Effect of Au distribution in NiO/Au film on the ohmic contact formation to p-type GaN

Abstract

The distribution of Au and NiO in NiO/Au ohmic contact on p-type GaN was investigated in this work. Au (5 nm) films were deposited on p-GaN substrates by magnetron sputtering. Some of the Au films were preheated in N 2 ambient to agglomerate into semi-connected structure (abbreviated by agg-Au); others were not preheated and remained the continuous (abbreviated by cont-Au). A NiO film (5 nm) was deposited on both types of samples, and all samples were subsequently annealed in N 2 ambient at the temperatures ranging from 100 to 500°C. The surface morphology, phases, and cross-sectional microstructure were investigated by scanning electron microscopy, glancing incident angle x-ray diffraction, and transmission electron microscopy. I-V measurement on the contacts indicates that only the 400°C

Effect of Ga dissolution in Au of Ni–Au system on ohmic contact formation to p-type GaN

“…This metallic Ni layer shall be transformed into NiO, which is considered as a barrier to resist the diffusion of Ga atoms from Au when the samples were annealed in O 2 ambient. According to the literature [18], NiO/Au contacting on p-GaN can lead to the intermixing of both layers after annealing. Therefore, an additional Au layer was sputtered on Ni/Au layers to stabilize the contact from intermixing of Ni/Au layers.…”