Effects of post-deposition annealing in O2 on threshold voltage of Al2O3/AlGaN/GaN MOS heterojunction field-effect transistors

Abstract

In this paper, we investigated the effects of the post-deposition annealing (PDA) on the threshold voltage (Vth) of AlGaN/GaN MOS heterojunction field-effect transistors with atomic-layer-deposited Al2O3 using H2O vapor or oxygen plasma as the oxidant. By PDA, the Vth shifts positively with the Vth variations depending on the oxidants. The capacitance–voltage measurements reveal that the Vth variation is attributed to the differences in the initial fixed charge density in the Al2O3 or/and the Al2O3/AlGaN for both oxidants.