Optoelectronic properties of undoped and Al, B and Ga-doped In₂S₃ thin films grown by CBD on flexible PET/ITO substrates

Undoped and Al, B and Ga-doped In₂S₃ thin films were deposited on flexible PET/ITO substrates using chemical bath deposition by varying the deposition temperatures (60, 70, 80 and 90 °C) and growth times (120, 150 and 180 min). Citric acid was used as complexing agent along with indium trichloride and thioacetamide as indium and sulfur sources, respectively. The structural, optical and electrical properties of In₂S₃ thin films were analyzed by Raman spectroscopy, UV-Vis transmittance spectroscopy and Hall Effect measurement. Structural analysis indicated the tetragonal phase of In₂S₃ films. The optical characterization showed a maximum transmittance of 80% in the visible region. The band gap energy of In₂S₃ thin films was tuned from 2.06 to 2.94 eV with respect to doping elements and experimental parameters. The electrical characterization showed n-type conductivity for both undoped and doped In₂S₃ thin films along with the resistivity values between 1 × 10⁻² and 1 × 10⁵ Ωcm.