Galvanomagnetic and optical properties of chromium doped PbTe

• Behavior of PbTe(Cr) is analyzed by galvanomagnetic and far-infrared measurements.
• Two local modes of Cr corresponding to impurity atoms in different valence states.
• Existence of plasmon-ionized impurity–phonon coupling in the PbTe(Cr).
• We compute Fermi level vs. temperature and confirm its stabilization by experiment.
• We determine that n-type PbTe(Cr) crystals has persistent conductivity.

Behavior of PbTe samples doped with different amount of Cr, prepared by two methods of synthesis is analyzed using galvanomagnetic measurements and far-infrared spectroscopy. The far-infrared reflectivity spectra of PbTe(Cr) alloys were measured in the 50–650 cm−1 spectral range at different temperatures and analyzed using a numerical fitting procedure based on the plasmon–phonon interaction model. The two local Cr modes at about 260 cm−1 and 480 cm−1 together with the strong plasmon–phonon coupling are observed. The persistent photoconductivity is registered. Using results of galvanomagnetic measurements the carrier concentrations is determined and hence we obtained the Fermi level temperature dependence.

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