Breakdown Voltage Enhancement of GaN diodes with High-k Dielectric

Gallium nitride (GaN) has the great potential for high-power devices due to its wide bandgap and high breakdown field. In particular for high-power GaN pn diodes, critical field is noticed at the p-n interface and electrode edges at a high reverse bias. Therefore, to achieve high breakdown voltage, electric field at the edges need to be decreased. Edge termination techniques such as guard rings and field plate help with field management, the critical electric field is still located at the edge of the electrode. To decrease the effects of high electric field and also to reduce the surface leakage current, addition of passivation layer is generally used. In such device structures, the electric field in the passivation layer decreases abruptly. To mitigate the field crowding effect, in this work, we implemented a thin high-k dielectric layer for breakdown voltage enhancement. We show significant breakdown voltage improvement on GaN p-n diodes with high-k dielectric (Barium titanate, BTO, ε~ 180)/spin-on-glass (SOG) passivation layers in comparison with devices with only low-k (3.9) SOG passivation layer.