Scanning tunneling microscopy/spectroscopy of titanium dioxide nanoparticulate film on Au(1 1 1) surface

Abstract

Scanning tunneling microscopy (STM)/scanning tunneling spectroscopy (STS) of titanium dioxide nanoparticulate film on Au(1 1 1) surface is carried out yielding topography, I-V, dI/dV versus V and normalized dI/dV versus V. Isolated nanoparticles were found to exhibit semiconducting behavior with a band gap which varies from 1 to > 3.0 eV depending on the nature of substrate/nanoparticle/tip junction formation. Increase in the particulate density resulted into change in tunneling behavior from semiconducting to metallic as characterized by decrease in non-linearity in I-V curves and increase in average tunneling conductance. The results are discussed in terms of presence of adsorbed complexes on defect structure of TiO₂ surface for low coverage and availability of additional transport paths between the particles at high coverage.