Influence of Number Shots of Laser on Structural Transformations and Optical Properties of ZnS Nanoparticles Thin Films

Effects of no. shots of laser and annealing temperature on the structural, morphological, and optical properties of Zinc sulfide nanoparticles (ZnS NPs) thin films prepared by pulsed laser deposition technique (PLD) were investigated. ZnS NPs films were deposited on glass substrates at room temperature (300K) by different no. shots of laser (1000, 2000, 3000), annealed at 623K under vacuum with 10-5 mbar. Crystallite size of ZnS NPs films was investigated by XRD and morphological properties by AFM. Transformation in the shape of nanoparticles to nanoflowers and nanorods appeared with increasing no. shots of laser at the same annealing temperature (623K) was observed from scanning electron microscopy (SEM) images. Experimental results show that the as-deposited ZnS NPs film exhibiting cubic structure and the crystallinity increased in the films annealed. It is also found that grain size of as grown samples at 300K, rises linearly from (9- 11nm) with no. shots above about (1000- 3000) and rapidly from (10-18 nm) after annealing at 623K. Additionally, the increase of no. shots from (1000-3000) leads to decrease the energy gap values and increase their values after heat treatment with stay their behavior decreasing as the no. shots of laser increases. Also photoluminescence (PL) measurements explained quenching its value after annealing temperature.