Professor Robert Taylor

Abstract:

A novel method for the growth of InGaN quantum dots (QDs) by metal-organic vapour phase epitaxy (MOVPE) is described. A thin InGaN epilayer is grown on a GaN buffer layer and then annealed at growth temperature in molecular nitrogen inducing QD formation. The photolummescence from the dot ensemble is bright and comparable in intensity to that from a quantum well. Micro-photoluminescence studies of these QDs reveal sharp peaks with typical line widths of similar to250 mueV at 4.2 K. Time-resolved photoluminescence suggests that the excitons in these structures have lifetimes in excess of 2 ns at 4.2 K. (C) 2003 Elsevier B.V. All rights reserved.

Abstract:

We describe a lithographic process for the fabrication of small size optical apertures, together with large alignment marks to locate the aperture position during measurements in an optical cryostat. The aperture size is chosen to isolate a small number of dots from a dense self-assembled array of InGaN dots. The pattern was exposed in a chemically-amplified resist, UVIII and transferred to the underlying aluminium layer using reactive ion etching. Micro-photoluminescence measurements show sharp spectral lines of width ∼700 μeV at 4.2 K (limited by the spectral resolution of the monochromator), confirming the isolation of a single quantum dot. © 2004 Elsevier B.V. All rights reserved.

Abstract:

By means of a 3D self-consistent numerical simulation we have calculated the effect of an externally-applied lateral electric field upon a single InGaN quantum dot. Overall, good agreement between the modeling and experimental results was observed. Modeling results support the observation that the quantum-confined Stark effect has both permanent dipole moment and polarizability components.