High Photosensitivity Nanocrystalline p-Cu2S/n-FTO Heterojunction Photodetectors Prepared by Dip Coating Method

Abstract

Objective: The aim of present work is to fabricate nanocrystalline p-Cu2S/n-FTO heterojunction photo detectors with high photosensitivity. Methods: Copper sulphide (Cu2S) is semiconductor compound belonging to I-VI group. Cost effective chemical method was used to synthesize thioglycerol capped Cu2S nanoparticles with improved optoelectronic and physical properties. These nanoparticles were investigated by ultraviolet-visible (UV-Vis) absorption spectroscopy, photoluminescence (PL) and transmission electron microscopy (TEM). Cu2S films were deposited on fluorine doped tin oxide (FTO) glass slides using cost effective dip coating method at different dip times and heat treated in air atmosphere. Wide band gap fluorine doped tin oxide, n-type semiconductor was used as transparent window material together with narrow band gap Cu2S, p-type semiconductor used as absorber layer in case of Cu2S/FTO heterojunction photo detectors under reverse biased mode and illumination. Results: Cu2S films were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Analysis by X-rays (EDAX), Mapping and Atomic Force Microscopy (AFM). Selected Area Electron Diffraction (SAED) images showed ring patterns indicating that Cu2S nanoparticles are polycrystalline in nature and spot patterns indicating that Cu2S nanoparticles are monocrystalline in nature. Conclusion: Previously, preparation of optoelectronic devices such as photo detectors using Cu2S films has not been reported. In this study, photo detectors having enhanced photosensitivity were prepared using Cu2S films. I-V characteristics of p-Cu2S/n-FTO heterojunctions under dark and illumination conditions were examined. It was observed that film conductivity decreases under dark condition and increases under illumination condition with increase in dip time in case of Cu2S/FTO heterojunction photo detectors.

Hyperfine splitting and ferromagnetism in CdS : Mn nanoparticles for optoelectronic device applications

“…The main peaks of samples A to J at ~29 and ~47 Å referring to the planes (111) and (220) indicate a cubic crystal structure. A cubic crystal structure was also observed in the case of the undoped CdS nanoparticles synthesized in our previous study [33] . The average particle size is found out from the XRD pattern using Scherrer's formula [33,35] .…”

“…A cubic crystal structure was also observed in the case of the undoped CdS nanoparticles synthesized in our previous study [33] . The average particle size is found out from the XRD pattern using Scherrer's formula [33,35] . The average particle sizes of CdS : Mn nanoparticles synthesized in our study are smaller than that calculated by Patel et al [26] , Gadalla et al [1] , and Venkatesu et al [29] .…”

“…element. This means that the particle size, as calculated by using the effective mass approximation [33] , decreases and the energy gap, as found out by using the Planck's quantum theory of radiation [33−35] , increases as the Mn composition increases. The equation of the energy of a photon, E = hv was used to calculate the energy gap of the semiconductor nanoparticles.…”

“…Mn-doped CdS nanoparticles have been synthesized by a very simple method at room temperature under nitrogen atmosphere. MnCl 2 was added to cadmium acetate [Cd(CH 3 COO) 2 ] and a similar procedure was followed as that used to synthesize undoped CdS nanoparticles in our previous study [33] . Cadmium acetate taken in the reaction vessel was stirred using a magnetic stirrer.…”