NIRT: Properties and Applications of Deformed Nanotubes

Stanford University, Stanford CA

Investigators

Abstract

This proposal was received in response to Nanoscale Science and Engineering initiative, NSF 01-157, category NIRT. Because of their extraordinary properties, carbon nanotubes (CNT) in general have been extensively studied. Local deformations of CNT's appear to exhibit combined electrical, mechanical, thermal and even optical properties that offer particularly intriguing promise for studying physical effects at the nm scale and for novel sensors and other devices. A team with the requisite diverse backgrounds and capabilities has been formed to exploit these new opportunities. One core proposed activity is the modeling of deformed carbon nanotubes and other nanostructures (e.g. silicon nanowires) using atomic-scale simulation methods ranging from classical interatomic potential to tight-binding, ab-initio quantum simulation, and electronic and thermal conductance analysis. Quasi-static and molecular-dynamics methods will be used to study deformation processes as well as the indenting of polymer films using a CNT. The electronic conductance of deformed nanotubes will be investigated using Kubo and Landauer methods with self-consistent quantum simulations. Complementing the modeling activity will be experimental verification of the modeling results with two eventual applications in mind: 1) Nanoscale force and thermal sensors based on a nanotube bent in the shape of a hairpin. Such a device might allow temperature distributions to be mapped with a spatial resolution as fine as 10nm and also be able to respond to fast molecular dynamic force signals, and 2) A 'turnstile' electron emitter that employs the deformity in the shank of a nanotube to produce local band bending to control the transport of single electrons to the tip for field-assisted photoemission. Such a device would have significant impact on electron beam nanolithography through the elimination of shot noise and also on ultrahigh speed (100GHz) analog-to-digital conversion.