Publication: Structural and optical properties of RF-sputtered CdTe thin films grown on CdS:O/CdS bilayers
Date
2020
Authors
Das N.K.
Farhad S.F.U.
Chakaraborty J.
Gupta A.K.S.
Dey M.
Al-Mamun M.
Matin M.A.
Amin N.
Journal Title
Journal ISSN
Volume Title
Publisher
International Journal of Renewable Energy Research
Abstract
In this work, we report the structural and optical properties of CdTe thin films on Oxygenated Cadmium Sulfide (CdS:O)/Cadmium Sulfide (CdS) bilayers using RF magnetron sputtering for different substrate temperatures (150, 200, 250, 300 and 350 �C) in Argon ambient. The XRD spectra reveal the polycrystalline nature of all the CdTe thin films with preferential cubic orientation along (111) directions. Raman Spectra show the dominant peak at 163.5 cm-1 and its overtone at 328.7 cm-1 which corresponds to the longitudinal optical (LO) phonon of CdTe. The SEM microscopy exhibits the uniform growth of CdTe films onto the entire glass substrate. Improved spectral response is observed for CdS:O layer and CdS:O/CdS bilayer in comparison with the CdS layer. The optical transmission of the CdTe films begins at the edge of 800 nm wavelength and shows interference fringe in the transmission spectra. The thickness of the deposited films and the optical constants are calculated from the fringe pattern. The thicknesses of the CdTe films are found to be increasing from 2.34 ?m to 2.82 ?m with the increasing substrate temperature i.e. from 150 to 250�C. Thereafter, the CdTe film thickness decreases to 2.24 ?m while the temperature increases further up to 350�C. The optical bandgap of the deposited CdTe films follows an increasing trend of 1.48 eV to 1.54 eV with the increase of substrate temperature 150 to 250�C after that the bandgap decreases to 1.51 eV for 350�C. Hence the obtained structural and optical properties suggest that the deposited CdTe films can be used as a suitable absorber layer for the thin film-based solar cells. � 2020, International Journal of Renewable Energy Research.
Description
Cadmium sulfide; Cadmium telluride; Crystallite size; Energy gap; Glass substrates; II-VI semiconductors; Light transmission; Magnetron sputtering; Optical constants; Optical films; Optical properties; Argon ambient; Bi-layer; Different substrates; Polycrystalline; R.F. magnetron sputtering; RF sputtering; Structural and optical properties; Substrates temperature; Thin-films; XRD spectra; Thin films