Planar Schottky gate modulated low turn-on voltage AlN/GaN/AlGaN/GaN Schottky barrier diode

Abstract

A kind of GaN-based double-channel Schottky barrier diode (DC-SBD) with AlN/GaN/AlGaN/GaN mixed heterostructures was proposed in this work. A step-like profile was fabricated at the anode region using wet etching and self-terminating etching technology. The planar Schottky contact was formed on the top of the AlGaN barrier layer. The turn-on voltage (VON) of the fabricated DC-SBD, which did not use a low work function metal as the anode metal, had been decreased to 0.41 V, and the reverse leakage current at room temperature could be as low as 0.11 μA/mm at −200 V simultaneously, which achieved the best trade-off between VON and reverse leakage current among reported values of DC-SBD. The process of the turn-on of the DC-SBD was investigated by Technology Computer-aided Design simulation. It turned out that the planar Schottky gate could modulate the sidewall Schottky barrier height and decrease the VON of the DC-SBD, which depended on the thickness of the lower barrier layer as well. Meanwhile, it cannot increase the reverse leakage current due to the expanded depletion region formed by the planar Schottky contact. The breakdown voltage reached 914 V when the anode–cathode length (LAC) is 8 μm and the power figure-of-merit reached 1.90 GW/cm2. It demonstrated that the anode design could accommodate both the VON and the reverse leakage current simultaneously.