Atomic and electronic structures of SrTiO${}_{3}$/GaAs heterointerfaces: An 80-kV atomic-resolution electron energy-loss spectroscopy study

Atomic and electronic structures of SrTiO $_{3}$ /GaAs heterointerfaces: An 80-kV atomic-resolution electron energy-loss spectroscopy study

Q. Qiao, R. F. Klie, S. Öğüt, and J. C. Idrobo

Phys. Rev. B 85, 165406 – Published 3 April 2012

Abstract

We have examined the atomic and electronic structures of epitaxially grown, ultrathin SrTiO $_{3}$ (100) films on GaAs (001) using 80-kV aberration-corrected atomic-resolution $Z$ -contrast imaging and electron energy-loss spectroscopy (EELS) to develop a fundamental understanding of the interfacial structure-property relationships. We find that the interface is atomically abrupt and no surface reconstruction of the GaAs (001) surface is observed. Using atomic-column resolved EELS, we examine the oxygen vacancy and Ti concentrations in the SrTiO $_{3}$ film and across the heterointerface. We show that Ti diffuses into the first few monolayers of GaAs. Using a combination of EELS and first-principles calculations, we present evidence for the formation of As oxides at the interface depending on the thin-film growth conditions. These findings are used to explain the differences in the transport behavior of the films.