Magnetoresistance and variable range hopping conductivity in n-CuInSe2

Variable range hopping conduction of Mott type is observed in n-type CuInSe2 in two temperature ranges. These are below 20 K and the other, above this temperature, up to 45 K, that have different values of the parameters ρo and To in the relation ρ = ρo exp [To/T]S. This type of conduction is also found at different fixed magnetic field up to 35 T. The temperature and magnetic field dependence of the magnetoresistance in both weak and strong field regimes are analyzed in the framework of the Efros and Shklovskii model. The observed departure of the hopping parameters at low temperatures from the expected theoretical prediction is explained as due to the presence of negative magnetoresistance at lower fields and the effect of saturation of the positive magnetoresistance at higher fields.