High-performance normally off p-GaN gate high-electron-mobility transistor with In0.17Al0.83N barrier layer design

This paper proposes a novel normally-off p-GaN gate InAlN/GaN HEMT to replace p-GaN gate AlGaN/GaN HEMT for improving the device stability, enhancing saturation current, reducing the on-state resistance, improving the cut off frequency and decreasing the subthreshold swing. Due to the higher two-dimensional electron gas induced by the polarization, the on-state resistance for p-GaN gate InAlN HEMT can be lowered by 23% while the on-state current can be enhanced by 161% comparing with the common p-GaN gate AlGaN HEMT at Vgs = 5 V. The cut off frequency of InAlN HEMT is 11.5 GHz, which is 39% higher than that of AlGaN HEMT. While the low breakdown voltage (BV) of InAlN HEMT restricts the device performance and power application. The thickness and permittivity of the passivation layer are found to influence the BV of the device significantly, due to the alleviation of peak electric field at the drain-side gate edge, leading to a much smoother distribution of electric field in the channel. A proposed structure with TiO2 passivation layer exhibits a breakdown of 1028 V, showing 25% increase in breakdown voltage compared to the TiO2 passivation layer AlGaN HEMT. These simulation results revealed that the p-GaN gate InAlN/GaN HEMT is a reliable candidate in power application.