A highly sensitive rare earth erbium doped In2S3 thin films for photodetection applications

In this article, rare earth Erbium (Er) doped In2S3 by varying the Er concentration from 0 to 5 % was synthesized using the nebuliser spray pyrolysis method. The influence of Er doping in In2S3 host in its crystalline, morphological, and optical studies were carried out. The X-ray diffraction (XRD) studies showed that the In2S3:Er thin films have a face centered cubic structure, its prominent peak belongs to (400) plane, the crystallite size changes with increasing Er dopant concentration and attained maximum for the 2% Er-doped In2S3 thin film. The morphological analysis of the thin film surface was carried out using field emission electron microscope (FESEM) measurement and found that the samples possess uniform grains without any surface defects. The Photo-luminescence spectroscopy showed that three luminescence peaks were observed at 420, 480 and 525 nm which is due to the excitonic recombination and generation of vacant sites of In and S ions in the host material. From the photoluminescence (PL) spectra, the 2% Er-doped In2S3 thin film exhibited higher luminescence intensity than other prepared samples in this present work. The UV-Vis spectroscopy depicted that the optical energy gap decreases up to 2 % and started to increase for further Er doping. The photo-sensing characteristics of the prepared samples were done and their significant parameters were measured. The determined photo sensing parameters such as responsivity (R), detectivity (D*), and external quantum efficiency (EQE) were found to be 1.05 AW- 1, 12.1 x 1010 Jones and 246% respectively. These study results proved that the 2% Er doped In2S3 thin film sample could be an excellent photosensor based optoelectronic devices.