Concentration Dependent Optical Properties of NiSe Thin films grown by the Solution Growth Technique

Thin films of NiSe (nickel selenides) were prepared at different concentrations in the range 0.50 M to 1.00 M with the other deposition variables such as the bath temperature, pH, and source to substrate distance kept constant. The films were characterised using optical spectroscopy to investigate the absorbance, reflectance, and transmittance versus wavelength measurements, thus enabling the determination of important optical constants (optical absorption coefficient, energy bandgap, refractive index, extinction coefficient, and the dielectric constants). The results show that the optical constants were strongly dependent on the concentrations. The transmittances of the films were > 50% and the energy bandgap was direct, with values in the range suitable for application in solar cell devices. The refractive index was found to vary between 1.2 to 2.4.