of the formation process and properties of epitaxial graphenes on Si-and C-face 6H-SiC substrates

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Chinese Physics B 2012年第3期21卷 480-483页

作者：王党朝张玉明张义门雷天民郭辉王悦湖汤晓燕王航 School of Microelectronics Xidian University Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices Xidian University School of Physics and Electronic Engineering Xianyang Normal College

In this paper,the epitaxial graphene layers grown on Si-and C-face 6H-SiC substrates are investigated under a low pressure of 400 Pa at 1600 *** using atomic force microscopy and Raman spectroscopy,we find that there are distinct differences in the formation and the properties between the epitaxial graphene layers grown on the Si-face and the C-face substrates,including the hydrogen etching process,the stacking type,and the number of ***,our results will be useful for improving the quality of the epitaxial graphene on SiC substrate.

关键词： SiC substrate epitaxial graphene Raman spectroscopy