Strain dependent electron drift velocity in Al 1– x In x N/AlN/GaN

We have measured the room‐temperature velocity–field characteristics in Al 1– x In x N/AlN/GaN strained structures ( x = 0.12, 0.15, 0.22) with two‐dimensional electron gas channels biased up to 200 kV/cm using nanosecond‐pulsed current–voltage technique. The drift velocity was estimated under assumptions of uniform electric field and no change in sheet electron density. No velocity saturation was observed. The lowest velocity was obtained for the heterostructure with an In content of x = 0.22. The experimental results are compared with those for lattice‐matched Al 1– x In x N/AlN/GaN, AlGaN/GaN, AlGaN/GaN/AlN/GaN, and silicon‐doped GaN. The conduction band profile, electron wave functions were calculated for the investigated nitride heterostructures through a self‐consistent solution of Schrödinger–Poisson equations. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)