Structural and Electrical properties of Thermally Evaporated Nanostructured CuInSe Thin Films

Abstract

Nano structured thin films having different thickness of CuInSe were deposited by thermal evaporation techniques, onto precleaned amorphous glass substrate at room temperature. The structural properties of films were evaluated by XRD, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The quantitative analysis was done by Energy Dispersive Analysis for x-ray to determine atomic % of the material used. The electrical transport properties of as deposited thin films have been evaluated by using four probe resistivity set up. Resistivity (3.108 X 10 -5 ohm cm), activation energy (0.00396 – 0.0752 eV), carrier concentration (1.30 X 10 18 /cm3), mobility (1.53 X 10 4 cm 2 / V-s) has been estimated. Thermo Electrical parameters such as Fermi energy (0.025 to 0.461 eV), absorption coefficient (0.0042 to 0.067) have been estimated. The x-ray diffraction analysis confirms that films are polycrystalline in nature having cubic structure with a preferential orientation along the (300) plane. The degree of such a preferred orientation was found to increase with film thickness. The lattice parameters (a = 11.53 Å) and crystallite size (D) were calculated and found to be 16.21 nm. The dislocation density, the number of crystallites per unit area (N) and the strain (ε) of the films were determined. SEM investigation confirms that nano size grains were distributed almost uniformly over smooth substrate and particles were granular in nature. Large grains on top of dense bottom films were observed. The nano grains forms cluster by fusing to each other. The size of clusters was found approximately 48.04 nm to 235.05 nm.