Antimony sulfide (Sb2S3) has emerged as a promising material for optoelectronic devices, for photovoltaic applications due to its superior properties such as a direct bandgap of 1.6-1.7 eV, a high absorption coefficient (≥105 cm-1), p-type conductivity, and low toxicity [1]. Therefore, Sb2S3, has recently emerged as one of the alternative materials being studied in PV industry due to its promising optical and electrical properties. In solar cell applications, Sb2S3, utilized as an absorber layer material, and has achieved a maximum reported efficiency of 8.32% to date [2]. Sb2S3 thin films can be fabricated using various methods, including solution-based techniques such as chemical bath deposition [3] and hydrothermal synthesis [4], as well as vacuum-based methods like sputtering [5], thermal evaporation [6], and etc. It is known that in the fabrication of Sb2S3 thin films achieving the desired stoichiometric ratio in single-step production processes is challenging, leading to defect formation [7]. Annealing in a sulfur atmosphere can be performed to compensate for sulfur loss (S-loss) and achieve stoichiometric structures. In this context, two different approaches, Conventional Thermal Processing (CTP) and Rapid Thermal Processing (RTP), are carried out in the literature. The latter one present high heating rate to the reaction temperature, which provides precise control over crystallization and grain growth in Sb₂S₃ thin films, contributing to improved crystallinity, reduced defect density, and enhanced optoelectronic properties, which are critical for high-performance of solar cells. In the present study, Sb2S3 thin films were fabricated by two-stage process comprising depositing Sb films by sputtering method and annealing of them by RTP in sulfur atmosphere at 375 °C. In the first part of the study, the effect of the heating rate (1, 2, 3, and 4 °C/s) was investigated, and in the second part, the impact of sulfurization time (1, 3, 5, and 10 min) using the optimized heating rate on the structural, optical, and electrical properties of the Sb₂S₃ thin films were examined. All films characterized by XRD, Raman spectroscopy, SEM, EDX, PL and Hall effect measurements. As a result of the analyses, it was determined that the S/Sb ratio in all samples was around 1.4–1.5, the films crystallized along the (hk1) plane of the orthorhombic structure, the band gap varied between 1.6–1.7 eV, and the resistivity and carrier concentration were approximately 10⁴ Ω·cm and 10¹²–10¹⁴ cm⁻³, respectively. It was concluded that variations in the heating rate and sulfurization time led to significant changes in the properties of Sb₂S₃ thin films.

References

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