5 kV multi-channel AlGaN/GaN power schottky barrier diodes with junction-fin-anode

Abstract

This work demonstrates multi-kilovolt AlGaN/GaN Schottky barrier diodes (SBDs) on a 4-inch, five-channel, low-cost GaN-on-sapphire wafer. Our device highlights a new 3-D anode architecture, in which the p-n junction wraps around the multi-2DEG-channel fins. This junction-fin structure differs from all existing tri-anode and tri-gate structures, which employ a Schottky or a metal-insulator-semiconductor (MIS) stack at the fin sidewalls. Our junction-fin structure is realized with regrown p-GaN on the top of the fin and p-type NiOx at the fin sidewalls. Thanks to the strong charge depletion, this structure allows an over 10-fold reduction in device leakage current. The top p-GaN further extends towards the cathode, which shields the fin-anode region from the high electric field. Our SBDs show a breakdown voltage (BV) up to 5.2 kV with a leakage current of 1.4 μΑ/mm at 90% BV, as well as a specific on-resistance (Ron) of 13.5 mQ•cm2, rending a Baliga's figure of merit (FOM) of 2 GW/cm2, which exceeds the SiC 1-D unipolar limit and is among the highest in all multi-kilovolt power SBDs. In addition, large-area multi-channel AlGaN/GaN SBDs are demonstrated for the first time, with a 1.5 A current, a 4.8 kV BV with ~μΑ leakage current, and a 13 nC total charge. These results show the great potential of AlGaN/GaN multi-channel devices for medium- and high-voltage power applications.