Conductivity mechanisms in ZnS0.5Se0.5

Low- and high-field dc conductivity measurements have been made on highly compensated as-grown ZnS0.5Se0.5 crystals in the temperature range 65–430 K. In the low-temperature range up to 220 K, where conductivity is low and varies by about 20%, it is impossible to distinguish from fit to the data between thermal activation and variable range hopping in the impurity band near the Fermi level. The high-temperature conductivity data suggest localized state conduction. A possible mechanism for localization is suggested to be small-polaron hopping.