Electron transport in heavily doped amorphous SnO 2 near metal–insulator transition

Abstract

The metal–insulator transition (MIT) in amorphous SiO x thin films driven by heavily doping with native oxygen vacancies has been investigated. We have found that an amorphous semiconductor may be doped during growth process up to the level where continuous MIT occurs. The temperature dependence of the resistivity of the films is defined by the deposition conditions. In metallic samples the resistivity is temperature independent, while in the critical region of the metal–insulator transition (MIT) it obeys the power-law with experimental value of 0.96 for the critical exponent. In the insulating side of the transition electrical conductivity has an exponential temperature dependence. A possible mechanism is proposed to explain the temperature dependence of conductivity in amorphous semiconductors on the insulating side of the MIT.