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We synthesize a scandium-doped PbTe single-crystal ingot and investigate the phase and the elemental composition as well as galvanomagnetic properties of Pb1-yScyTe alloys in weak magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) upon varying the scandium content (y ≤ 0.02). We find that all investigated samples are single-phase and n-type. The distribution of scandium impurities along the axis of the ingot is estimated to be exponential. An increase of scandium impurity content leads to a monotonous growth of the free electron concentration by four orders of magnitude (approximately from 1016 cm−3 to 1020 cm−3). In heavily doped alloys (y > 0.01), the free electron concentration at the liquid-helium temperature tends to saturation, indicating the pinning of the Fermi energy by the scandium resonant impurity level located on the background of the conduction band. Using the two-band Kane and six-band Dimmock dispersion relations for IV-VI semiconductors, dependences of the Fermi energy measured from the bottom of the conduction band Ec on the scandium impurity content are calculated and the energy of the resonant scandium level is estimated to be ESc ≈ Ec + 280 meV. Diagrams of electronic structure rearrangement of Pb1-yScyTe alloys upon doping are proposed.

The effect of ytterbium impurity on the magnetic and galvanomagnetic properties of new diluted magnetic semiconductors Pb 1-x Sn x Te : Yb was investigated. Impurity-related Curie-Weiss paramagnetism was revealed. The concentration of magnetic centers and the ytterbium impurity-band occupancy as a function of impurity content were determined. The results are discussed assuming the formation of a ytterbiuminduced level under the valence-band top and a variation of the magnetic centers concentration due to changing of the mutual arrangement of the valence band, impurity level and Fermi-level position.

We synthesize an iron-doped PbTe single-crystal ingot and investigate the phase and the elemental composition as well as galvanomagnetic properties in weak magnetic fields (4.2 K≤T≤300 K, B ≤ 0.07 T) of Pb1−yFeyTe alloys upon varying the iron content, at atmospheric pressure and under hydrostatic compression up to 10 kilobars. We find an increase of iron concentration along the length of the ingot and the appearance of microscopic inclusions enriched with iron in the heavily doped samples. Lightly doped alloys are characterized by the p-type metal conductivity. An increase of the iron impurity content leads to a decrease in the free hole concentration, a stabilization of galvanomagnetic parameters, indicating the pinning of the Fermi energy by the iron resonant impurity level lying under the bottom of the valence band, and to the p-n inversion of the conductivity type. Under pressure, the free hole concentration in the sample, in which the stabilization of galvanomagnetic parameters takes place, increases by approximately a factor of four due to the flow of electrons from the valence band to the iron-induced resonant level. Using the two-band Kane and the six-band Dimmock dispersion relations, the pressure dependence of the Fermi energy is calculated. The model of the electronic structure rearrangement of Pb1−yFeyTe under pressure is proposed. The energy position and the pressure coefficient of the resonant iron impurity level are determined.

A study of phase and elemental compositions, galvanomagnetic properties (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) and Shubnikov – de Haas oscillations (T = 4.2 K, B ≤ 6.5 T) in Pb1–x–ySnxFeyTe alloys with varying concentrations of tin and iron in single-crystal ingots synthesized using the Bridgman-Stockbarger method was performed. Scanning electron microscopy and X-ray fluorescence microanalysis revealed the presence of iron enriched microscopic inclusions, and the distribution of tin and iron along the ingots was determined. An increase in the concentration of holes with increasing concentrations of tin and iron, as well as anomalous temperature dependences of the Hall coefficient, which indicates a pinning of the Fermi level at the resonant level of iron, were detected. A model of electron structure rearrangement is proposed in order to explain the experimental dependences of the hole concentration and the Fermi energy relative to the valence band top as a function of tin concentration in the alloys. The model assumes that the iron level moves from the top to the depth of the valence band as the tin concentration increases. The compositional coefficient of iron level movement relative to the edges of the energy bands with increasing tin content in Pb1–x–ySnxFeyTe alloys is determined using the two-band Kane dispersion law.