Carrier injection and transport in arrays of monolayer-protected gold nanocrystals

We report on fabrication and electrical characterization of self-assembled 1.7 nm diameter gold nanocrystal (NC) array devices. Electrochemical data for surface-immobilized NCs reveal quantized charging effects indicating that the NCs are discrete entities with characteristic charging energies governed by their small capacitances (approx 0.3 aF). Self-assembled NC array devices show activated transport from 70-200 K (Ea approx 110 meV), consistent with sub-aF individual NC capacitances. At low temperatures, current suppression is observed below a threshold voltage (VT), again indicating that charging of the individual NCs dominates the transport. Scaling behavior of the current above VT indicates that the dimensionality of the transport network is > 2D, consistent with the NC array preparation method. Thus, the unique characteristics of individual NCs are not compromised during device fabrication, thereby offering the possibility to exploit these 'artificial atoms' in solid-state device formats.