Study on Gallium Nitride-Based Metal–Oxide–Semiconductor Capacitors With RF Magnetron Sputtered $hbox{Y}_{2}hbox{O}_{3}$ Gate

摘要

Effects of postdeposition annealing (PDA) temperatures (200 $^{circ} hbox{C}$–1000 $^{circ}hbox{C}$) in argon ambient on radio-frequency magnetron sputtered $hbox{Y}_{2}hbox{O}_{3}$ film on n-type GaN substrate were studied. As-deposited $hbox{Y}_{2} hbox{O}_{3}$ film was amorphous as no $hbox{Y}_{2}hbox{O}_{3}$ phase was detected by X-ray diffraction. A transformation of the amorphous to polycrystalline phase happened when PDA $(geqhbox{200} ^{circ}hbox{C})$ was carried out. The detection of $betahbox{-}hbox{Ga}_{2}hbox{O}_{3}$ phase for samples annealed beyond 400 $^{circ}hbox{C}$ denoted the formation of interfacial layer (IL) consisting of an $ hbox{Y}_{2}hbox{O}_{3}$ and $betahbox{-}hbox{Ga}_{2} hbox{O}_{3}$ mixture. The formation of IL was revealed by cross-sectional energy-filtered transmission electron microscopy images. Metal–oxide–semiconductor characteristics of $hbox{Y}_{2}hbox{O}_{3}/hbox{GaN}$ structure annealed at different temperatures were correlated with structural and surface morphology analysis. The 400- $^{circ}hbox{C}$-annealed sample demonstrated the highest electric breakdown field ($sim$10.7 MV/cm) due to the attainment of the lowest effective oxide charge, semiconductor–oxide interface-trap density, and total interface-trap density.