Preparation of thermally deposited Cu-x(ZnS)(1-x) thin films for optoelectronic devices

摘要

Zinc sulfide thin films have been doped with copper atoms to investigate their efficiency as transparent conductor layers. Cu-x(ZnS)(1-x) thin films were deposited on glass substrate using thermal evaporation technique by varying the Cu concentration (x = 0.01, 0.02, 0.03, 0.05, 0.10 and 0.25). The prepared thin films were characterized using XRD, FE-SEM, EDS and UV-Vis spectroscopy. The X-ray diffraction studies revealed that the films are crystalline in nature and well oriented along (111) direction with the cubic crystal structure. Crystallite size increases with increase in Cu concentration. FE-SEM studies showed that the films are homogenous and pin-hole free. All the films exhibited p-type conductivity. It was also observed that the band gap of the Cu-x(ZnS)(1-x) films vary from 3.48 eV to 2.60 eV when the copper content varies from 0 to 0.25. At a Cu concentration of x = 0.03, the hole conductivity increases to 1.9 x 10(3) S/m retaining an optical transparency of similar to 73% in the visible spectra. This combination of optical transparency and hole conductivity of Cu-x(ZnS)(1-x) thin films for such low Cu concentration is, to our knowledge, the best reported to date. (C) 2018 Elsevier B.V. All rights reserved.