V/Al-based ohmic contact formation to n-GaN using low temperature annealing

Abstract

We describe the dependence of annealing temperature on the ohmic contact resistance for n-type GaN layers having ohmic metal stacks of V/Al/Mo/Au and Ti/Al/Mo/Au. Measurement results indicated that the contact resistance for V/Al/Mo/Au with a doping level of 2×1018 cm-3 was 0.35 Ωmm after annealing at 600 °C, while that for Ti/Al/Mo/Au did not show good ohmic behaviors after annealing below 650 °C. These results indicate that V/Al/Mo/Au is a good alternative to Ti/Al/Mo/Au and is suited for low-temperature annealing. Interdiffusion of metals during annealing studied by Auger electron spectroscopy will be also discussed.