Properties of different temperature annealed Cu(In,Ga)Se2 and Cu(In,Ga)2Se3.5 films prepared by RF sputtering

► The Cu(In,Ga)Se2 and Cu(In,Ga)2Se3.5 films follow different process to form CIGS phase. ► Composition loss of the annealed Cu(In,Ga)Se2 and Cu(In,Ga)2Se3.5 films are different. ► Hexagonal CuSe phase exhibits unique transport feature. ► Conductivity of the CIGS films is affected by the “variable range hopping” mechanism.