Mircrostructural investigation of oxidized Ni/Au ohmic contact to p-type GaN

摘要

The phase evolution of oxidized (10nm)Ni/(5nm)Au films on p-GaN was examined with a field emission gun transmission electron microscope in conjunction with composition analyses to explore the mechanism of formation of low resistance ohmic contact to p-GaN.The p-GaN/Ni/Au sample heat treated above 500 deg C in air was mainly composed of a mixture of crystalline NiO,Au and amorphous Ni-Ga-O phases.Small voids adjacent to the p-GaN film were also found.moreover,Nio partially contacts to p-GaN as well as Au islands and the amorphous Ni-Ga-O phases.The results suggest that the crystalline NiO and/or amorphous Ni-Ga-O phases may play a significant role in the formation of a low resistance ohmic contact to p-GaN.