Variable-range hopping conductivity and magnetoresistance in n-CuGaSe2

Abstract

The low-temperature charge transport in n-CuGaSe2 was investigated in zero and nonzero magnetic field. Both the Mott as well as the Shklovskii–Efros regimes of the variable-range hopping are observed in different temperature intervals. The complete set of the parameters describing the properties of the localized electrons (the localization radius, the dielectric permeability, the width of the Coulomb gap, and the values of density of states at the Fermi level) are obtained by analysis of the conductivity in zero field, on one hand, and the positive magnetoresistance in a small field, on the other hand. The negative magnetoresistance in low fields is observed in all specimens in both hopping regimes. Moreover, it is interpreted as a result of quantum interference between different paths of the tunneling electrons in conditions of scattering by intermediate centers.