TEMPERATURE AND PRESSURE DEPENDENCES OF GALVANOMAGNETIC PROPERTIES OF PBTE(CR) SOLID-SOLUTIONS

The temperature dependences of the carrier density and mobility, and of the electrical resistivity of PbTe(Cr) single crystals with chromium concentrations in the range 0.2 less-than-or-similar-to C(Cr) less-than-or-similar-to 0.4 at. % were investigated. It was found that the electron density n in samples with a stabilized position of the Fermi level (E(f) - E(c) almost-equal-to 100 meV at T = 4.2 K) decreased on increase in temperature, indicating a shift of the Fermi level downward on the energy scale, whereas the temperature dependence of the mobility obeyed mu proportional-to T-1. Studies of galvanomagnetic and oscillatory effects under hydrostatic pressures showed that the electron density increased from n almost-equal-to 1.2 x 10(19) cm-3 (P = 1 bar) to n almost-equal-to 2.2 x 10(19) cm-3 (P = 26 kbar). The relative shifts of the edges of the conduction and valence bands and of the Fermi level in PbTe(Cr) under pressure and due to variation of temperature were plotted. It was found that the Fermi level remained practically fixed relative to the middle of the band gap. Such diagrams had been obtained earlier for PbTe(In) and Pb(1-x)Sn(x) Te(In). The similarity of changes in the energy spectra of PbTe(Cr) and PbTe(In) suggested that the impurity level stabilizing the Fermi level position was not due to isolated In or Cr atoms, but due to some impurity atom + lattice defect complexes.