Transport-to-quantum lifetime ratios in AlGaN/GaN heterostructures

We have calculated ratios of the transport-to-quantum lifetimes τt/τq of the two-dimensional electron gas in AlGaN/GaN heterostructures at low temperatures. In contrast to conventional interpretations, we show that large values of this ratio do not necessarily indicate that long-range scattering mechanisms such as Coulomb scattering are the dominant carrier scattering mechanisms and that large ratios (>20) can be obtained even when short-range scattering mechanisms are dominant.