Evaluation and characterization of polycrystalline CuInSe2 thin films prepared by the sandwich structure technique

The optical and electrical properties of CulnSe2 (CIS) have shown it to be a promising photovoltaic material. The preparation of CulnSe 2, thin films by means of the stacked elemental layer (SEL) technique was developed at Newcastle Photovoltaic Centre, Northumbria University. The method is presented as a low-cost technology because of its ability to retain stoichiometry and its scalability for large-area device applications. This paper presents a modification of the technique employed to produce CulnSe2 thin films and describes the structure, optical and electrical properties of such films. X-ray diffraction examination, energy dispersive x-ray analysis and measurements of the optical transmission and reflection and resistivity were used to determine the film properties relative to the preparation parameters and stoichiometry, The growth conditions were optimized for solar cell applications. Electrical resistivities in the range 10-2 to 10 5 Omega cm, energy gaps between 0.96 and 1.03 eV, and an absorption coefficient close to 105 for the CIS films were obtained in this work.