The effect of scattering mechanisms on the low field mobility in GaN/AlGaN heterostructures

The effect of all standard scattering mechanisms, including scattering by acoustic and optical phonons, background impurities and dislocation, on two-dimensional electron gas (2DEG) transport in GaN/AlGaN heterostructures is presented. In order to compare the experimental results with the theory, the simple analytical formulas have been used for a 2DEG confined in a triangular well. At high temperatures electron mobility is ultimately limited by optical phonon scattering. At intermediate temperatures acoustic deformation potential and piezoelectric scattering are the dominant scattering mechanisms. The dislocation scattering prevails at low temperatures and the 2DEG mobility is affected strongly by high density of dislocations. We also investigate the transport to quantum lifetime ratios due to charge dislocations. It is found that ratio is larger for dislocation scattering than for impurity scattering. (C) 2004 Elsevier B.V. All rights reserved.