Quantum and transport lifetimes of two-dimensional electrons gas in AlGaN/GaN heterostructures

The transport and quantum lifetimes were respectively deduced from low-temperature mobility and Shubnikov-de Haas measurements as a function of carrier density in metal organic vapor phase epitaxy-grown AlGaN/GaN/sapphire heterostructures. We show experimentally that the lifetime ratio varies as a bell curve, qualitatively confirming a recent theoretical prediction. However the experimental ratio varied much less than was theoretically predicted: From 9 to 19 for carrier densities in 1-9x10(12) cm(-2) range. Moreover, we show the variation of quantum time with carrier density presents some discrepancy with the theoretical study. We also show that transport to quantum lifetime ratio cannot be used alone as a clear figure of merit from AlGaN/GaN heterojunctions. (c) 2005 Americian Institute of Physics.