Design and simulation of high breakdown voltage AlGaN/GaN HEMTs with a charged passivation layer for microwave power applications

Abstract

A novel high breakdown voltage AlGaN/GaN high electron mobility transistor with a charged passivation layer (CPL-HEMT) is proposed. The electrons in the channel are depleted by the negative charges in the passivation layer. The electric field distribution in the channel is modulated and becomes more uniform. Hence, an enhancement of breakdown voltage can be achieved. Compared to the conventional field-plate structure, the charged passivation layer structure introduces little parasitic capacitance. Numerical simulation demonstrates a breakdown voltage of 1125 V and an on-state resistance of \(0.48\,\hbox {m}\Omega \,\hbox {cm}^{2}\) with a gate-drain spacing of \(5\,\upmu \hbox {m}\) for the proposed device. The breakdown voltage of the CPL-HEMT increases by 120% compared to that of a conventional GaN-based HEMT, and the average breakdown electric field reaches as high as \(225\,\hbox {V}/\upmu \hbox {m}\).