Fabrication and Optical Characterization of CdSe Thin Films Grown by Chemical Bath Deposition

Cadmium selenide thin films with different pH values (pH = 10, 11, 12 and 13) are produced on glass substrates at 50°C for 3 h by chemical bath deposition technique. The structural, morphological and optical properties of the films are characterized by X-ray diffraction, scanning electron microscopy and optical absorption spectroscopy, respectively. The obtained films have hexagonal structure. The optical transparency of the films varies between 85% and 98% at wavelength of λ = 550 nm. The scanning electron microscopy studies show that the film deposited at pH = 10 exhibits the formation of nanorods in the width range from 1.8 μm to 10.9 μm and length range from 20.0 μm to 85.5 μm. The optical properties of the films are determined by measuring transmittance and absorbance characteristics which are used to find the optical band gap energy, refractive index, extinction coefficient and real dielectric constant. The band gap width of the films increases from 1.70 eV to 2.30 eV with increasing pH values. The refractive index of the film at pH = 10 is found as 1.54.