Over 10 kV vertical GaN p-n junction diodes with high-K/low-K compound dielectric structure
In this letter, a vertical GaN p-n junction diode with high-K/low-K compound dielectric structure (GaN CD-VGD) is proposed. The high-K/low-K compound dielectric structure consists of a layer of high dielectric constant and multilayer dielectric layers which have a lower dielectric constant, and these compound dielectric layers formed along the current flow direction. Compared with a conventional p-n diode, the edge electric field will be suppressed due to the effects of high-K passivation. And a new electric field peak will be introduced in the p-n diodes, because of a discontinuity of electrical field at the interface of high-K and low-K layer. Therefore the distribution of electric field in p-n diodes will become more uniform and an enhancement of breakdown voltage can be achieved. A best trade-off breakdown voltage (BV) and on-resistance (Ron) have been obtained by optimizing device parameters including dielectric layer situation, length and width. Numerical simulation demonstrate that GaN CD-VGD with a BV of 10650V and a Ron of 5.83 mΩ-cm2, resulting in a figure-of-merit (VB2/Ron) of 19 GW/cm2.