Measurements of discrete electronic states in a gold nanoparticle using tunnel junctions formed from self-assembled monolayers

We present results from nanometer-scale tunnel junctions fabricated using organic self-assembled monolayers (SAMs) as tunnel barriers. Single junctions have resistances consistent with tunneling through a single layer of molecules. In several devices, a gold nanoparticle nucleated within the SAM barrier. Such samples allow a sensitive test of mechanical stability - some are sufficiently stable to permit the observation of electron tunneling through individual electron-in-a-box states at low voltages and mK temperatures. We also observe anomalous transport characteristics at larger voltages, which may be due to the motion of the gold nanoparticle within the monolayer.