Highly improved photo-sensing ability of In2S3 thin films through cerium doping

Abstract

In this work, the influence of rare earth doping on the efficiency of photodetection in In2S3 thin films coated on glass substrates through a nebulizer-assisted spray pyrolysis technique was studied. The In2S3 films were doped with rare earth cerium ions by varying their weight percentage from 0 to 3%. The changes in the structural, morphological, optical, and light sensing capabilities of Ce-doped In2S3 thin films were thoroughly studied using appropriate characterization techniques. X-ray diffraction confirmed the formation of cubic crystallites with a highest crystallite size of 37 nm for 2% Ce doped In2S3 sample. The compositional studies indicate the presence of indium, sulfur, and cerium alone in the prepared films confirming its purity. The optical band gap from Tauc's plot was found to lie in the range of 2.85 –2.77 eV. The band gap is found to decrease with the increase in the replacement of In3+ ions with Ce3+ ions. The optical analysis showed an increased absorption in the ultraviolet region. The sample doped with 2% of cerium is found to have a maximum value of responsivity 0.752 A/W, detectivity 4.53 × 1010 Jones and an EQE of 243%. The rise and fall time of the same sample recorded 0.3 s and 0.4 s respectively. The work paves way to the fabrication of an efficient In2S3 thin film-based UV photo detector doped with cerium at a low cost.