Comparison of Structural Properties of Thermally Evaporated CdTe Thin Films on Different Substrates

The direct energy band gap in the range of similar to 1.5eV and the high absorption coefficient (similar to 10(5)cm(-1)) makes Cadmium Telluride (CdTe) a suitable material for fabrication of thin film solar cells. Thin film solar cells based on CdTe (similar to 1 cm area) achieved efficiency of 15.6% on a laboratory scale. CdTe thin films were deposited by thermal evaporation technique under vacuum (2 x 10(-5)mbar) on glass and stainless steel (SS) substrates. During deposition substrate's temperature was kept same at 200 degrees C for all samples. The structural properties were determined by the X-ray Diffraction (XRD) patterns. All samples exhibit polycrystalline nature. Dependence of different structural parameters such as lattice parameter, micro strain, and grain size and dislocation density on thickness was studied. Also the influence of the different substrates on these parameters was investigated. The analysis showed that the preferential orientation of films was dependent on the substrate type.