Diode Effect in Asymmetric Double Tunnel Barriers with Single Metal Nanoclusters

Asymmetric double tunnel barriers with the center electrode being a metal cluster in the quantum regime are studied. The zero dimensionality of the clusters used and the associated quantized energy spectra are manifest in well-defined steps in the current voltage characteristic (IVC). Record high current rectification ratios of 10000 for tunneling through such clusters are demonstrated at room temperature. We are able to account for all of the experimentally observed features by modeling our double barrier structures using a combination of discrete states and charging effects for tunneling through quantum dots.