Comparison studies on electrodeposited CdSe, SnSe and Cd x Sn1−x Se thin films

Abstract

Electroplated cadmium stannous selenide (Cd x Sn1−x Se) thin films were coated on indium-doped tin oxide (ITO) conducting glass substrates from aqueous bath solutions containing CdCl2, SnCl2, and Na2SeO3. The x value was tuned by change in metal ion source concentration of the electrolytic bath solution. The various x values such as 1, 0.7, 0.45, and 0, of Cd x Sn1−x Se thin films were characterized by structural, morphological, compositional, and optical properties using X-ray diffraction, scanning electron microscopy, energy dispersive analysis by X-rays, and UV-vis-NIR spectrophotometer, respectively. X-ray diffraction (XRD) patterns revealed that the deposited films exhibit polycrystalline nature Cd x Sn1−x Se thin films. The microstructural parameters such as crystallite size, dislocation density, microstrain, and number of crystallites per unit area were calculated and presented. Morphological studies revealed that spherical-shaped grains were observed in cadmium-dominated films and nano-rod-shaped grains were observed in tin-dominated films. Optical properties of CdSnSe films were determined from optical transmittance data in the spectral range 400 to 1,100 nm. The optical direct transition energy band gap was estimated using conventional method, and band gap energy was lying between 1.02 and 1.83 eV. The refractive index, extinction coefficient, and real and imaginary parts of dielectric constants were calculated using optical transmission spectra of Cd x Sn1−x Se thin films.