Improved photo sensing behavior of the terbium doped In₂S₃ thin films synthesized by spray pyrolysis technique

Abstract

In the present work, undoped In2S3 and varying concentrations of Tb (1, 2, 3, 4 & 5 wt%) doped In2S3 thin films were synthesized using the economical and nebulizer spray pyrolysis technique for studying their photosensing characteristics at room temperature. X-ray diffractometer (XRD) studies showed the diffraction pattern of the thin films exhibits a cubic- β phase of In2S3 and the highest crystallite size of 61 nm was observed for the In2S3: Tb (2wt%) thin film. The morphological & elemental analysis showed that all the synthesized thin films exhibit homogeneous non-uniform crystal morphology with the existence of S, In, Tb compounds with their distinct composition. From Ultraviolet-Visible(UV–vis) studies, all the prepared thin films exhibit maximum absorption in the UV region with a minimum bandgap of 2.85 eV for the In2S3:Tb (2wt%) thin film. Also, the Photoluminescence (PL) spectra showed that the In2S3:Tb (2wt%) thin film possesses two large intense emission peaks around ∼470 nm (Yellow) and 530 nm (green). Finally, the photo sensing studies showed that the fabricated In2S3:Tb (2wt%) thin film photodetector showed better photocurrent, Responsivity (R), Detectivity (D*), External Quantum Efficiency (EQE), Response/Recovery time values of ∼12.5 μA, 0.296 AW−1, 7.75 × 1010 Jones, 60%, 2.9/3.6 s, respectively indicating the device better suitable for commercial photodetector application.