Oscillatory optical second-harmonic generation from Si(001) surface duringthin-film epitaxy

Periodic variation in optical second-harmonic generation during homoepitaxi al growth of silicon on singular Si(001) surface is reported. The period of the oscillations corresponds to bilayer growth, and the oscillations are c orrelated with the mechanism associated with a two-dimensional layer-by-lay er growth mode. This mechanism is tentatively attributed to periodic domain coverage variations analogous to the oscillatory response in linear optica l technique of reflectance anisotropy. The current experiment, however, can not distinguish this mechanism from another based on anisotropic second-har monic generation response with respect to steps. (C) 2000 American Institut e of Physics. [S0003-6951(00)03304-0].