720-V/0.35-m Ω · cm2Fully Vertical GaN-on-Si Power Diodes by Selective Removal of Si Substrates and Buffer Layers

This letter demonstrates a novel technology to fabricate fully vertical GaN-on-Si power diodes with state-of-the-art performance. Si substrate and buffer layers were selectively removed and the bottom cathode was formed in the backside trenches extending to an n+-GaN layer. A specific differential ON-resistance of 0.35-0.4 mΩ·cm2(normalized to the total device area) and a breakdown voltage of 720 V were demonstrated in this novel fully-vertical GaN-on-Si p-n diode, rendering a Baliga's figure of merit over 1.5 GW/cm2. These results set a new record performance in all vertical GaN power diodes on foreign substrates, and demonstrate the feasibility of making fully vertical GaN-on-Si power diodes and transistors by selective removal of Si substrates and buffer layers.