Metal-semiconductor reaction phenomena and microstructural investigations of laser-induced regrowth of silicon on insulators

The defect structure in CVD Si layers on sapphire were investigated before and after scanning laser annealing. Prior to laser annealing, the films were characterized by the presence of stacking faults, twinning zones dislocation lines producing large regions of high disorder. Subsequent to laser annealing under conditions to produce total melting of the Si layers it was shown that liquid phase epitaxial regrowth occurred resulting in regions of defect-free Si and a total absence of twinning regions. Correlated Rutherford backscattering, channeling and transmission electron microscopic analyses showed a dramatic improvement in crystalline perfection relative to the results obtained from films grown by any other technique on sapphire substrates. In separate collaborative experiments with Stanford University, it was also shown that scanning cw laser irradiation could be used to produce diffusion and activation of Sn from a spin-on SnO2/SiO2 source. The formation of a Sn3As2 alloy has been shown to be related to the observed n+ activity.