Fabrication and Characterization of Copper Indium Telluride Thin Films

Copper Indium Telluride (CIT) is a semiconducting low band gap (~0.9 eV) material, desirable for bottom cell in tandem solar cell structure in order to extract the more of the solar spectrum. CIT thin films have been fabricated by co-evaporation of Copper, Indium, and Tellurium source materials followed by annealing in Tellurium environment. Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) have been used to find the grain size and stoichiometric proportions. Crystallinity and the phase of the CIT film is determined by using X-ray diffraction (XRD). Spectroscopic Ellipsometry measurements are performed and the complex dielectric function (e = e₁ + e₂) over the spectral range of interest 0.7 to 2 eV are extracted. The variation in the band gap is also studied in different stochiometric proportionate CIT thin films.