This article is cited in 4 papers

Electronic and optical properties of semiconductors

Features of reflection spectra of single crystals of Bi$_2$Te$_3$–Sb$_2$Te$_3$ solid solutions in the region of plasma effects

N. P. Stepanov, A. A. Kalashnicov

Zabaikalsky State Humanitarian and Pedagogical University named after N. Tcherneschevsky

Abstract: Reflectance spectra of single crystals of Bi$_2$Te$_3$–Sb$_2$Te$_3$ solid solutions containing 0, 10, 25, 40, 50, 60, 65, 70, 80, 90, 99.5, and 100 mol% of Sb$_2$Te$_3$ have been studied in the range of 400–4000 cm$^{-1}$ at the temperature $T$ = 291 K and with orientation of the vector of the electric-field strength E perpendicular to the trigonal axis of the crystal $C_3$ $(\mathbf{E}\perp C_3)$. The shape of the spectra is characteristic of plasma reflection; the spectra include the features in the range 1250–3000 cm$^{-1}$ corresponding to the optical band gap $E_{g{\mathrm{opt}}}$. The features become more pronounced as the content of Bi$_2$Te$_3$ is increased to 80 mol% in the composition of the Bi$_2$Te$_3$–Sb$_2$Te$_3$ solid solution. A further increase in the content of Sb$_2$Te$_3$ is accompanied by discontinuities in the functional dependences of the parameters characterizing the plasma oscillations of free charge carriers on the solid-solution composition and also by a sharp increase in $E_{g{\mathrm{opt}}}$.

Received: 02.02.2010
Accepted: 12.02.2010

 English version: Semiconductors, 2010, 44:9, 1129–1133

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