Carbon Nanotube Based Molecular Electronic Devices
- PDF / 275,658 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 103 Downloads / 226 Views
MATERIALS RESEARCH
Welcome
Comments
Help
Carbon nanotube based molecular electronic devices Madhu Menona) Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055
Deepak Srivastavab) IT Modeling and Simulations Group at NAS, NASA Ames Research Center, MRJ, Mail Stop T27-A1, Moffett Field, California 94035-1000 (Received 4 February 1998; accepted 23 May 1998)
Complex three-point junctions of single-walled carbon nanotubes are proposed as building blocks of nanoscale electronic devices. Both T- and Y-junctions, made up of tubes with differing diameters and chiralities, are studied as prototypes. All the proposed complex junctions have been found to be local minima of the total energy on relaxation with a generalized tight-binding molecular dynamics scheme.
I. INTRODUCTION
The possibility of using carbon in place of silicon in the field of electronics has generated considerable enthusiasm recently. This has been made possible by the discovery of carbon nanotubes by Iijima.1 The carbon nanotubes consist of rolled-up graphene sheet with various chiralities. The electronic structure of these tubes can be either metallic or semi-conducting, depending on both the diameter and chirality, which can be uniquely determined by the chiral vector (n,m), where n and m are integers.2–7 Inspired by the unusual electronic properties of carbon nanotubes, several authors have recently investigated the possibility of connecting nanotubes of different diameter and chirality.8–13 This is because of the possibility of the junctions thus created being the building blocks of nanoscale electronic devices. The simplest way to connect two dissimilar nanotubes is found to be via the introduction of a pair of heptagon and pentagon in an otherwise perfect hexagonal graphene sheet.5 The resulting structure still contains threefold coordination for all carbon atoms forming the junction. In reality nanotubes have finite lengths and, in most cases, tend to be closed with fullerene caps. The closure introduces a small gap in the electronic structures of these tubes. Also, formation of tube junction results in considerable local strain which is relieved by the relaxation of the atoms. The relaxation is also expected to alter the electronic structure and local density of states (LDOS) of the atoms forming the junction and their neighbors. Although several theoretical models have been used in the study of nanotube heterojunctions, most of them tend to ignore the effects of relaxation altogether. In this work we explore the formations of complex 3-point heterojunctions and investigate the effects of full symmetry unconstrained relaxation on the structural a)
e-mail: [email protected] e-mail: [email protected]
b)
J. Mater. Res., Vol. 13, No. 9, Sep 1998
http://journals.cambridge.org
Downloaded: 04 Feb 2015
and electronic properties of these junctions using the generalized tight-binding molecular dynamic (GTBMD) scheme of Menon and Subbaswamy.6 The GTBMD scheme makes explicit use of the nonorthogonalit
Data Loading...
