Band Configuration of SiO₂/m-Plane ZnO Heterointerface Correlated with Electrical Properties of Al/SiO₂/ZnO Structures

Abstract

SiO 2 films have been deposited on m-plane ZnO(1 100) substrates by atomic layer deposition method at 200 C and the interface has been investigated. Band structures of amorphous SiO 2 /m-plane ZnO(1 100) heterointerface have been characterized by X-ray photoelectron spectroscopy, showing type I band configuration with valence and conduction band offsets of 1:7 AE 0:2 and 3:6 AE 0:2 eV, respectively. Capacitance-voltage (C-V ) measurements of Al/SiO 2 /m-plane ZnO(1 100) have been performed. When gate bias was swept from positive to negative, a ledge appeared in the C-V curve of the Al/SiO 2 /m-plane ZnO structure, which is probably due to the emission of electrons trapped at the near-midgap deep levels. However, it is found that the surface treatment for ZnO using HCl yielding automatically flat stepped and terraced surface improves the C-V curve without the ledge. #