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<p>SnSe<sub>x</sub>Te<sub>1-x</sub> nanoparticle thin films were synthesised through direct fusion of the precursors, followed by thermal evaporation under vacuum, providing a reliable method for producing high-quality layers. Vacuum annealing from 373 to 523&#xa0;K resulted in thin films comprising a dominant cubic SnSe<sub>0.3</sub>Te<sub>0.7</sub> phase, along with minor orthorhombic SnSe and monoclinic Te phases. Annealing the films up to 473&#xa0;K enhanced the crystallinity of the SnSe₀.₃Te₀.₇ phase through grain growth and defect reduction, whereas annealing at 573&#xa0;K caused decomposition of the SnSe<sub>0.3</sub>Te<sub>0.7</sub> ternary phase, accompanied by Te re-evaporation and the subsequent formation of SnSe.The sharp Raman peak at 121&#xa0;cm⁻<sup>1</sup> also confirms the formation of the SnSe<sub>0.3</sub>Te<sub>0.7</sub> ternary phase. At 473&#xa0;K, the SnSe<sub>0.3</sub>Te<sub>0.7</sub>&#xa0;cubic phase exhibited an average crystallite size of ~ 29&#xa0;nm, a lattice parameter of <i>a</i> = 6.261&#xa0;Å, and a cell volume of <i>V</i> = 245.431 Å<sup>3</sup>, with a slight lattice expansion indicating tensile strain that affects crystallinity and optoelectronic behaviour. Optical studies exhibit strong absorption in the 1200–2400&#xa0;nm range, making the material suitable for photovoltaic applications. The direct bandgap increases from 0.83 to 1.09&#xa0;eV upon annealing, attributed to enhanced crystallinity, reduced defects, and the elimination of impurity- or disorder-induced states. Photoluminescence demonstrates near band-edge and defect-related emissions affected by phase evolution. Compositional analysis confirms stable stoichiometry up to 523&#xa0;K, while tellurium (Te) loss at higher temperatures alters the Se/Te ratio. Hall measurements indicate p-type conductivity with optimised electrical parameters: resistivity ρ = 8.78 × 10<sup>–3</sup> Ω·cm, mobility μ = 15.38 cm<sup>2</sup>/V·s, and carrier concentration N<sub>A</sub> = 4.61 × 10<sup>19</sup>&#xa0;cm<sup>−3</sup> at 473&#xa0;K.</p>

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Phase evolution and annealing-induced optimisation of SnSexTe1-x nanoparticle thin films for photovoltaic applications

  • 期刊论文

  • 发表日期：

    2025年12月23日

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  • Meena Gupta,
  • Naresh Padha,
  • Dimple Singh,
  • Zahoor Ahmed

摘要

SnSexTe1-x nanoparticle thin films were synthesised through direct fusion of the precursors, followed by thermal evaporation under vacuum, providing a reliable method for producing high-quality layers. Vacuum annealing from 373 to 523 K resulted in thin films comprising a dominant cubic SnSe0.3Te0.7 phase, along with minor orthorhombic SnSe and monoclinic Te phases. Annealing the films up to 473 K enhanced the crystallinity of the SnSe₀.₃Te₀.₇ phase through grain growth and defect reduction, whereas annealing at 573 K caused decomposition of the SnSe0.3Te0.7 ternary phase, accompanied by Te re-evaporation and the subsequent formation of SnSe.The sharp Raman peak at 121 cm⁻1 also confirms the formation of the SnSe0.3Te0.7 ternary phase. At 473 K, the SnSe0.3Te0.7 cubic phase exhibited an average crystallite size of ~ 29 nm, a lattice parameter of a = 6.261 Å, and a cell volume of V = 245.431 Å3, with a slight lattice expansion indicating tensile strain that affects crystallinity and optoelectronic behaviour. Optical studies exhibit strong absorption in the 1200–2400 nm range, making the material suitable for photovoltaic applications. The direct bandgap increases from 0.83 to 1.09 eV upon annealing, attributed to enhanced crystallinity, reduced defects, and the elimination of impurity- or disorder-induced states. Photoluminescence demonstrates near band-edge and defect-related emissions affected by phase evolution. Compositional analysis confirms stable stoichiometry up to 523 K, while tellurium (Te) loss at higher temperatures alters the Se/Te ratio. Hall measurements indicate p-type conductivity with optimised electrical parameters: resistivity ρ = 8.78 × 10–3 Ω·cm, mobility μ = 15.38 cm2/V·s, and carrier concentration NA = 4.61 × 1019 cm−3 at 473 K.