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two-dimensional electron gas characteristics of InP-based high electron mobility transistor terahertz detector

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Chinese Physics B 2018年第4期27卷 363-368页

作者：李金伦崔少辉徐建星崔晓然郭春妍马奔倪海桥牛智川 Department of Missile Engineering Shijiazhuang CampusArmy Engineering University State Key Laboratory for Superlattices Institute of SemiconductorsChinese Academy of Sciences(CAS) Microsystem & Terahertz Research Center China Academy of Engineering Physics Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory Xidian University Key Laboratory of Ultra-fast Photoelectric Diagnostics Technology of Chinese Academy of Sciences Xi'an Institute of Optics and Precision Mechanics College of Materials Science and Opto-electronic Technology University of Chinese Academy of Sciences

The samples of InxGa（1-x）As/In（0.52）Al（0.48）As two-dimensional electron gas（2DEG）are grown by molecular beam epitaxy（MBE）.In the sample preparation process,the In content and spacer layer thickness are changed and two kinds of methods,i.e.,contrast body doping andδ-doping are used.The samples are analyzed by the Hall measurements at 300 Kand 77 K.The InxGa1-xAs/In0.52Al0.48As 2DEG channel structures with mobilities as high as 10289 cm^2/V·s（300 K）and42040 cm^2/V·s（77 K）are obtained,and the values of carrier concentration（Nc）are 3.465×10^12/cm^2 and 2.502×10^12/cm^2,respectively.The THz response rates of In P-based high electron mobility transistor（HEMT）structures with different gate lengths at 300 K and 77 K temperatures are calculated based on the shallow water wave instability theory.The results provide a reference for the research and preparation of In P-based HEMT THz detectors.

关键词： THz detector high electron mobility transistor two-dimensional electron gas InP

Broadband terahertz radiation from a biased two-dimensional electron gas in an AlGaN/GaN heterostructure

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Journal of Semiconductors 2015年第10期36卷 55-59页

作者：郑中信孙建东周宇张志鹏秦华 Key Laboratory of Nanodevices and Applications Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of Sciences University of Chinese Academy of Sciences

The broadband terahertz （THz） emission from drifting two-dimensional electron gas （2DEG） in an AI- GaN/GaN heterostructure at 6 K is reported. The devices are designed as THz plasmon emitters according to the Smith-Purcell effect and the ＇shallow water＇ plasma instability mechanism in 2DEG. Plasmon excitation is excluded since no signature of electron-density dependent plasmon mode is observed. Instead, the observed THz emission is found to come from the heated lattice and/or the hot electrons. Simulated emission spectra of hot electrons taking into account the THz absorption in air and Fabry-Pérot interference agree well with the experiment. It is confirmed that a blackbody-like THz emission will inevitably be encountered in similar devices driven by a strong in-plane electric field. A conclusion is drawn that a more elaborate device design is required to achieve efficient plasmon excitation and THz emission.

关键词： two-dimensional electron gas hot electron blackbody radiation plasmon Fabry-Pérot cavity

Formation of two-dimensional electron gas at AlGaN/GaN heterostructure and the derivation of its sheet density expression

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Chinese Physics B 2015年第6期24卷 516-520页

作者：何晓光赵德刚江德生 State Key Laboratory on Integrated Optoelectronics Institute of SemiconductorsChinese Academy of Sciences

Models for calculating the sheet densities of two-dimensional electron gas （2DEG） induced by spontaneous and piezoelectric polarization in A1GaN/GaN, A1GaN/A1N/GaN, and GaN/A1GaN/GaN heterostructures are provided. The detailed derivation process of the expression of 2DEG sheet density is given. A longstanding confusion in a very widely cited formula is pointed out and its correct expression is analyzed in detail.

关键词： high electron mobility transistors GaN two-dimensional electron gas polarization effect

Influence of a two-dimensional electron gas on current-voltage characteristics of Al_(0.3)Ga_(0.7) N/GaN high electron mobility transistors

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Chinese Physics B 2012年第6期21卷 443-447页

作者：冀东刘冰吕燕伍邹杪范博龄 School of Science Beijing Jiaotong University School of electronic and Information Engineering Beijing Jiaotong University

The J-V characteristics of AltGa1 tN/GaN high electron mobility transistors（HEMTs） are investigated and simulated using the self-consistent solution of the Schro dinger and Poisson equations for a two-dimensional electron gas（2DEG） in a triangular potential well with the Al mole fraction t = 0.3 as an example.Using a simple analytical model,the electronic drift velocity in a 2DEG channel is obtained.It is found that the current density through the 2DEG channel is on the order of 10^13 A/m^2 within a very narrow region（about 5 nm）.For a current density of 7 × 10^13 A/m62 passing through the 2DEG channel with a 2DEG density of above 1.2 × 10^17 m^-2 under a drain voltage Vds = 1.5 V at room temperature,the barrier thickness Lb should be more than 10 nm and the gate bias must be higher than 2 V.

关键词： two-dimensional electron gas high electron mobility transistor heterointerface nitridesemiconductor

Degradation mechanism of two-dimensional electron gas density in high Al-content AlGaN/GaN heterostructures

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Chinese Physics B 2009年第7期18卷 2998-3001页

作者：张进成郑鹏天张娟许志豪郝跃 Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University

This paper finds that the two-dimensional electron gas density in high Al-content A1GaN/GaN heterostructures exhibits an obvious time-dependent degradation after the epitaxial growth. The degradation mechanism was investigated in depth using Hall effect measurements,high resolution x-ray diffraction,scanning electron microscopy,x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy.The results reveal that the formation of surface oxide is the main reason for the degradation,and the surface oxidation always occurs within the surface hexagonal defects for high Al-content AlGaN/GaN heterostructures.

