Amorphous GeSi films with different thicknesses and oxygen contents were
electron beam evaporated onto Si (KK)) wafers and wet oxidized at 900 °C for
30 Min. If there was no oxygen in the as-deposited film, an epitaxial GeSi
film would be grown after wet oxidation. For the samples with oxygen,
epitaxial growth broke down when the thickness of the epitaxy exceeded about
200 A and polycrystalline GeSi films were formed. A dedicated STEM (scanning
transmission electron Microscope) was used to characterize the sample after
oxidation. STEM BF (bright field), ADF (annular dark field), and energy
filtered images revealed the presence of small oxide particles in the
polycrystalline GeSi films. X-ray microprobe analysis with a windowless
detector was employed to identify the oxide particles. The failure of the
epitaxy is explained by the random nucleation and growth of GeSi grains on
the oxide particles.