Design and Fabrication of Low-Leakage Vertical GaN TMBS Rectifier with Low Forward Voltage Drop

In this work, the vertical GaN trench MIS barrier Schottky (TMBS) rectifier was developed to reduce the leakage current density of the Schottky barrier diode. The vertical GaN TMBS rectifier was fabricated with self-aligned insulator opening process, in order to eliminate the gap between trench and Schottky edge (L
TS
). The L
TS
is induced by the mask-aligned insulator opening process, which would result in the peak electric field at the edge of Schottky contact on the mesa, leading to increased reverse leakage current. This work studies the influence of the TMBS structure on the device's performance. As mesa width narrows, the reverse leakage current density decreases and the breakdown voltage increases, due to the suppressed electric field at the Schottky interface and at the corner of the trench bottom. The vertical GaN TMBS rectifier exhibits the breakdown voltage of ~810 V and the leakage current density of ~10-
⁶
A/cm
²
. Furthermore, the forward conduction performance can be improved with hexagonal cell in contrast to the stripe cell, showing the moderate forward voltage drop of ~1 V. Besides, the high-temperature performances (up to 200°C) are also presented. These results show that the vertical GaN TMBS diode have great potential for the high-power-density and high-efficiency power electronic applications.