(98e) Nanoelectrode Sensor Devices

A fundamental interest in Nanotechnology is the potential to take advantage of the unique properties of matter at the nanoscale, including the importance of electron tunneling. We present a novel approach to nanosensors based on tunneling spectroscopy in nanofabricated nanoelectrode devices. Using advanced reaction engineering capabilities based on selective area atomic layer deposition with in-situ electrical feedback, we prepare nanoelectrode junctions that are sensitive to molecular adsorption down to the single molecule level. Real time adsorption data are demonstrated by monitoring the tunneling current during exposure to a vapor sample. The electrical data show step-like features that are associated with individual molecular adsorption events. Molecular transport based on electric field enhanced surface diffusion is used to analyze the adsorption data and successfully captures the experimental trends. Inelastic electron tunneling spectroscopy is used to characterize the vibrational frequencies of the trapped molecule, and the successful spectroscopy is confirmed using isotopic substitution. Reversible adsorption/desorption and spectroscopy are demonstrated, showing the essential characteristics of an ideal sensor. The extension to massively parallel device arrays is demonstrated by adsorption in parallel devices. Lastly, the composition and structure of the nanoelectrodes are characterized and challenges for integration of the nanoelectrode devices into practical sensors are discussed.