Approaches to designing thermally stable Schottky contacts to n-GaN

The barrier heights of PdIn, Ni/Ga/Ni and Re Schottky contacts to n-GaN were investigated by current-voltage and capacitance-voltage measurements. Elemental Pd and Ni contacts were also investigated for comparison. In each case, the barrier heights were determined as a function of annealing temperature. It was shown that stoichiometric PdIn contacts were more stable than Pd-only contacts. Similarly, Ni/Ga/Ni diodes were found to be more stable than Ni diodes. Both the Ni/Ga/Ni contact and the elemental Re contact were stable on short-term annealing up to 700°C.