Quantitative depth profiling of oxygen in homoepitaxial SrTiO3 films

We have investigated the quantitative depth profiling of oxygen content in SrTiO3 substrates and SrTiO3 films on SrTiO3 substrates using 16O(α,α)16O 3.045 MeV resonant backscattering spectrometry. SrTiO3 films were evaporated onto SrTiO3 substrates by molecular beam epitaxy methods with an introduction of reactive O3 gas. 16O(α,α)16O resonant backscattering was corrected and an absolute content of oxygen concentration could be accurately estimated as well as other metallic elements. For SrTiO3 substrates, one kind of SrTiO3 substrate fabricated at one company had a different composition from a chemical stoichiometry (namely, Sr:Ti:O=1:1:3) and indicated a remarkable deficiency of Sr and oxygen component, while another kind of SrTiO3 substrate fabricated at another company had the chemical stoichiometric composition. SrTiO3 film compositions were strongly affected by the compositions of SrTiO3 substrates, and nearly constant depth profilings were obtained from film surfaces to substrate surfaces in spite o...