Plasma emission spectroscopy for studying Bi2S3 produced by pulsed laser deposition and effects of substrate temperature on structural, morphological, and optical properties of thin films

• Plasma analysis improves control and reproducibility of Bi 2 S 3 films in PLD. • The polycrystalline structure and particle size of the films vary with substrate temperature. • The films exhibit a transmittance of 8–26 %, a bandgap of 1.61–1.75 eV, and n-type conductivity at temperatures above ambient. • The best properties for optoelectronic applications are achieved between 150 °C and 200 °C. This research underscores the role of plasma analysis in enhancing the reproducibility of Bi 2 S 3 thin films synthesized via pulsed laser deposition (PLD). Through optical emission spectroscopy (OES), we analyzed the dynamics of the Bi 2 S 3 plasma, focusing on the transitions of neutral and singly ionized sulfur and bismuth atoms. Thin films were grown at varying substrate temperatures (WST, 100 °C, 150 °C, 200 °C, and 250 °C), and structural and morphological characterizations confirmed a polycrystalline nature, with particle size increasing at higher deposition temperatures. The films exhibited transmittance values ranging from 8 % to 26 % and a bandgap from 1.61 to 1.75 eV as the substrate temperature increased. Bi 2 S 3 films also demonstrated n-type conductivity at temperatures above room temperature. These findings highlight the influence of substrate temperature on the structural and optoelectronic properties of Bi 2 S 3 films, with optimal characteristics for optoelectronic applications consistently achieved at deposition temperatures between 150 °C and 200 °C.