Suppression of threshold voltage shift for normally-Off GaN MIS-HEMT without post deposition annealing

In this paper, we present a method of reducing threshold voltage shift for normally-off GaN MIS-HEMT by the optimization of dielectric deposition conditions. High-temperature deposition of Al2O3 insulator decreases the impurities in a dielectric film, leading to small C-V and I-V hysteresis under large positive gate voltage operation. Moreover, Al2O3 deposited at high temperature achieve high quality interface and bulk without post deposition annealing (PDA), preventing the degradation of electrodes and crystallization of insulator film. The fabricated device shows small C-V and I-V hysteresis, with a breakdown voltage of greater than 600 V.