Effects of thermal annealing on Ni/Ta/n-GaN Schottky diodes

The thermal effects of Ni/Ta/n-GaN Schottky diodes have been investigated f or the first time using current-voltage, X-ray photoemission spectroscopy a nd Auger electron spectroscopy (AES) methods. Their barrier height is found to increase monotonously with increasing annealing temperature up to 800 d egreesC. Preliminary results indicate that when a Th intermediate layer is added into the Ni/GaN diodes, it can prevent the metal-semiconductor interd iffusion and Ni accumulation adjacent to GaN substrate to a large extent so that a more thermally stable device can be obtained.