Electron transport in heavily doped amorphous SnO2 near metal-insulator transition

The metal-insulator transition (MIT) in amorphous SiOx thin films driven by heavily doping with native oxygen vacancies has been investigated. We have found that an amorphous semiconductor may he doped during growth process u p to the level where continuous MIT occurs. The temperature dependence of t he resistivity of the films is defined by the deposition conditions. In met allic samples the resistivity is temperature independent. while in the crit ical region of the metal-insulator transition (MIT) it obeys the power-law with experimental value of 0.96 for the critical exponent. In the insulatin g side of the transition electrical conductivity has an exponential tempera ture dependence. A possible mechanism is proposed to explain the temperatur e dependence of conductivity in amorphous semiconductors on the insulating side of the MIT. (C) 2001 Elsevier Science B.V. All rights reserved.