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Research Letters in Materials Science
Volume 2008, Article ID 826402, 4 pages
Research Letter

Effect of Ge Addition on the Optical Band Gap and Refractive Index of Thermally Evaporated A s 2 S e 3 Thin Films

Department of Physics, Jaypee University of Information Technology, Waknaghat, Solan, 173215 Himachal Pradesh, India

Received 18 October 2007; Accepted 26 February 2008

Academic Editor: Maria Loi

Copyright © 2008 Pankaj Sharma and S. C. Katyal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The present paper reports the effect of Ge addition on the optical band gap and refractive index of A s 2 S e 3 thin films. Thin films of A s 2 S e 3 and ( A s 2 S e 3 ) 9 0 G e 1 0 were prepared by thermal evaporation technique at base pressure 1 0 4  Pa. Optical band gap and refractive index were calculated by analyzing the transmission spectrum in the spectral range 400–1500 nm. The optical band gap decreases while the refractive index increases with the addition of Ge to A s 2 S e 3 . The decrease of optical band gap has been explained on the basis of density of states; and the increase in refractive index has been explained on the basis increase in disorder in the system.