The effect of static and modulated uniaxial constraint on impurity band conduction in p-type germanium

Abstract

Transport property measurements on p-type germanium, doped to be in the intermediate concentration region (1016 < NA < 1018 cm−3), were performed in the temperature range of 1.6–77 K under static (up to 337 MPa) and modulated (2.4 on 180 MPa) uniaxial compression. To elucidate the conduction mechanisms in this region the position of the Fermi level is calculated as a function of temperature and uniaxial stress and correlated to the variation of the measured transport properties. The analyses indicate an Anderson type metallic conduction, characteristic of random, amorphous systems, while the Fermi level is in the impurity band. Mott type metallic conduction, characteristic to periodic systems, determines the transport properties as the Fermi level moves out of the impurity band.