A new vertical GaN SBD employing in-situ metallic gallium ohmic contact

Abstract

We proposed and fabricated new vertical GaN Schottky barrier diodes (SBDs) employing in-situ metallic gallium (Ga) ohmic contacts which increase the forward current of a vertical GaN SBD considerably. Highly conductive metallic Ga was formed in-situ at the bottom of n+ GaN substrate due to a high thermal budget during n-epi layer growth so that the ohmic contact was well-formed due to the metallic Ga. The forward current density of the proposed device was 625 A/cm2 at 2 V while that of the conventional device was 300 A/cm2. We also employed the floating metal ring and field plate to achieve the high breakdown voltage. The breakdown voltage of the proposed and conventional device was 880 V and 850 V respectively.