The low-temperature mobility of two-dimensional electron gas in AlGaN/GaN heterostructures |
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Authors: | Zhang Jin-Feng Mao Wei Zhang Jin-Cheng and Hao Yue |
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Institution: | Key Laboratory of Ministry of Education for Wide Band-Gap
Semiconductor Materials and Devices, Microelectronics Institute,
Xidian University, Xi'an 710071, China |
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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. |
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Keywords: | two-dimensional electron gas mobility AlGaN/GaN heterostructures interface roughness |
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