Over 3000 cm2 V−1 s−1 room temperature two-dimensional electron gas mobility by annealing Ni/Al deposited on AlGaN/GaN heterostructures

Abstract

We investigated sheet electron density (ns) and electron mobility (μ) in AlGaN/GaN heterostructures deposited with Ni/Al by annealing in vacuum. We observed that both ns and μ at room temperature increased by annealing at 1020 K and the amount of increase depended on the Ni/Al stack thickness. We achieved a room temperature Hall electron mobility of 3050 cm2 V−1 s−1, which is the highest value ever reported for AlGaN/GaN heterostructures. The origin of ns increase was attributed to the additionally induced tensile strain in AlGaN layer, which was confirmed by Raman spectroscopy.