Solar cells have been made from uniformCu(In,&hthinsp;Ga)Se2films deposited by elemental evaporation with two different Ga compositions,Ga/[In+Ga]=0.30and 0.65. The solar cells fabricated from these uniform films have 15&percent; efficiency forGa/[In+Ga]=0.30,but the device efficiency is less than expected for the high Ga content due primarily to a decrease in fill factor and open circuit voltage. Analysis of current-voltage results have shown that the main cause of this decrease is a voltage dependent light generated current,JL,(V).Devices were fabricated with both standard (1 &mgr;m) and semi-transparent (0.04 &mgr;m) Mo contacts. Bi-facial spectral response measurements were made and analyzed on the devices with the semi-transparent Mo contacts in order to determine the changes in collection efficiency as a function of changing Ga composition and applied voltage. This analysis determined that the decrease in the light generated current with increasing voltage is primarily due to a reduction in minority carrier diffusion length, L, from about 0.8 to 0.1 &mgr;m. ©1999 American Institute of Physics.