Effect of HfO₂and Al₂O₃ high -k dielectrics double layer thickness on the breakdown voltage of enhancement mode of iii-v metal insulator semiconductor-high electron mobility transistor

Abstract

Dependence of Breakdown voltage (Vbr) on oxide thickness (TCH) for GaN-based Metal–Insulator Semiconductor High-Electron-Mobility Transistors (MIS-HEMTs) using HfO₃ and Al₂O₃ as gate dielectric is studied in detail. Different (III-V) heterostructures (AlGaN/GaN and AlInN/GaN) with different dielectrics passivation layers were used and compared with HfAlOx double layer thickness for the simulation of these MIS devices. Interestingly, for all the sets of devices, anincrease in Vbr was observed initially with Al₂O₃, followed by another positive shift with HfAlOxof the same. A maximum of Vbr1500V was achieved. A comprehensive analytical model has been proposed to explain the variation of Vbr withAl₂O₂dielectrics and HfAlOx has been shown to match the experimental data for MIS-HEMTs fabricated on different heterostructures and with different values dielectrics. This model allows the extraction of different charge components in the oxide or at oxide/III-V interface. Normally OFF AlGaN/GaN MIS-HEMTs have been demonstrated with the optimized TCH of HfO2 and Al₂O₃. Index Terms—HfO₂, Al₂O₃, AlGaN/GaN, MIS-HEMT, oxide thickness, threshold voltage