A temperature-dependent pre-exponential factor in Efros–Shklovskii variable range hopping conduction in p-type CuInTe2

We report on the temperature dependence of the electrical resistivity down to View the MathML source in a single crystal sample of CuInTe2 with a hole concentration at room temperature of View the MathML source. Mott type variable range hopping (VRH) conduction is observed in the temperature range from 90 to View the MathML source. A crossover to Efros–Shklovskii (ES) type VRH conduction with a temperature-dependent pre-exponential factor, i.e. ρ=ρ0Tαexp(T0/T)0.5 with α=0.18, is seen below View the MathML source. This is the first time that a crossover from Mott to ES VRH with a pre-exponential factor has been reported.