In this article, by investigating the influence of Ar flow rate on deposition rate and structural properties of hydrogenated silicon germanium (SiGe:H) films, we showed that the addition of Ar in the diluted gas efficiently improve the deposition rate and crystallinity due to an enhanced dissociation of source gases and bombardment on growth surface. The hydrogen content and SE results suggest that the defect density and void volume fraction increases with increasing Ar flow rate, which is attributed to the injection of higher energy Ar+ ions into the filmled to a displacement of the atoms and an increased possibility of argon being trapped with the films. The optoelectronic properties are investigated by absorption coefficient and dark conductivity measurements and a reasonable explanation is presented. (C) 2010 Elsevier B.V. All rights reserved.