Structure and electrophysical properties of thin-film SnO2–In2O3 heterostructures

Abstract

The structure and electrical properties of In2O3 and SnO2 oxide semiconductors and heterostructures based on them has been experimentally investigated. The films were prepared by the method of layer-by-layer deposition using the ion-beam sputtering. The transition from the two-phase film of amorphous SnO2 and In2O3 islands, formed during the layer-by-layer deposition, to a multilayer structure consisting of the amorphous SnO2 and In2O3 continuous layers occurs with an increase in the bilayer thickness. The electrophysical properties of the (SnO2/In2O3)69 heterostructures are determined by the transition from the random distribution of SnO2 and In2O3 amorphous phases to a multilayer structure and the temperature range of measurement. For all studied systems, a consistent change in the prevailing mechanism of conductivity is observed at temperatures from 77 to 300 K. In (SnO2/In2O3)69 thin films with a bilayer thickness hbl < 2.5 nm, change of the prevailing conduction mechanism takes place according to the next sequence: variable range hopping conduction over localized states near the Fermi level, hopping conduction over the nearest neighbors and hopping transfer of carriers excited into localized states near the band edges at temperatures close to room temperature.