Effects of N2O Postdeposition Annealing on Metal-Organic Decomposed CeO2 Gate Oxide Spin-Coated on GaN Substrate

Abstract

Effects of postdeposition annealing (PDA) in N2O ambient on metal-organic decomposed CeO2 films deposited on GaN substrate had been reported. The utilization of N2O gas during PDA had successfully suppressed the decomposition of GaN as revealed by x-ray diffraction (XRD). XRD had detected the presence of CeO2 and α-Ce2O3 phases, wherein the phase transformation of CeO2 to α-Ce2O3 led to the formation of β-Ga2O3 interfacial layer (IL). Formation of IL comprising of Ga–O and Ga–O–N compounds in CeO2/GaN system was verified by dark-field scanning transmission electron microscope image and energy dispersive x-ray line profile, respectively. The metal–oxide–semiconductor characteristics of CeO2/GaN structure showed a change of negative to positive effective oxide charge (Qeff) and increasing interface-trap density (Dit) as a function of PDA temperature. The highest oxide breakdown field demonstrated by 1000°C-annealed sample was correlated with Qeff and Dit. A detailed explanation on this correlation as well as current transport mechanism in these oxides has been presented.