Thermal diffusion of Cu into In 2Se 3: A better approach to SEL technique in the deposition of CuInSe 2 thin films

Abstract

This paper reports the modifications made in the preparation techniques of getting CuInSe 2 thin films starting with chemical bath deposited (CBD) selenium films. In the present study, CBD Se film was converted into CuInSe 2 by stacked elemental layer (SEL) technique and also by thermal diffusion of Cu into In 2Se 3. In both the cases CBD Se films were used to avoid toxic Se vapor and H 2Se 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 CuInSe 2 deposited by these two techniques, it was found that photosensitivity was better for samples prepared by thermal diffusion of Cu into In 2Se 3. So the technique of thermal diffusion of Cu into In 2Se 3 was found to be better than SEL technique in the preparation of CuInSe 2 using CBD Se. Cu-rich, In-rich and nearly stoichiometric samples could be prepared by thermal diffusion of Cu into In 2Se 3. These samples were analyzed using energy dispersive spectroscopy, Raman spectroscopy and atomic force microscopy also.