CxByNz Nanotube based Molecular Electro-mechanical System Components
Deepak Srivastava*, a and Madhu Menonb
aIT Modeling and Simulation Group at NAS (MRJ in Code IN), NASA Ames Research Center,
MS T27A-1, Moffett Field, CA 94035-1000 bDepartment of Physics and Astronomy, University of Kentucky,
Lexington, KY 40506
Carbon and mixed CxByNz nanotubes have recently emerged as excellent candidates for nanoscale molecular electronic device components. Single wall carbon nanotubes have been identified as molecular quantum wire with good conductance over micron length scales. Nanotube heterojunctions provide rectifying switching characteristics and room-temperature field effect nanotube transistor on a SiO2 surface has been recently demonstrated.
Possibility of non-ideal quasi-one and two-dimensional nanotube heterojunctions are explored through classical and quantum molecular dynamics method. The structural stability and electronic characteristics of such junctions are studied to investigate the possibility of, easy to fabricate, nanotube hetero-junctions and devices. The structural, mechanical and electronic characterization of shallow doped carbon nanotubes with substitutional B, and N, mixed CxByNz nanotubes, and doped and undoped nanotube heterojunctions are also considered. The shallow substitutional doping significantly lowers the mechanical strength of carbon nanotubes, however, N or P character to the nanotube is imparted. Studies show that sharp carbon-heteroatomic nanotube interfaces are also possible. BN nanotubes show BN bond rotation and BB, NN bond frustration effects which limit the type of topological defects that are allowed in a BN hexagonal network. BN tube tips are non-fullerene type flat, conical, or amorphous nature that is related with the chirality of the BN nanotube considered. The mechanical strength of the heteroatomic CxByNz tubes are also investigated and found comparable to the equivalent carbon nanotubes. Quantum dynamic simulations show that heteroatomic nanotubes deform significantly different than the carbon nanotubes. The possible applications of such deformations in nano-mechanical devices will be discussed.
Overall, the studies indicate that a much wider spectrum of molecular electronic and mechanical system components are possible than the previously proposed only carbon nanotube based nanosystem components.
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