Direct measurement of interfacial structure in epitaxial Gd2O3 on GaAs (001) using scanning tunneling microscopy

The epitaxial growth of Gd"2O"3 on GaAs (001) has given a low interfacial density of states, resulting in the demonstration of the first inversion-channel GaAs metal-oxide-semiconductor field-effect transistor. Motivated by the significance of this discovery, in this work, cross-sectional scanning tunneling microscopy is employed herein to obtain precise structural and electronic information on these epitaxial films and interfaces. At the interface, the interfacial stacking of Gd"2O"3 films is directly correlated with the stacking sequence of the substrate GaAs. Additionally, from the local electronic states across the gate oxides, the spatial extent of the GaAs wavefunctions into the oxide dielectric may suggest a minimum Gd"2O"3 thickness to be of bulk properties.