Investigation of High-k Dielectric Passivation Effects on DC Performance of AlN/β-Ga2O3 HEMTs

In this article, the effect of different high-k dielectric passivation layers on the DC characteristics of AlN/β-Ga2O3 based High Electron Mobility Transistor (HEMT) has been investigated. Three high-k dielectric materials namely Si3N4, Al2O3 and HfO2 are considered for this investigation. The proposed device with different high-k dielectrics are investigated for a number of DC characteristics, including maximum drain current, peak transconductance, ION/IOFF ratio, sub-threshold swing (SS), total gate capacitance, and maximum output transconductance using TCAD numerical simulation. Enhanced DC performance in terms of maximum drain current density of 0.8 A/mm, peak transconductance of 0.56 S/mm, overall gate capacitance of 3.4 pF/mm and sub-threshold swing of 36 mV/dec is exhibited by AlN/β-Ga2O3 HEMT for HfO2 passivation layer as compared to its counterparts. However, ION/IOFF ratio is found to be highest, when HfO2 is used as a high-k dielectric material which corresponds to the high 2-dimensional electron gas (2DEG) carrier density. The obtained results indicate that either HfO2 or Al2O3 can be the choice of passivation layer in AlN/β-Ga2O3 HEMT.