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.