Effects of thermal annealing on structural and optical properties of sputtered CdS thin films for photovoltaic application

Author

Islam, M.A. ; Hossain, M.S. ; Aliyu, M.M. ; Husna, J. ; Karim, M.R. ; Sopian, K. ; Amin, N.

Author_Institution

Dept. of Electr., Electron. & Syst. Eng., Univ. Kebangsaan Malaysia, Bangi, Malaysia

fYear

2012

fDate

3-8 June 2012

Abstract

The structural and optical properties of annealed CdS are studied in this work. The CdS films are deposited on ITO coated glasses by sputtering at different substrate temperatures and subsequently annealed in an O₂/N₂ ambient. It has been observed from XRD diffraction that the films show a trend of conversion from poly crystalline to amorphous or mixed phases after annealing. The films fabricated at room temperature (RT) have been found in complete amorphous form. The surface roughness of the films drastically increased due to thermal annealing observed from AFM images. Optical properties of the films were observed using UV-Vis spectrometer and band gaps of the films were found in the range of 2.80 to 3.08 eV. The annealed films exhibited the blue shift in the direct allowed transition energy band gaps, possibly due to the oxygen incorporation during annealing suggesting the transformation to CdS:O films.

Keywords

II-VI semiconductors; X-ray diffraction; amorphous semiconductors; annealing; atomic force microscopy; cadmium compounds; mixing; optical constants; oxygen; semiconductor growth; semiconductor thin films; solid-state phase transformations; sputter deposition; surface roughness; ultraviolet spectra; visible spectra; wide band gap semiconductors; AFM; CdS:O; ITO-SiO₂; UV-visible spectrometry; X-ray diffraction; XRD; atomic force microscopy; indium tin oxide-coated glasses; optical properties; oxygen incorporation; phase mixing; photovoltaic application; polycrystalline-amorphous phase transformation; sputter deposition; structural properties; surface roughness; temperature 293 K to 298 K; thermal annealing; thin films; transition energy band gap; Annealing; Optical films; Photonic band gap; Photovoltaic cells; Rough surfaces; Substrates; band gap; cadmium sulphide; sputtering; thermal annealing; thin film;

fLanguage

English

Publisher

ieee

Conference_Titel

Photovoltaic Specialists Conference (PVSC), 2012 38th IEEE

Conference_Location

Austin, TX

ISSN

0160-8371

Print_ISBN

978-1-4673-0064-3

Type

conf

DOI

10.1109/PVSC.2012.6317589

Filename

6317589