Physical Review B 72, 245303 (2005)

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Roughness-induced mechanisms for electron scattering in wurtzite group-III-nitride heterostructures
Roughness-induced mechanisms for electron scattering in wurtzite group-III-nitride heterostructures
 Tạp chí Physical Review B 2005 2 December 2005; 72 (24):245303
 Tác giả   Doan Nhat Quanga, Nguyen Huyen Tungb, Vu Ngoc Tuocb, Nguyen Viet Minhb and Pham Nam Phongb
 Nơi thực hiện   a Center for Theoretical Physics, Vietnamese Academy of Science and Technology, P.O. Box 429, Boho, Hanoi 10000, Vietnam

bInstitute of Engineering Physics, Hanoi University of Technology, 1 Dai Co Viet Road, Hanoi, Vietnam

 Từ khóa   piezoelectric, strain relaxation, heterostructures, wurtzite structure
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Abstract[sửa]

We present a theory of the low-temperature mobility of the two-dimensional electron gas (2DEG) in wurtzite group-III-nitride heterostructures, e.g., AlGaN/GaN, taking adequate account of the roughness-induced scattering mechanisms and the effect due to sheet polarization charges. The squeeze of the electron distribution in the quantum well by positive piezoelectric and spontaneous polarization-induced charges on the interface is calculated in an analytic form. Thus, we obtained simple expressions describing the squeeze-related enhancement of the 2DEG screening and the unscreened potentials for different scattering sources. Altogether, their screened potentials may be strongly enhanced, so that the 2DEG mobility may be remarkably reduced by sheet polarization charges. Moreover, we proved that the roughness-induced piezoelectric charges and the roughness-induced deformation potential exhibit new important scattering mechanisms governing the 2DEG transport in wurtzite III-nitride heterostructures. The partial 2DEG mobilities limited by them may be of the order of or less than 10^{3}cm^{2}/Vs. Our theory turns out to be successful in the quantitative explanation of recent experimental data about the high-density 2DEG mobility, e.g., its nonmonotonic dependence on carrier density and its enhancement in the double heterostructure, which have not been understood starting merely from the conventional scattering mechanisms.