Dislocation scattering effect on two-dimensional electron gas transport in GaN/AlGaN modulation-doped heterostructures
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We present the effect of all standard scattering mechanisms, including scattering by acoustic and optical phonons, remote and background impurities and dislocation, on two-dimensional electron gas (2DEG) transport in AlGaN/GaN modulation doped-heterostructures. The most important scattering mechanisms limiting electron transport are identified. From the calculated dependence of mobility on temperature, it is clear that dislocation scattering dominates the low-temperature mobility of two-dimensional electrons in GaN/AlGaN structures with a high electron density n(s) > 10(12) cm(-2) and the maximum 2DEG mobilities will be in the 10(2)-10(4) cm(2)/V s range for dislocation density of 4 x 10(10) cm(-2) and carrier densities in the 1 x 10(12) -2 x 10(13) cm(-2). This theoretical calculations fairly agree with the same mobility value obtained by the experimental for 4 x 10(10) cm(-2) dislocation density. The results are compared to the transport to quantum lifetime ratios due to charge dislocations. We find that the ratio is larger for dislocation scattering than for impurity scattering.