Variable range hopping conductivity and negative magnetoresistance in n-type InP semiconductor

The low temperature electrical conductivity behaviour of the n-type InP sample in the insulating regime of the metal–insulator transition is studied in magnetic fields. A negative magnetoresistance is observed and follows the variable range hopping mechanism of conduction. The negative magnetoresistance Δρ/ρ0 varies as f1(T)B2 in low magnetic fields and as f2(T)B in moderate fields both in agreement with the theoretical predictions based on quantum interference. The resistance follows the Efros–Shklovskii variable range hopping as ln ραT−1/2 in the presence of a Coulomb gap in the density of states.