Control of deposition and surface properties of CuInSe2 thin films for solar cells

The generation of high-efficiency CuInSe₂/(CdZn)S solar cells using CuInSe₂ thin films deposited by elemental evaporation in a two-step process is presented. The substrate temperature of the first deposition which is less than 350 degrees C, reduced the growth defect height to less than 3 mu m. The surface structure of the as-grown CuInSe₂ films can further be modified by etching in an aqueous bromine solution yielding a specular surface. Specular films provide suitable substrates for high-efficiency ( eta >9%) single and multijunction devices and are used to demonstrate the uniformity of the bulk properties of CuInSe₂ films deposited in two steps.