Surface morphology of ultrathin hex-Pr2O3 films on Si(111)

Abstract

In this work, the morphology of the surface of hexagonal Pr2O3(0 0 0 1) films grown on Si(1 1 1) is studied by high-resolution low-energy electron diffraction combined with spot profile analysis. For this purpose, praseodymia films prepared by molecular beam epitaxy were capped with protecting amorphous germanium films. After removal of the capping layers due to heating in diluted oxygen atmosphere the surface properties of the oxide film were investigated in situ with Auger electron spectroscopy and spot profile analysis low energy electron diffraction. The removal of the capping layer has no impact on the hexagonal Pr2O3(0 0 0 1) film structure which is shown by x-ray diffraction. Surface sensitive electron diffraction confirms that the surface of the oxide film has hexagonal structure. Diffraction spot profile analysis shows that the film surface has grain structure without any mosaic spread due to the negligible lateral lattice mismatch between hexagonal Pr2O3(0 0 0 1) and Si(1 1 1). In addition, single atomic steps with complete bulk unit cell height are present at the surface. The density of the atomic steps is small pointing again to the high quality of the surface of hexagonal Pr2O3 films compared to cubic Pr2O3 films grown on Si(1 1 1).