Electronic and structural transitions in Pb1−xGexTe:Ga alloys under pressure

The effect of pressure on electrical properties of Ga-doped n-Pb1−xGexTe alloys (x=0.06, 0.08) is studied. The pressure dependence of the activation energy of a deep Ga impurity center is obtained. It is shown that the position of the Ga level with respect to the bottom of the conduction band is virtually unchanged under pressure. Anomalies are found in the temperature and pressure dependences of the resistivity; these anomalies are apparently associated with structural phase transitions from the cubic to the rhombohedral and orthorhombic phases, respectively. The results obtained are used to construct a diagram of the modification of the energy spectrum of charge carriers in the cubic phase of the alloys investigated under pressure.