Quantum Optoelectronics

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Photoluminescence studies of exciton recombination and dephasing in single InGaN quantum dots

IEEE Transactions on Nanotechnology 3:3 (2004) 343-347

Authors:

JH Rice, JW Robinson, JD Smith, A Jarjour, RA Taylor, RA Oliver, GAD Briggs, MJ Kappers, S Yasin, CJ Humphreys

Abstract:

This paper reports on time-integrated and time-resolved microphotoluminescence (μ-PL) measurements of single InGaN quantum dots (QDs). The linewidths of the μ-PL peaks originating from single metal-organic vapor phase expitaxy-grown III/V InGaN QDs are measured, implying dephasing times of at least 5 ps. Temporal fluctuations of the QD emission energy are observed, and these are explained in terms of randomly generated local electric fields inducing a Stark shift in the optical emission of the InGaN QDs. Time-resolved measurements demonstrate that decay dynamics from single InGaN QDs are exponential in nature. Measurements of the effect of temperature upon the recombination times in individual InGaN QDs have been performed from 4 to 60 K.
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Sub-wavelength Al mask apertures for addressing individual InGaN quantum dots

Microelectronic Engineering Elsevier BV 73-74 (2004) 762-766
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Sub-wavelength Al mask apertures for addressing individual InGaN quantum dots

MICROELECTRON ENG 73-74 (2004) 762-766

Authors:

S Yasin, MN Khalid, JH Rice, RA Taylor

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 similar to700 mueV at 4.2 K (limited by the spectral resolution of the monochromator), confirming the isolation of a single quantum dot. (C) 2004 Elsevier B.V. All rights reserved.
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Temporal variation in photoluminescence from single InGaN quantum dots

Applied Physics Letters 84:20 (2004) 4110-4112

Authors:

JH Rice, JW Robinson, A Jarjour, RA Taylor, RA Oliver, G Andrew, D Briggs, MJ Kappers, CJ Humphreys

Abstract:

The optical transmissions in single III/V (InGaN) quantum dots (QD) were measured as a function of time. The temporal fluctuations in microphotoluminescence peak position and linewidth were demonstrated and attributed to spectral diffusion processes. It was found that the temporal variations originated from randomly generated local electric fields inducing a Stark shift in the optical emission peaks of the InGaN QDs. It was also demonstrated that the spectral diffusion must be considered in the study of exciton optical transitions in single nitride based QDs.
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Time-integrated and time-resolved photoluminescence studies of InGaN quantum dots

Physica Status Solidi C: Conferences 1:3 (2004) 568-572

Authors:

JW Robinson, JH Rice, A Jarjour, JD Smith, RA Taylor, RA Oliver, GAD Briggs, MJ Kappers, CJ Humphreys, S Yasin, Y Arakawa

Abstract:

We present studies of the optical transitions in InGaN quantum dots (QDs). Spatially-resolved microphotoluminescence (μ-PL) of single InGaN QDs reveals very sharp, clearly-defined peaks that are characteristic of strongly-confined carriers. Time-resolved measurements for single InGaN QDs reveal single exponential decays in contrast to non-exponential decays from the 2D wetting layer (WL) and from ensemble measurements. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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