Hetero-epitaxy of perovskite oxides on GaAs(001) by molecular beam epitaxy

Hetero-epitaxy of single-crystal perovskite SrTiO3 on GaAs(001) was achieved using molecular beam epitaxy. The growth was accomplished by deposition of a submonolayer of titanium on GaAs(001), followed by the co-deposition of strontium and titanium initiated at a low-temperature, low-oxygen-pressure condition. X-ray photoelectron spectroscopy showed that the Ti prelayer reacted with As and formed TiAs-like species on the As terminated GaAs(001) surface. Reflection-high-energy-electron diffraction showed that SrTiO3 grew coherently on the GaAs(001) at early stage of growth. This coherent behavior began to degrade when SrTiO3 thickness exceeded 20A. Cross-sectional transmission electron microscopy revealed an abrupt interface between SrTiO3 and GaAs and good crystallinity of the SrTiO3 film. An epitaxial relationship between SrTiO3 and GaAs was further confirmed by x-ray diffraction. The success of growth of SrTiO3 on GaAs paves the way for integration of various functional perovskite oxides with GaAs.