Effect of substrate temperature on In2S3 thin films using nebulizer spray pyrolysis method for photodetector applications

In this work, Indium Sulfide (In2S3) thin films were prepared using an economical nebulizer spray pyrolysis technique by various substrate temperatures from 250 degrees C to 375 degrees C in steps of 25 degrees C to evaluate their photo sensing properties. X-ray diffraction (XRD) patterns confirm the presence of In2S3 with face centered cubic structure for all substrate temperatures. The densely packed small spherical grain-sized particles were observed for In2S3 films deposited at 350 degrees C using Field emission scanning electron microscope (FESEM) analysis. The optical bandgap values were decreased from 3.16 eV to 2.28 eV, with increment in coating temperatures from 250 degrees C to 350 degrees C. The high intensity Photoluminescence (PL) peak is observed at 480 nm for the film coated at 350 degrees C is due to higher rate of electron-hole pair recombination. The photo sensing analysis revealed that the In2S3 thin films deposited at 350 degrees C, has the maximum responsivity (R) of 9.09 x 10(-2) A W-1, detectivity (D*) of 8.25 x 10(10) Jones, and external quantum efficiency (EQE) of 21.2%. Increasing the substrate temperature results in a significant enhancement of photo sensing characteristics.