HIGH-FIELD POSITIVE MAGNETORESISTANCE IN THE VARIABLE-RANGE-HOPPING REGIME IN N-TYPE CUINSE2

Electrical conduction by the variable range hopping mechanism of Mott type is observed in n-type CuInSe2 over a wide temperature range up to about 50 K. A detailed study of the field dependence up to 15 T of the localization length xi and T-0 is made at different temperatures. The increase of xi with B at lower values is consistent with the magnetic field induced delocalization effect whereas at higher values it decreases due to the shrinkage of the wave functions of the impurity states. The variation of experimental T-0 with B shows a similar trend as predicted by the theory but its magnitude is much smaller. This is attributed to the increase in the dielectric constant due to correlation effects not taken into account in the theoretical expression for the density of states.