Alan R. Hopkins

Single-ion adsorption and switching in carbon nanotubes

Single-ion detection has, for many years, been the domain of large devices such as the Geiger counter, and studies on interactions of ionized gasses with materials have been limited to large systems. To date, there have been no reports on single gaseous ion interaction with microelectronic devices, and single neutral atom detection techniques have shown only small, barely detectable responses. Here we report the observation of single gaseous ion adsorption on individual carbon nanotubes (CNTs), which, because of the severely restricted one-dimensional current path, experience discrete, quantized resistance increases of over two orders of magnitude. Only positive ions cause changes, by the mechanism of ion potential-induced carrier depletion, which is supported by density functional and Landauer transport theory. Our observations reveal a new single-ion/CNT heterostructure with novel electronic properties, and demonstrate that as electronics are ultimately scaled towards the one-dimensional limit, atomic-scale effects become increasingly important.

Single Event Effects in Carbon Nanotube-Based Field Effect Transistors Under Energetic Particle Radiation

We present results from proton radiation experiments with carbon nanotube field effect transistors. Single event effects were observed consisting of drops in current, with very long durations (100 s of ms), and sudden, discrete switching events between quantized current levels. These studies are important for the development and understanding of advanced nano-electronic devices operating in the space radiation environment.