Lithium Ions Intercalated into Pyrene-Functionalized Carbon Nanotubes and Their Mass Transport:  A Chemical Route to Carbon Nanotube Schottky Diode

We developed a facile chemical route by which single-walled carbon nanotube (SWNT) Schottky diodes are realized. When a bias voltage was applied to a lithium ion intercalated SWNT field effect transistor (FET) device, lithium ions intercalated between 1-pyrenmethylamine (1-PMA), and SWNTs are migrated to the drain (−) electrode to be reduced at the junction of SWNT and drain metal electrode. As a result, asymmetric work function energy levels are formed between both junctions of SWNT−drain and SWNT−source, resulting in a Schottky diode. Using scanning photoelectron microscopy (SPEM) and space-resolved X-ray photoelectron spectroscopy (XPS), the mass transport of the lithium ion was qualitatively confirmed by monitoring the population distribution of lithium along the nanotube axis from the source to drain electrodes. The highest population of lithium was observed near the drain electrode. This approach is a simple and versatile process that can be further applied for the modifications of various nanomaterial-based electronic devices.