Study the effect of type of substrates on the microstructure and optical properties of CdTe Thin Films

Cadmium telluride (CdTe) thin films are deposited on an ultrasonically cleaned substrate of different types by using thermal evaporation technique under pressure 2 × 10-5 mbar. The structural and morphological studies of all the films are accomplished using the X-ray diffraction method (XRD) and field emission scanning electron microscope (FE-SEM). CdTe found to has a polycrystalline structure. The grains were very uneven and the grain shape was irregular. A Jasco V-570 UV- visible - NIR spectrometer has been used to measure the optical properties in the range of wavelength from 200 to 2500 nm at normal incidence. The optical energy gap (Eg) is determined by using the Tauc’s equation. The optical parameters such as; refractive index (n), static refractive index (no), infinite dielectric constant (ε∞), dispersion energy (Ed), single oscillating energy (E0), static dielectric constant (εs), free carrier concentration (N), plasma frequency (ωp), relaxation time (τ), oscillator wavelength (λo), oscillator strength (S0) and electronic polarizability (αp) respectively are calculated. The optical measurements for CdTe films deposited on FTO substrate were property used as absorber material for solar cell applications. Inversely, CdTe films deposited on a glass substrate is more suitable for a window in solar cell applications.