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

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 (Q_eff) and increasing interface-trap density (D_it) as a function of PDA temperature. The highest oxide breakdown field demonstrated by 1000°C-annealed sample was correlated with Q_eff and D_it. A detailed explanation on this correlation as well as current transport mechanism in these oxides has been presented. [ABSTRACT FROM AUTHOR]