Effect of oxidation on the conductivity of nanocrystalline PbTe:In films in an alternating electric field

Temperature and frequency dependences of components of complex impedance for nanocrystalline PbTe:In films in the temperature range of 4.2–300 K and the frequency range from 20 Hz to 1 MHz have been studied. The films were deposited onto a cooled glass substrate and then annealed in an oxygen atmosphere at temperatures of 300 and 350°C. The charge-carrier transport in the studied films is controlled by charge transport over inversion channels at the surface of grains and by transitions through barriers at the grain boundaries. Parameters (resistance and capacitance) corresponding to each of above-mentioned mechanisms were determined. Dominant contribution to conductance of the film annealed at 350°C is made by inversion channels. It is shown that the transport of charge carriers over inversion channels in the region of low temperatures is realized by hopping conductivity.