Polarization induced doping and high-k passivation engineering on T-gate MOS-HEMT for improved RF/microwave performance

Abstract

High electron-mobility transistors (HEMTs) based on III-nitrides are well-known as ideal choices for high-power, radio-frequency applications. HEMTs, on the other hand, must deal with the critical issues of the large gate and buffer leakage currents, which unavoidably restrict device performance and reliability. Here, we use HfO2 as a gate dielectric to mimic an InAlN/AlN meta-oxidesemiconductor high electron mobility transistor (MOS-HEMT) that can enhance the interfacial and transport characteristics and reduce the gate leakage current. Furthermore, polarization-induced doping in the buffer region is also implemented, enhancing the two-dimensional electron gas confinement by bending the conduction band upwardly convex, effectively reducing the buffer leakage current, and enhancing the breakdown voltage (35 V). The implementation of the above two engineerings significantly enhances the gain maximum oscillation frequency (246 GHz) and cut-off frequency (156 GHz). The simulated results of the proposed device design show its applicability for high RF/microwave applications.