Determination of Tm charge state in PbTe(Tm) by XANES method

A. I. Lebedev, I. A. Sluchinskaya, S. G. Nikitenko, S. G. Dorofeev

Abstract

The local environment and the charge state of Tm atoms in PbTe were studied by EXAFS and XANES techniques at the L_III absorption edge of Tm (8.648 keV). It was revealed that Tm atoms predominantly substitute for Pb atoms in PbTe and are surrounded by Te atoms at a distance of 2.99 0.02 A. Tm atoms were found to be in Tm³⁺ charge state independently of the section of the phase diagram used for Tm doping. These results are in agreement with the results of previous investigation of the Pb-Tm-Te phase diagram. Electrical studies of PbTe(Tm) with large deviation from stoichiometry revealed that the electron concentration was about one order of magnitude lower than the total Tm concentration and remained nearly constant (about 10¹⁹ cm^-3) while varying the sample composition. Reduced electrical activity of the Tm impurity in PbTe was explained by effect of selfcompensation.

Keywords: X-ray absorption spectroscopy, semiconductors, lead telluride, thulium impurity, doping

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