High-voltage GaN SBD on Si substrate by suppressing metal spikes

Abstract

We have successfully fabricated high-voltage GaN Schottky barrier diodes (SBDs) on Si substrate by suppressing metal spikes under ohmic contacts. The breakdown voltage of GaN SBDs is 450 V with superior device-to-deice uniformity. Metal spikes are suppressed by low-temperature annealing at 700 °C. The low contact resistance of 0.6 ohm-mm is also achieved due to ohmic contacts on the doped GaN. The diffusion of Ti/Al/Mo/Au into GaN is analyzed by Auger electron spectroscopy and scanning electron microscope. The depth and the number of metal spikes are proportional to the annealing temperature of ohmic contacts. Metal spikes in GaN power devices should be suppressed for the low power loss and the high breakdown voltage.