Professor Robert Taylor

Abstract:

We present a study of the time-integrated and time-resolved photoluminescence properties of single-InGaN/GaN quantum dots (QDs) using two-photon spectroscopy. Two samples containing QDs produced by different growth techniques are examined. We find that two-photon excitation results in the suppression of the emission from the underlying quantum well to which the QDs are coupled and yet relatively strong QD emission is observed. This effect is explained in terms of the enhancement of two-photon absorption in QDs due to the full confinement of carriers. Furthermore, evidence of the presence of excited states is revealed from the two-photon photoluminescence excitation spectra presented in the study. © 2006 Elsevier B.V. All rights reserved.

Abstract:

We present a study of the time-integrated and time-resolved photo luminescence properties of single-InGaN/GaN quantum dots (QDs) using two-photon spectroscopy. Two samples containing QDs produced by different growth techniques are examined. We find that two-photon excitation results in the suppression of the emission from the underlying quantum well to which the QDs are coupled and yet relatively strong QD emission is observed. This effect is explained in terms of the enhancement of two-photon absorption in QDs due to the full confinement of carriers. Furthermore, evidence of the presence of excited states is revealed from the two-photon photoluminescence excitation spectra presented in the study. (c) 2006 Elsevier B.V. All rights reserved.

Abstract:

Magnesium-doped GaN nanorods were grown on Si(111) substrates by plasma-assisted molecular-beam epitaxy. Time-integrated and time-resolved photoluminescence measurements were carried out to study the optical transitions. Two emission lines corresponding to blue emission at about 3.26 and 3.18 eV, with their corresponding phonon replicas, were observed. These peaks are attributed to conduction band to shallow acceptor transitions and to defects associated with column/substrate interface-shallow Mg acceptor complexes, respectively. © 2006 IOP Publishing Ltd.