Both the AES depth profile and TEM images for the annealed contacts show that Ni performed poorly as a diffusion barrier. It could not prevent inward diffusion of the top Au layer into the Ta/Ti bilayer, and also into the n-GaN epilayer underneath it, during rapid thermal annealing (RTA). As a result, thermal alloying at elevated temperatures led to the formation of several Au-based solid solutions embedded on the GaN epilayer and on other parts of the microstructure. Thus, it was revealed that, upon RTA, the n-GaN/Ta/Ti/Ni/Au system yielded the alloy in the vicinity of the metal/n-GaN interface.
ASJC Scopus subject areas
- Physics and Astronomy(all)