Effects of post-deposition annealing on the structural and electrical properties of magnesium-doped SB2S3 thin films deposited by chemical bath deposition technique

Abstract

In this study, magnesium-alloyed antimony sulfide (Sb2S3) thin films were successfully deposited on glass substrates via the chemical bath deposition technique, and the effects of post-deposition annealing on their structural and electrical properties were investigated. The films were grown at room temperature with constant pH, while the magnesium concentrations varied between 0.1M and 0.3M. Post annealing treatment was conducted at temperatures ranging from 100°C to 300°C, with a fixed duration of 1 hour. Characterization of the films was performed using a MiniFlex 600 diffractometer for XRD analysis and UV-spectrophotometer to analyze optical and solid-state properties across the UV-VIS-NIR region. The results demonstrated significant modifications in the structural and optical properties of the films due to the presence of the alloying agent and annealing treatments. X-ray diffraction (XRD) analysis revealed a crystalline orthorhombic structure (PDF#42-1393) for the films, with diffraction peaks corresponding to the stibnite phase, indicating their polycrystalline nature. Higher concentrations of magnesium dopants led to increased intensities of diffraction peaks, reflecting enhanced impurity concentrations, which became more pronounced with increasing annealing temperatures. Optical conductivity curves showed a consistent increase in the extinction coefficient across the wavelength range of 310 nm to 1000 nm for all cases. In as-deposited films, the extinction coefficient (k) uniformly decreased with increasing concentrations of Mg²⁺ ions, ranging from 0.02 to 0.18. However, annealing induced modifications in the extinction coefficient values, with significant reductions observed at higher annealing temperatures. This behavior, reflecting the variation in extinction coefficient with varying Mg²⁺ ion concentrations, suggests potential applications for these films in optoelectronics, photovoltaics, and sensors.