Interfacial bonding distribution and energy band structure of (Gd2O3)1 − x(SiO2)x (x = 0.5)/GaAs (0 0 1) system

Abstract

A (Gd2O3)1 − x(SiO2)x (x = 0.5) gate dielectric film was deposited on an n-GaAs (001) substrate at various substrate temperatures. Bonding distribution of interfacial Ga and As was characterized by comparing the 3d and 3p photoelectron lines. Surface passivation using (NH4)2S was employed to preserve a stable interface. Interfacial GaAs oxide was not formed after the deposition, since bonding transition from As-S to Ga-S bonds provides thermal stability and protective effect against oxidation. While, without the passivation, interfacial GaAs-oxides were continuously grown as the substrate temperature was increased. The energy band gap of (Gd2O3)0.5(SiO2)0.5 was defined as 6.8eV using energy loss spectra of O 1s photoelectrons. The valence band maximum energy (EVBM) of (Gd2O3)0.5(SiO2)0.5 was determined to be 3.7eV. By arrangement of the measured energy bandgap and EVBM, the energy band structure of (Gd2O3)0.5(SiO2)0.5/GaAs system was demonstrated and an enhanced conduction band offset was observed.