Peculiarities of charge carriers transport in submicron Si-Ge whiskers

Abstract

The paper presents an analysis of impact of charge carriers transport mechanisms on the thermoelectric properties of Si-Ge submicron whiskers. Based on the resistance temperature dependences the value of activation energy for conduction submicron designs was estimated and compared with the ones for micron-scale crystals. It is shown that the activation energy of ground state ε1 of boron impurity for the Si-Ge whiskers with a diameter of 200 nm is 29.6 meV, which is typical for the bulk materials, whereas ε₂ was 3.2 meV. It is suggested that the unusual high value of ε₂ caused by inhomogeneous stress at the interface between the core and nanoporous shell of the submicron whisker due to their lattice mismatch. This effect can be used to create gauges with a thermoelectric principle of operation for cryogenic temperatures.