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 $1–9×1012cm−2$ 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.