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X-RAY ABSORPTION NEAR EDGE STRUCTURE OF As2Se3 AND As4Se4 THIN AMORPHOUS FILMS

M. Popescu1, F. Sava1,* , N. Aldea2, Xie Yaning3, Hu Tiandou3, Liu Tao3, M. Leonovici4

Affiliation

  1. National Institute of Materials Physics, R-77125 Bucharest-Magurele, P.O. Box MG. 7, Romania
  2. National Institute of R&D of Isotopic and Molecular Technologies, P.O. Box. 700, Cluj-Napoca, RO-400293 Romania
  3. Beijing Synchrotron Radiation Facilities of Beijing Electron Position Collider, Coordination Laboratory of National Center for Nanoscience and Nanotechnology, Beijing, P. R. of China
  4. University of Bucharest, Faculty of Physics, P.O. Box MG. 11, 77125 Bucharest- Magurele, Romania

Abstract

X-ray absorption spectroscopy has been used to get information on the structure of chalcogenide glasses. The data analysis was focused on the near edge X-ray absorption spectrum. The experimental As and Se K-edge absorption spectra of thin films of As2Se3 and As4Se4 have been measured in Beijing synchrotron at the beam line, using a double crystal monochromator with Si (111) crystals. The near-edge absorption curves were resolved in two components: the strong white line at the energy threshold and the first oscillatory part following the white line at approximately 7-8 eV above the K-edge, which undergoes changes in shape and position as a function of the modifications in the atomic structure induced by the change of composition. The XANES characteristic for the two types of films allows to conclude that the local disorder around As and Se is different. The non-stoichiometric composition, As4Se4, exhibits more disorder than the stoichiometric one..

Keywords

XANES, As2Se3, As4Se4, Atomic scale structure, Disorder.

Submitted at: May 21, 2005
Accepted at: July 21, 2005

Citation

M. Popescu, F. Sava, N. Aldea, Xie Yaning, Hu Tiandou, Liu Tao, M. Leonovici, X-RAY ABSORPTION NEAR EDGE STRUCTURE OF As2Se3 AND As4Se4 THIN AMORPHOUS FILMS, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 4, pp. 1801-1806 (2005)