CHARACTERIZATION OF MBE-GROWN ALPHA-SN FILMS AND ALPHA-SN1-XGEX ALLOYS

The electronic structure and interface properties of epitaxial alpha -Sn and alpha -Sn1-xGex alloy films grown by molecular beam epitaxy on GaSb, CdTe, InSb and Ge substrates were studied by synchrotron radiation photoemission spectroscopy and X-ray diffraction. Deposition at temperatures below approximately 150 degrees C results in amorphous alloy films. At higher substrate temperatures GaSb and CdTe partially react with the overlayer to form precipitates containing either GeSb or SnTe in the interface region. Homogeneous single-crystal alloy films of 200-300 AA thickness were grown on (100)Ge at approximately 400 degrees C. Angle-resolved valence band photoemission spectra show the opening of the band gap by alloying Ge to alpha -Sn. For an alloy with x=0.52 the Gamma 8 point is shifted by approximately 0.16 eV below EF.