OPTICAL PROPERTIES OF In2S3 THIN FILMS DEPOSITED
BY VACUUM THERMAL EVAPORATION TECHNIQUE
A. Timoumi*, H. Bouzouita, M. Kanzari, B. Rezig
Photovoltaic and semiconductor materials laboratory
National Engineering School of Tunis, Belvedere PO Box 37, 1002 Tunis, Tunisia
* Corresponding author. E-mail: email@example.com
Received: 10 April 2004, revised version accepted: 13 May 2005
Indium sulphide thin films were synthesized and grown by single source vacuum thermal evaporation technique. Both the as-grown and annealed films were studied. In this work, we have used transmittance and reflectance measurements to study the optical properties of In2S3. The substrate temperature was fixed at 513 K. The optical constants of the deposited films were obtained from the analysis recorded transmission and reflectance spectral data over the wavelength range 300-1800nm. The transmission coefficient (T) reached 85% when the films were annealed at various temperatures under vacuum atmosphere. On the other hand, these spectra show that for an approximately same thickness (e » 1m m) and a refractive index about 2.60. Analysis of the optical absorption data for as-deposited films revealed an optical direct transition with the estimation of the corresponding band gap value. Band to band transitions which give rise to the optical absorption in the visible region of the spectrum may be interpreted in terms of direct allowed transition with the band gap in the range of 2.00-2.20eV. All direct and indirect optical gaps were determined for different conditions.
Keywords: Thermal evaporation; Optical analysis; Indium Sulphide; Annealing conditions.