Designing Beveled Edge Termination in GaN Vertical p-i-n Diode-Bevel Angle, Doping, and Passivation

Abstract

A series of electric field profile simulations in gallium nitride (GaN) p-i-n vertical diodes with negative bevel termination is carried out to optimize the bevel design. The bevel angles are varied from 90° to 0.1° with reasonably small increments to study the impact of the bevel angle on the electric field profile. The doping densities are also varied to study a more generalized trend; a new parameter defined as transition angle $\theta _{{\text {t}}}$ is proposed to characterize the effectivity of a beveled edge termination. Considering the potential dry etch damage on the bevel side-wall during device fabrication, the fixed surface charge from the dangling bonds and commonly used dielectric passivation are also added separately to investigate their influence. This article presents a comprehensive simulation study of GaN p-i-n diode with negative beveled edge termination, making it a useful guide for designing a simple and effective beveled edge termination, which eventually helps to enable the routine avalanche in GaN p-i-n diodes.