R. A. Taylor

Publications (26)15.99 Total impact

• Article: Registration of single quantum dots for solid state cavity quantum electrodynamics

  K H Lee, F. S. F. Brossard, R. A. Taylor, A. M. Green, A. J. Turberfield, D A Williams, G. A. D. Briggs
  [show abstract] [hide abstract]
  ABSTRACT: We discuss a novel technique to register the spatial and spectral characteristics of a single quantum dot using two photon absorption laser lithography. This would be useful in realizing solid state cavity quantum electrodynamics. © 2005 British Crown Copyright.
• Article: Free carrier screening in coupled asymmetric GaN quantum discs

  K H Lee, J. H. Na, S. Birner, R. A. Taylor, S. N. Yi, Y S Park, C. M. Park, T. W. Kang
  [show abstract] [hide abstract]
  ABSTRACT: We present an investigation of free-carrier screening in coupled asymmetric GaN quantum discs with embedded AlGaN barriers using time-integrated and time-resolved micro-photoluminescence measurements, supported by three-dimensional multi-band k.p computational modeling. We observe that with increasing optical excitation the carrier lifetime decreases and emission energy blue-shifts. This originates from the screening of built-in piezo- and pyroelectric fields in the quantum discs by photo-generated free-carriers. Due to non-resonant tunneling of carriers from the smaller disc to the larger disc, free carrier screening is enhanced in the larger disc. The non-resonant tunneling was found to have a significant role in samples with a thin barrier, as the screening decreased with barrier thickness (i.e. decreased tunneling). Computational modeling, was in good agreement with the experimental results.
• Source

  Available from: Stefan Birner

  Article: Two-photon excitation spectroscopy of coupled asymmetric GaN/AlGaN quantum discs

  K H Lee, S. Birner, J. H. Na, R. A. Taylor, S. N. Yi, Y S Park, C. M. Park, T. W. Kang
• Article: Time-resolved and time-integrated photoluminescence studies of coupled asymmetric GaN quantum discs embedded in AlGaN barriers

  J. H. Na, R. A. Taylor, J.H. Rice, J.W. Robinson, K H Lee, Y S Park, C. M. Park, T. W. Kang
  [show abstract] [hide abstract]
  ABSTRACT: We have investigated exciton dynamics in asymmetric GaN quantum discs embedded in AlGaN barriers with an Al content of 50% using time-integrated and time-resolved micro-photoluminescence measurements. Emission from the quantum discs emerges at lower energy than that from the GaN nanocolumns, which suggests that GaN quantum discs are strongly affected by the built-in electric field. The lifetimes of localized excitons in quantum discs were obtained. Nonlinear emission from quantum discs under high excitation power was attributed to tunneling of carriers to larger discs from smaller discs.
• Article: Accuracy of single quantum dot registration using cryogenic laser photolithography

  K H Lee, A. M. Green, F. S. F. Brossard, R. A. Taylor, D. N. Sharp, A. J. Turberfield, D A Williams, G. A. D. Briggs
  [show abstract] [hide abstract]
  ABSTRACT: We have registered the position of single InGaAs quantum dots using a novel cryogenic laser photolithography technique. This would be useful in realizing solid state cavity quantum electrodynamics. By fabricating metal alignment markers around the quantum dot, it was registered with an accuracy of 50 nm. Following the marker fabrication process we demonstrated that the same quantum dot was reacquired, with an accuracy of 150 nm. The photoluminescence spectra from the quantum dots before and after processing were identical except for a small red shift (~1 nm), probably introduced during the reactive ion etching.
• Article: Investigation of inter-valley scattering and hot phonon dynamics in GaAs quantum wells using femtosecond luminescence intensity correlation

  A.M. de Paula, R.A. Taylor, C.W.W. Bradley, A.J. Turberfield, J.F. Ryan
  [show abstract] [hide abstract]
  ABSTRACT: Photoluminescence intensity correlation measurements of GaAs quantum wells using 120 fs laser pulses show relatively slow relaxation times ⩽ 10 ps at high energy close to the L valley conduction band minimum. This value is consistent with recent measurements of the L → Γ scattering time. However, theoretical estimates show that nonequilibrium phonon effects can also give rise to slow relaxation on this timescale.
  Superlattices and Microstructures.