Atomic structure of epitaxial SrTiO_3-GaAs(001) heterojunctions

摘要

We have examined the atomic and electronic structures of epitaxial SrTiO_3 thin films on GaAs (001) deposited under different growth conditions in order to understand the interfacial structure-property relationships. High-resolution Z-contrast images show an atomically sharp heterointerface with SrTiO_3[110] in perfect registry with GaAs [100] and the interfacial structure remains unchanged if a submonolayer of Ti was deposited prior to the SrTiO_3 film growth. X-ray photoelectron spectroscopy shows that the Fermi level was pinned during the initial stage of growth when a submonolayer of Ti was deposited on As-terminated GaAs(001); subsequent SrTiO_3 growth alleviated this pinning. These results indicate a self-driven interfacial atomic structure formation, independent of the initial stage of growth.