Influence of Film Thickness on Structural and Optical Properties of Copper Sulfide Thin Films Prepared by Pulsed Laser Deposition (PLD)

The structural properties of zinc telluride (ZnTe) thin films are critically influenced by deposition conditions, particularly substrate temperature. However, previous studies often overlooked the systematic investigation of how gradual increments in deposition temperature affect the crystallinity and grain growth behavior of ZnTe films deposited via pulsed laser deposition (PLD). In this study, a novel comparative methodology was employed by fabricating three ZnTe thin films at distinct substrate temperatures: 100°C, 200°C, and 300°C, under otherwise identical PLD conditions. The structural evolution of the films was analyzed using X-ray diffraction (XRD) to elucidate the relationship between deposition temperature and crystal orientation. All films exhibited a preferred (111) orientation; however, significant differences were observed in the peak intensity, sharpness, and grain size as the temperature increased. The film deposited at 300°C showed the most pronounced peak intensity and improved crystallinity, indicating enhanced atomic mobility and better structural ordering at elevated temperatures. This suggests stronger interatomic bonding along the (111) plane and a reduction in structural defects, which are typically responsible for weak or disordered growth. The findings provide new insights into the thermally activated crystallization process in ZnTe films and highlight 300°C as an optimal deposition temperature for achieving high-quality crystalline structures. This approach demonstrates a more controlled and insightful investigation into the role of thermal energy in PLD-grown ZnTe films compared to previous works, laying the groundwork for their future application in optoelectronic and photovoltaic devices.