Influence of Magnesium Doping Concentrations and annealing on the Transmittance and Energy Band-gap of Sb2S3 Thin Films Deposited via Chemical Bath Deposition Technique

Abstract

The incorporation of thin film materials into a wide range of technological applications has attracted considerable interest owing to their distinct properties and versatile functionalities. In this study, Magnesium alloyed and Antimony sulphide (Sb2S3) thin films were successfully deposited on glass substrates by chemical bath deposition technique. The films were grown at room temperature of constant pH. The concentrations of magnesium varied between 0.1M and 0.3M. The films were annealed at annealing temperature between 100˚C and 300˚C at a fixed annealing time of 1 hour. The films were characterized using UV-spectrophotometer to investigate the variation of optical and solid state properties with wavelength in the UV-VIS-NIR region. The result showed that the presence of the alloying agent and annealing treatments modified the optical and solid state properties of the films significantly. The transmittance of the films was high. Annealing led to reduced transmittance due to increased crystallite size, notably in films doped with 0.1M Mg2+ ions and annealed at 200˚C, suggesting enhanced photon absorption. The energy band gaps were found to be direct and in the range of 1.25 eV to 1.72 eV for the as grown films and 1.15eV to 1.3eV for the films annealed at annealing temperatures 300˚C. The study identifies a direct correlation between magnesium doping concentration, annealing conditions, and shifts in the energy band-gap of the films. The values of the energy band gaps are all within the range suitable for use of the layers as absorbers in hetero-junction solar cell devices for sustainable energy applications.