Characterization of excimer laser annealed polycrystalline Si1-xGex alloy thin films by x-ray diffraction and spectroscopic ellipsometry

Thin films of Si1-xGex alloys of different compositions x have been deposited, on single-crystal Si (100) surface and glass substrates, by simple ion beam sputtering, at room temperature. Crystallization of these films has been done using excimer laser annealing. Structural and optical properties of as-deposited and annealed Si1-xGex alloy films are characterized by x-ray diffraction (XRD), uv-visible spectrophotometry, spectroscopic ellipsometry (SE), and Auger electron spectroscopy (AES). The as-deposited films, both on Si and glass, have been found to be amorphous by XRD, Polycrystalline nature of laser-annealed samples has been evidenced by both x-ray and SE measurements. The results of x-ray, uv-visible, AES, and SE are compared and discussed. The poly-Si1-xGex films were oriented predominantly to (111) and the grain sizes were determined from half-width of x-ray peaks. The compositions x of Si1-xGex films have been evaluated from the SE dielectric function epsilon(omega) data, using the second-derivative technique, and are found to be 0.23 and 0.36 for two different compositions. A detailed analysis of epsilon(omega) with the effective-medium theory has demonstrated the volume fraction of crystalline Si1-xGex increases with the increasing energy of laser irradiation. (C) 1998 American Institute of Physics.