Hopping and correlated hopping studies of p-Ge at large uniaxial stresses and high magnetic fields

Abstract

Abstract The resistivity of p-Ge with different acceptor concentrations N A has been measured at helium temperatures, at high stresses, and longitudinal and high magnetic fields. The ranges were: 15 K > T > 4.2 K, 1015 cm−3 < N A < 4 × 1016 cm−3, H < 8 T, tensile stresses up to 6 × 107 Pa and compressive stress up to 6 × 108 Pa. All the data are in the regime of hopping transport. The data is conveniently presented in terms of the activation energy e3, and the pre-exponential ρ3. The main experimental features are as follows. The activation energy plotted against uniaxial stress X exhibits a peak for both compressive and tensile stress (although tensile stress was not large enough to observe the peak clearly). Around the stress where this peak occurs, the pre-exponential ρ3 begins to increase rather rapidly. Magnetic fields reduce the peak for compressive stress, and enhance the peak for tensile stress. At very high compressive stresses ρ3 decreases with stress. For high concentrations, e3 also decreases ...