Potential study of the enhanced breakdown voltage GaN MISFET based on partial AlN buried layer

Abstract

In this paper, a new structure for GaN MISFET is proposed to enhance its breakdown voltage. The proposed structure uses an Aluminum nitride (AlN) buried layer embedded inside the GaN buffer layer. The AlN buried layer is employed to reduce the peak electric field strength near the gate, introducing a high electric field peak in the GaN buffer layer. The GaN/AlN heterojunction formed by the GaN buffer layer and the AlN buried layer introduces two electric field peaks, and enhances the uniformity of the electric field distribution in the GaN buffer layer. Simulation results of the proposed structure show that the breakdown voltage is enhanced by 78% when compared to the conventional GaN MISFET. Moreover, the specific on-resistance (Ron,sp) is improved since the AlN buried layer provides two-dimensional electron gases in the GaN buffer which can cause the charge to increase.