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Electron Mobility in Al x Ga 1 −x As Based Square‐Parabolic Double Quantum Well HEMT Structure − Effect of Asymmetric Doping Profile
Author(s) -
Sahoo Narayan,
Panda Ajit K.,
Sahu Trinath
Publication year - 2017
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201700221
Subject(s) - high electron mobility transistor , quantum well , condensed matter physics , resonance (particle physics) , doping , electron mobility , electron , scattering , chemistry , materials science , physics , atomic physics , optics , transistor , quantum mechanics , laser , voltage
We study the asymmetric doping dependence of electron mobility µ in an Al x Ga 1− x As based square‐parabolic double quantum well (SPDQW) high electron mobility transistor (HEMT) structure. We consider the square (parabolic) well and doping concentration N d1 ( N d2 ) in the barrier toward the substrate (surface) of the structure. Keeping N d1 fixed, variation of N d2 leads to the resonance of subband states of the individual wells at a N d2 > N d1 . The mobility is calculated as a function of N d2 by considering ionized impuritiy ( ii ‐), interface roughness ( ir ‐) and alloy disorder ( al ‐) scatterings. We show that near resonance of the subband states, the dip in µ arises due to the substantial change in the ir‐ and al ‐intersubband scattering rate matrix elements. The dip in μ is significant in SPDQW because of the sharp variations of subband wave functions between the wells due to the asymmetric potential profiles. Enhancement of the well width and central barrier width increases μ and sharpness of the dip in μ . Keeping N d2 constant and N d1 varying, the resonance occurs at N d1 < N d2 with similar nonlinearities in μ . Our results of µ can be utilized for the analysis of the performance of the HEMT devices.