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We report observations of crystal defect induced modifications in the laser-excited Er3+ photoluminescence spectra of single-crystal Er2O3 thin films. These include marked enhancement of transition intensities known to be weak or nonexistent in as-grown samples. In this Letter, we examine the temperature and defect density dependence of the measurements and suggest photophysical processes that may account for these unexpected results. 

Dry oxidation of Si (001) beneath a thin epitaxial SrTiO3 layer has been studied using furnace annealing in flowing oxygen. A 10-nm layer of SrTiO3 is epitaxially grown on Si with no SiO2 interlayer. For such a structure, an annealing temperature of 800 °C was found to be the limiting temperature to prevent silicate formation and disruption of the interface structure. The effect of annealing time on the thickness of the SiO2 layer was investigated. In situ x-ray photoelectron spectroscopy and reflection-high-energy electron diffraction were used to ensure that the quality of SrTiO3 is unchanged after the annealing process. The experimental annealing data are compared with a theoretical oxygen diffusion model based on that of Deal, Grove, and Massoud. The model fits the experimental data well, indicating that oxygen diffusion through the SrTiO3 layer is not the limiting factor. One can therefore readily control the thickness of the SiO2 interlayer by simply controlling the annealing time in flowing oxygen.