Effect of the deposition conditions on the optical, morphological and compositional properties of CuIn_1-xGa_xSe₂ thin films prepared by a multistage process

This work presents results related with optical, morphological and compositional properties of polycrystalline p-type CuIn_1-xGa _xSe₂ (CIGS) thin films. The films were grown by a chemical reaction of the precursor species which are sequentially evaporated in two and three stage processes on a soda-lime glass substrate, and later will be used as an absorber layer in solar cells. The samples were characterized optically, morphologically, and compositionally through transmittance, Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectroscopy (XPS) measurements. The results showed that, in general, the deposited samples grow with absorption coefficients and optical gaps that are adequate for absorber layers in solar cells. In general, the films deposited in a two stage process present a mixture of the Cu(In,Ga)Se₂ phase in the bulk with the secondary In ₂Se₃ and Cu₂Se phases at the surface, while the films grown in a three stage process mainly present the Cu(In,Ga)Se₂ phase.