Abstract
We investigated the structural evolution of the Ni/Au contact on GaN(0001) during annealing in N 2 , using in-situ x-ray diffraction, anomalous x-ray scattering, and high resolution electron microscopy. GaN decomposition occurred mostly along GaN dislocations at temperature higher than 500°C. The decomposed Ga diffused into Au and Ni substitutional positions, and the decomposed nitrogen reacted with Ni, forming Ni 4 N. Interestingly, Ni 4 N was grown epitaxially. The epitaxial relationship of the Ni 4 N, Au, and Ni was identified as M(111)//GaN(0002) and M[1-10]//GaN[1 1 -2 0] (M= Ni 4 N, Au, and Ni). At dislocation free regions, however, the atomically smooth interface remained intact up to 700°C. Remarkable improvement of device reliability is expected in the contact on dislocation free regions compared with the contact on dislocations.