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Combined method of spectroscopic ellipsometry and photometry as an efficient tool for the optical characterisation of chalcogenide thin films

D. FRANTA1, D. NEČAS1, I. OHLÍDAL1,* , M. HRDLIČKA2, M. PAVLIŠTA2, M. FRUMAR2, M. OHLÍDAL3

Affiliation

  1. Department of Physical Electronics, Faculty of Science, Masaryk University, Kotl´aˇrsk´a 2, 611 37 Brno, Czech Republic
  2. Department of General and Inorganic Chemistry, University of Pardubice, n´am. ˇCs. Legi´ı 565, 53210 Pardubice, Czech Republic
  3. Institute of Physical Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Technick´a 2, 61669 Brno, Czech Republic

Abstract

The optical characterisation of the As33Se67 and Ge2Sb2Te5 chalcogenide thin films is carried out using the combined method of VASE and SR. This method permits to determine both structural and dispersion parameters describing the thin films exhibiting various defects. The structural model is based on including roughness, overlayers and thickness nonuniformity. The dispersion models are based on parametrisation of the joint density of states. These models, unlike the classical models derived from the Lorentz oscillator model, can describe finite bands which allows to introduce a parameter proportional to the density of electrons. It is shown that this method enables to investigate quantitatively changes in the electronic structure of the materials caused by phase transitions which is demonstrated on the Ge2Sb2Te5. It is shown that the combined method with including true structural and dispersion models is a powerful tool for the optical characterisation of thin films exhibiting disordered structure..

Keywords

Ellipsometry, Photometry, Chalcogenige, Thin film.

Submitted at: July 5, 2009
Accepted at: Dec. 10, 2009

Citation

D. FRANTA, D. NEČAS, I. OHLÍDAL, M. HRDLIČKA, M. PAVLIŠTA, M. FRUMAR, M. OHLÍDAL, Combined method of spectroscopic ellipsometry and photometry as an efficient tool for the optical characterisation of chalcogenide thin films, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 12, pp. 1891-1898 (2009)