Thermal diffusion of Cu into In2Se3: A better approach to SEL technique in the deposition of CuInSe2 thin films

This paper reports the modifications made in the preparation techniques of getting CuInSe₂ thin films starting with chemical bath deposited (CBD) selenium films. In the present study, CBD Se film was converted into CuInSe₂ by stacked elemental layer (SEL) technique and also by thermal diffusion of Cu into In₂Se₃. In both the cases CBD Se films were used to avoid toxic Se vapor and H₂Se gas. Improvements were made in these techniques through a detailed study, varying the composition of the films over a wide range by changing the Cu/In ratio. Structural, optical and electrical characterizations were performed. On comparing the material properties of CuInSe₂ deposited by these two techniques, it was found that photosensitivity was better for samples prepared by thermal diffusion of Cu into In₂Se₃. So the technique of thermal diffusion of Cu into In₂Se₃ was found to be better than SEL technique in the preparation of CuInSe₂ using CBD Se. Cu-rich, In-rich and nearly stoichiometric samples could be prepared by thermal diffusion of Cu into In₂Se₃. These samples were analyzed using energy dispersive spectroscopy, Raman spectroscopy and atomic force microscopy also.