关键词： degradation mechanism two-dimensional electron gas AlGaN/GaN heterostructures,surface oxidation

Calculations of two dimensional electron gas distributions in AlGaN/GaN material system

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Chinese Physics B 2008年第1期17卷 290-295页

作者：郭宝增宫娜于富强 College of electronic and Informational Engineering Hebei University College of Physics Hebei Normal University

This paper presents calculating results of the two-dimensional electron gas （2DEG） distributions in AlGaN/GaN material system by solving the Schroedinger and Poisson equations self-consistently. Due to high 2DEG density in the AlGaN/GaN heterojunction interface, the exchange correlation potential should be considered among the potential energy item of Schroedinger equation. Analysis of the exchange correlation potential is given. The dependencies of the conduction band edge, 2DEG density on the Al mole fraction are presented. The polarization fields have strong influence on 2DEG density in the AlGaN/GaN heterojunction, so the dependency of the conduction band edge on the polarization is also given.

关键词： GaN heterojunction exchange-correlation potential two-dimensional electron gas

The low-temperature mobility of two-dimensional electron gas in AlGaN/GaN heterostructures

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Chinese Physics B 2008年第7期17卷 2689-2695页

作者：张金风毛维张进城郝跃 Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices Microelectronics InstituteXidian University

To reveal the internal physics of the low-temperature mobility of two-dimensional electron gas （2DEG） in Al- GaN/GaN heterostructures, we present a theoretical study of the strong dependence of 2DEG mobility on Al content and thickness of AlGaN barrier layer. The theoretical results are compared with one of the highest measured of 2DEG mobility reported for AlGaN/GaN heterostructures. The 2DEG mobility is modelled as a combined effect of the scat- tering mechanisms including acoustic deformation-potential, piezoelectric, ionized background donor, surface donor, dislocation, alloy disorder and interface roughness scattering. The analyses of the individual scattering processes show that the dominant scattering mechanisms are the alloy disorder scattering and the interface roughness scattering at low temperatures. The variation of 2DEG mobility with the barrier layer parameters results mainly from the change of 2DEG density and distribution. It is suggested that in AlGaN/GaN samples with a high Al content or a thick AlGaN layer, the interface roughness scattering may restrict the 2DEG mobility significantly, for the AlGaN/GaN interface roughness increases due to the stress accumulation in AlGaN layer.

关键词： two-dimensional electron gas mobility AlGaN/GaN heterostructures interface roughness

Photoluminescence Investigation of two-dimensional electron gas in an Undoped AlxGa1-xN／GaN Heterostructure

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Chinese Physics Letters 2005年第8期22卷 2096-2099页

作者：韩修训吴洁君李杰民丛光伟刘祥林朱勤生王占国 KeyLaboratoryofSemiconductorMaterialsScience InstituteofSemiconductorsChineseAcademyofSciencesPOBox912Beijing100083

Low-temperature photoluminescence measurement is performed on an undoped AlxGa1-xN/GaN heterostructure. Temperature-dependent Hall mobility confirms the formation of two-dimensional electron gas (2DEG) near the heterointerface. A weak photoluminescence (PL) peak with the energy of similar to 79meV lower than the free exciton (FE) emission of bulk GaN is related to the radiative recombination between electrons confined in the triangular well and the holes near the flat-band region of GaN. Its identification is supported by the solution of coupled one-dimensional Poisson and Schrodinger equations. When the temperature increases, the red shift of the 2DEG related emission peak is slower than that of the FE peak. The enhanced screening effect coming from the increasing 2DEG concentration and the varying electron distribution at two lowest subbands as a function of temperature account for such behaviour.

关键词： DISLOCATION SCATTERING CARRIER CONFINEMENT POLARIZATION TRANSISTORS Transistor Device Component Red shift photoluminescence Radiative recombination two-dimensional electron gas electron gas Polarization electron distribution gallium nitrate dislocation scattering Hall mobility

Magnetotransport properties of two-dimensional electron gas in AlGaN/AlN/GaN heterostructures

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Chinese Physics B 2011年第9期20卷 377-380页

作者：马晓华马平焦颖杨丽媛马骥刚贺强焦莎莎张进成郝跃 School of Technical Physics Xidian University Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University

Magnetotransport measurements are carried out on the A1GaN/A1N/GaN in an SiC heterostructure, which demon- strates the existence of the high-quality two-dimensional electron gas （2DGE） at the A1N/GaN interface. While the carrier concentration reaches 1.32×10^13 cm^-2 and stays relatively unchanged with the decreasing temperature, the mobility of the 2DEG increases to 1.21 × 10^4 cm2/（V.s） at 2 K. The Shubnikov-de Haas （SdH） oscillations are observed in a magnetic field as low as 2.5 T at 2 K. By the measurements and the analyses of the temperature-dependent SdH oscillations, the effective mass of the 2DEC is determined. The ratio of the transport lifetime to the quantum scattering time is 9 in our sample, indicating that small-angle scattering is predominant.

关键词： A1GaN/A1N/GaN/SiC heterostructures two-dimensional electron gas Shubnikov-deHaas oscillations magnetotransport properties