(AgwCu(1-w))(In1-xGax)Se-2 alloy absorber layers with w approximate to 0.8 and x approximate to 0.78 ratios were deposited using multi-source elemental evaporation and analyzed by glancing incidence X-ray diffraction, scanning electron-microscopy combined with energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The effect of Rapid Thermal Processing (RTP) on the structure and composition of the near-surface layers was investigated. It was found that the RTP doesn't have a noticeable effect on the grain size and roughness of the film surface. On the other hand, additional reflections of the films with 0.5 <= Ga/(Ga + In)<1 and Ag/(Ag + Cu) > 0.5, due to an ordered defect phase which is confined to the near-surface region of the film, are completely diminished after RTP with excess Se present. X-ray photoelectron spectroscopy results show that RTP with excess Se present altered the distribution of elements, rendering the film surface less group I deficient after that process. Consequently, atomic ratios were changed from the composition of I1III5VI8 compound to the composition close to that of I1III3VI5 ordered defect phase. Additionally, the RTP treatment, especially with excess Se, significantly enhanced solar cell efficiency performance due to an improvement in the open circuit voltage. (C) 2012 Elsevier B.V. All rights reserved.