Electronic structure and tunneling resonance spectra of nanoscopic aluminum islands

The electronic structure of nanoscopic oxide-coated aluminum islands is investigated using a tight-binding model that incorporates the geometry, chemistry and disorder of the particle. The oxide coat is found to significantly increase the volume accessible to electrons at the Fermi level. The level statistics agree with random matrix theory predictions. States near the Fermi level show pronounced clustering regardless of disorder. It is suggested that the observed clusters of tunneling resonances may have a more complex origin than if they were solely due to many-body non-equilibrium effects.