FIZIKA A 17 (2008) 1 , 15-28

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CRYSTAL STRUCTURE AND OPTICAL PROPERTIES OF QUATERNARY SYSTEMS OF Bi-Sb-Te-Se

A. M. ABOU EL SOUDa, B. S. FARAGa, I. S. AHMED FARAGa, S. A. GADa and H. A. ZAYEDb
aSolid State Physics Laboratory, National Research Centre, Dokki, Cairo, Egypt
bPhysics Department, Girls College for Art, Science and Education, Shams University, Cairo, Egypt

Received 4 May 2005;   Revised manuscript received 14 June 2006
Accepted 24 January 2007  Online 25 September 2008

The quaternary systems of Bi-Sb-Te-Se were synthesized by direct fusion technique. Thin films of these compounds were prepared by thermal evaporation under vacuum of 10-4 Pa. The structural properties of these compounds in powder and thin film forms were investigated by X-ray diffraction. The optical constants (absorption coefficient and band gap) of the thin films were determined by measurements of IR absorbance in the region 2.5 - 10 mm. Analysis of the optical absorption spectra revealed the existence of two direct energy gaps.

PACS numbers: 74.70.Dd, 68.55.-a, 78.66.Li
UDC 539.216, 538.911, 535.343

Keywords: Bi-Sb-Te-Se thin films, structural properties, IR absorption, direct energy gaps

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