Offset Charge Distribution in Nanocluster-Based Single-Electron Tunneling Devices

We systematically investigated the offset charges in the single electron tunneling spectra of Au-cluster-based double tunnel junction system using scanning tunneling microscope. Au-clusters / alkanedithiol / Au(111) substrates, where the size of clusters is tunable (1 - 3 nm in diameter) by the amount of Au deposition with small standard deviation ( < 0.2 nm), were used. Statistical analysis shows that the offset charges distribute around 0 and the standard deviation of the distribution increases with increasing cluster size, which leads to the breakdown of the charge neutrality of the clusters.