Influence of the Groove Depth on the Electrical Characteristics of the Vertical GaN Trench MOSFETs

In this work, the groove depth of the vertical GaN trench MOSFETs have been investigated by TCAD simulation. The groove depth is found to have a crucial influence on the specific on-resistance and breakdown voltage. A deep enough groove is required to annihilate the build-in barrier between the p-body and the n-drift region close to the sidewall of the groove, in order to reduce the specific on-resistance. On the other hand, an increased groove depth will also cause electrical field peak and hence degrade the breakdown voltage. Therefore, there is a trade-off between the specific on-resistance and breakdown voltage, and optimization is required. This study has provided a quantitative analysis on the optimization scheme.