Enhancement of positive bevel β-Ga2O3 trench MOS barrier Schottky diode by post-etching treatment

Abstract

A β-Ga₂O₃ trench MOS barrier Schottky (TMBS) diode with a novel terminal structure of positive bevel mesa and arc bottom corners has been designed and realized in this work. O₂ plasma, hydrogen fluoride (HF), and tetramethylammonium hydroxide (TMAH) are used for post-etching treatment of devices, respectively. Measurement results shows that the specific on-resistance of the three devices are nearly with the same value of 2.60 mΩ·cm². The breakdown voltage of the devices with O₂ plasma, HF, and TMAH treatments are 1280 V, 1440 V, and 1800 V, respectively. Moreover, it is worth nothing that devices treated with O₂ plasma have a lower reverse leakage. In addition, the breakdown location of the device is determined to be at the β-Ga₂O₃ interface under the edge of the field plate by combining simulation and capacitance breakdown testing. AFM and XPS are used to analyze the surface properties of β-Ga₂O₃ after post-etching treatments. The results show that the TMAH treatments have the most significant effect on reducing surface roughness, and the O₂ plasma treatments is the most effective in decreasing oxygen vacancies.