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Abstract:

We present magnetotransport results for strongly coupled InAs/GaSb superlattices. The low effective mass of carriers in the InAs/GaSb superlattice allows the study of the transport processes at fields above the magnetophonon condition, where the cyclotron spacing homega(c) is greater than the LO phonon energy homega(LO). Magnetotransport results display Stark Cyclotron resonance and the Magnetophonon effect. Resonant tunnelling features change dramatically above the magnetophonon condition and suggest the superlattice undergoes formation of ordered electric field domain states linked to the observation of LO phonon mediated tunnelling. (C) 2003 Elsevier B.V. All rights reserved.

Abstract:

We report a comparative study on gas and liquid phase oxidative treatments of SWNTs, using a HiPCO produced raw material with a broad distribution of nanotube diameters. The effects of these two processes were correlated using absorption and Raman spectroscopy (radial breathing and G modes) and TEM. We conclude that liquid phase oxidation is a continuous diameter-selective process eliminating narrower SWNTs through oxidizing sidewalls of SWNTs. Gas phase oxidation is a more discrete process requiring high activation energy for diameter-selective purification. Unlike liquid phase oxidation the gas phase process preferentially oxidizes SWNTs without introducing sidewall defects. © 2003 Elsevier B.V. All rights reserved.

Abstract:

Coupled nanostructures have been developed in the InAs/InSb/GaSb materials system in order to extend the emission wavelength further into the infrared, beyond 2 mum. The samples studied consist of a single narrow InAs quantum well grown below a layer of InSb quantum dots in a GaSb matrix, in which the coupling has been altered by changing the thickness of a GaSb spacer layer. The overall transition energy of the combined dot-well system is generally reduced with respect to the dots and well only but the dependence on spacer thickness is more complex than that expected from a simple envelope function model. (C) 2003 Elsevier B.V. All rights reserved.

Abstract:

A clear understanding of the interactions between the building blocks of self-assembled molecular materials is essential for rational design of functional nanostructures. Intermolecular interactions have been investigated for three different classes of fullerenes in single-walled carbon nanotubes (SWNTs); van der Waals molecule - molecule and molecule - SWNT interactions control the geometry of the molecular arrays inside nanotubes; electrostatic intermolecular forces influence the alignment of polar endohedral fullerenes M@C82; and hydrogen bonding between functionalised fullerenes has a significant effect on the selectivity of insertion of functionalised fullerenes into SWNTs.

Abstract:

The properties of InSb quantum dots grown by metal organic vapour phase epitaxy are summarised as deduced from photoluminescence, magneto-photoluminescence, and far-infrared modulated photoluminescence experiments. A technique is described for shifting the emission of these dots to lower energy by coupling them with a narrow InAs quantum well, leading to the demonstration of electroluminescence at similar to 2.3 mum. (C) 2003 Elsevier B.V. All rights reserved.