Abstract
The electrical resistivity, Hall coefficient, and weak-field magnetoresistance of homogeneous single crystals of -type Ge have been measured. The samples were either Al doped or undoped, and had exhaustion carrier concentrations from 1.3× to 8.2× . The electrical resistivity and Hall coefficient were measured from 4.2 to 300 K. Impurity-band conduction was observed at the lower temperatures. The Hall mobility from 150 to 300 K had a temperature dependence which indicates that intravalley acoustic-mode scattering is the dominant scattering mechanism in this temperature range. From a consideration of the selection rules and this Hall-mobility temperature dependence, we conclude that the symmetry of the conduction-band minima is rather than . The weak-field magnetoresistance of Ge, which was measured at 77.4 K and at three other stable temperatures (43.6, 194.5, and 299.5 K), was found to be much smaller than the magnetoresistance of Ge and Sn. The magnetoresistance coefficients , , and were obtained from these measurements and found to satisfy the symmetry relations , . This result confirms the theoretical prediction that -type Ge is a many-valley semiconductor with constant-energy spheroids in the directions. The anisotropy parameter was between 1.51 and 1.78 at 77 K. Inhomogeneous samples showed anomalies in the Hall mobilities and in the magnetoresistances.
- Received 21 January 1972
DOI:https://doi.org/10.1103/PhysRevB.6.442
©1972 American Physical Society