Selective-area atomic layer deposition of copper nanostructures for direct electro-optical solar energy conversion

We investigate selective-area atomic layer deposition (ALD) of copper onto nanofabricated palladium structures for plasmonic applications in electro-optic conversion devices. We examine arrays of nanofabricated tip shaped electrodes for the formation of geometrically asymmetric tunnel junctions. We find ALD growth to be sensitive to sample pretreatment, and demonstrate that UVozone treatment is effective for initiating growth. We show that nucleation density and grain evolution are important properties of growth because ALD deposited topological features are on the same scale as the nanostructures. We predict electric-field intensities within the gap region between electrodes to scale exponentially with ALD growth. We establish the basis for ALD tuning of plasmonic nanostructures.