We have prepared Cu(In,Ga)S-2 films at growth temperatures from 300 degrees C to 580 degrees C with a homogeneous gallium depth distribution (estimated band gap 1.67 eV) onto soda lime glass (SLG) substrates with one of three different kinds of back contact: Mo(1000 nm), ZnO(500 nm), and Mo(30 nm)/ZnO(500 nm), respectively. We have also investigated the depth profiles of Zn and Na (diffused from SLG) in Cu(In,Ga)S-2 films by secondary ion mass spectroscopy (SIMS). The efficiency of solar cells on Mo increases with increasing growth temperature. It is higher on Mo/ZnO than on ZnO, and increases from 350 degrees C to 450 degrees C, then decreases above 450 degrees C. It was observed by SIMS that the amount of Zn in Cu(In,Ga)S-2 on Mo/ZnO is lower than it is on ZnO up to 450 degrees C, and a large amount of Zn diffuses into absorbers over 450 degrees C, which contributes to decreasing efficiency. The amount of Na in the back contact increases with growth temperature. The depth distribution of Na in Cu(In,Ga)S-2 films on Mo is almost constant in the order of 10(17)-10(18) cm(-3), on ZnO and Mo/ZnO the Na concentration increases towards the surface and is in the range of 10(15)-10(17) cm(-3). (C) 2008 Elsevier B.V. All rights reserved.