Single wavelength ellipsometry was used to monitor the growth of Si(1-x)Gex alloys obtained by ultrahigh vacuum chemical vapor deposition (CVD) at 570 °C on Si and to evaluate the effect of sample irradiation by KrF excimer laser pulses at an energy density above the threshold for surface melting. Laser irradiation was performed during or after the CVD growth. When the Si(1-x)Gex alloys were grown without laser assistance, the recorded ellipsometric curves indicated the presence of pronounced surface roughness, which was confirmed by atomic force microscopy analysis. On line ellipsometry during multiple pulse postgrowth irradiations showed a sudden increase of the ellipsometric angles Ψ and Δ corresponding to the first laser pulse. This behavior attested to the smoothing of the surface microroughness induced by the melt–recrystallization cycle. The excimer laser assisted CVD growth of Si(1-x)Gex alloy layers was also followed. By changing the ratio between the thermal growth rate and the irradiation frequency the kinetics of surface roughening was studied. © 1998 American Vacuum Society.