Electrical Properties and Energy Spectrum of In-Doped Pb1-xGexTe

Effects of In-impurity on the electrical properties of an In-doped n-type Pb 1- x Ge x Te ( x =0.02) are investigated between 4.2 K and 300 K. It is found that the Hall coefficient shows the qualitatively similar anomalous behaviour to that of In-doped PbTe. But, the resistivity increased almost exponentially with increasing temperature. The phase transition is not affected by In-doping. The energy spectrum in the rhombohedral phase is studied by observing the quantum oscillations of the sound velocity at 1.5 K. It is found that the angular dependences of the observed periods are well fitted to the model which has been proved to be valid for undoped Pb 1- x Ge x Te in our previous work.