Center for Functional Nanomaterials Seminar

Quasi-one-dimensional semiconductor nanowires have shown great promise for applications in electronic, optoelectronic, and chemical sensing devices. Electronic transport in nanowires is confined to one spatial dimension which obscures the distinction between surface and bulk. Consequently, the properties of nanowire surfaces are intimately tied to the operation and performance of nanowire-based devices. Furthermore, due to the one-dimensional nature of a nanowire, no classical conducting paths exist that do not feel local perturbations from charges at the surface, positioning nanowires as ideal materials for charge-based detection and manipulation of adsorbates. InAs nanowires present an excellent system in which to study these phenomena due to their high electron mobility, native surface accumulation layer, and strong confinement effects. By analyzing the transport properties of InAs nanowire field-effect transistors, we develop a time-dependent model to accurately describe the observed behavior. The model is adapted to describe the chemical sensor response to ethanol. We identify a new regime of highly sensitive chemical sensing unique to nanowires based on a local gating effect from individual dipoles where concentrations as low as 10 ppb are detected at room temperature. This also leads to a novel transport-based method of determining adsorption isotherms.