中国物理B ›› 2008, Vol. 17 ›› Issue (7): 2689-2695.doi: 10.1088/1674-1056/17/7/055

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

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

张金风, 毛维, 张进城, 郝跃   

  1. Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Microelectronics Institute, Xidian University, Xi'an 710071, China
  • 收稿日期:2008-02-20 修回日期:2008-03-21 出版日期:2008-07-09 发布日期:2008-07-09
  • 基金资助:
    Project supported by the Key Program of the National Natural Science Foundation of China (Grant No 60736033), and Xi'an Applied Materials Innovation Fund of China (Grant No XA-AM-200703), and the Open Fund of Key Laboratory of Wide Bandgap Semiconductors Material and Devices, Ministry of Education, China.

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

Zhang Jin-Feng(张金风), Mao Wei(毛维), Zhang Jin-Cheng(张进城), and Hao Yue(郝跃)   

  1. Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Microelectronics Institute, Xidian University, Xi'an 710071, China
  • Received:2008-02-20 Revised:2008-03-21 Online:2008-07-09 Published:2008-07-09
  • Supported by:
    Project supported by the Key Program of the National Natural Science Foundation of China (Grant No 60736033), and Xi'an Applied Materials Innovation Fund of China (Grant No XA-AM-200703), and the Open Fund of Key Laboratory of Wide Bandgap Semiconductors Material and Devices, Ministry of Education, China.

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摘要： To reveal the internal physics of the low-temperature mobility of two-dimensional electron gas (2DEG) in AlGaN/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 scattering 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.

Abstract: To reveal the internal physics of the low-temperature mobility of two-dimensional electron gas (2DEG) in AlGaN/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 scattering 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.

Key words: two-dimensional electron gas, mobility, AlGaN/GaN heterostructures, interface roughness

中图分类号:  (III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions)

  • 73.40.Kp
61.72.Hh (Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)) 68.35.Ct (Interface structure and roughness) 72.20.Fr (Low-field transport and mobility; piezoresistance) 73.20.At (Surface states, band structure, electron density of states)