Control of Surface Roughness of Si and Ge Single Crystal by Laser Radiation

Abstract

Analysis of reordering of Ge amorphous surface by ruby laser; kinetics of the surface annealing after ion implantation using the optical reflectivity; occurrence of laser induced periodical structures; nanohills formation by Nd:YAG laser allowed us to resume common features for these process which belong to Thermogradient effect. Experimental data on annealing of p-Si (111) and i-Ge (111) mechanically polished surfaces by Nd:YAG laser radiation using of optical microscopes and atomic force microscopes, optical reflectivity of He-Ne laser and the four-probe method confirmed the main role of Thermogradient effect in the reordering process of the mechanically polished surface of Si and Ge to single crystal. It was found that row of nanohills arises on the irradiated surface of Ge and Si single crystal after irradiation by Nd:YAG. Photoluminescence of nanohills row in visible range of spectra was established. The photoluminescence of Ge and Si samples after irradiation by Nd:YAG laser is explained with quantum confinement effect on the top of nanohills - quasi quantum dots. For explanation of this effect gathering of interstitial atoms at the irradiated surface is proposed.