Strain effect on magnetoresistance of SiGe solid solution whiskers at low temperatures

Abstract

The aim of this paper is to study the strain-induced low-temperature behavior of Si 1− x Ge x whiskers' magnetoresistance and to estimate the prospects for the creation of physical values and sensing elements on the basis operating in strong magnetic fields. We have investigated the magnetoresistance and piezomagnetoresistance of low germanium fraction Si 1− x Ge x solid solution whiskers under the uniaxial strain (−4.3×10 −3 to +4.7×10 −4 rel. un.) at 4.2 K in a wide range of magnetic fields up to 14 T. Whiskers have been doped to the impurity concentration corresponding to both the insulator and the metal side of metal–insulator transition (MIT). It has been shown that magnetoresistance substantially depends on the doping level, the type and magnitude of samples' strain. The hopping conductivity with Δ Е 2 and Δ Е 3 activation energies at strain effect has been observed. The exponential character of magnetoresistance field dependencies has been obtained for heavily doped “metallic type” Si 1− x Ge x whiskers, while for weakly doped samples at the insulator side of MIT a square-law field dependencies of magnetoresistance have been observed at 4.2 K. A non-monotonic magnetoresistance change depending on the doping level of Si and Si 1− x Ge x whiskers in the vicinity of MIT.