Semiconductor-to-metal transition in nanocomposites of wide bandgap oxide semiconductors

Abstract

The semiconductor-to-metal transition (SMT) is reported in nanocomposite films of wide bandgap semiconducting oxides. This study offers insight into the existing models of temperature-dependent charge transport by tailoring the defects induced disorder into the lattice by swift heavy ions irradiation. The structural studies show the presence of both cadmium oxide and zinc oxides phases and confirm the nanocomposite nature of films. Temperature-dependent charge transport properties of the nanocomposite films were studied by carrying out four-probe resistivity measurements in the wide temperature range of 35–300 K. Here, the swift heavy ions irradiated films demonstrated the tuning of SMT phenomena and its transition temperature upon increasing fluence of irradiation. These irradiation effects are discussed in terms of irradiation-induced defects/disorders into the lattice. The change in the nature of temperature-dependent resistivity in pristine and irradiated films has been envisaged with a quantitative fit of experimental data by invoking quantum correction to conductivity (QCC). Our results are consistent with QCC model, which essentially depends on weak localization and renormalized electron-electron interactions. Thus, this work extends the validity of the weak localization model to composite systems.