Professor Robert Taylor

Abstract:

We have registered the position and wavelength of a single InGaAs quantum dot using an innovative cryogenic laser lithography technique. This approach provides accurate marking of the location of self-organized dots and is particularly important for realizing any solid-state cavity quantum electrodynamics scheme where the overlap of the spectral and spatial characteristics of an emitter and a cavity is essential. We demonstrate progress in two key areas towards efficient single quantum dot photonic device implementation. Firstly, we show the registration and reacquisition of a single quantum dot with 50 and 150 nm accuracy, respectively. Secondly, we present data on the successful fabrication of a photonic crystal L3 cavity following the registration process.

Abstract:

We present a study of the effect of externally applied vertical electric field on the optical properties of single InGaN/GaN quantum dots via microphotoluminescence spectroscopy. This is achieved by incorporating the quantum dot layer in the intrinsic region of a p-i-n diode structure. We observe a large blue energy shift of ∼60 meV, which is explained by the partial compensation of the internal piezoelectric field. The energy shift dependence on the applied field allows the determination of the vertical component of the permanent dipole and the polarizability. We also present theoretical modelling of our results based on atomistic semi-empirical tight-binding simulations. A good quantitative agreement between the experiment and the theory is found. © 2007 Elsevier Ltd. All rights reserved.

Abstract:

We present a study of the effect of externally applied vertical electric field on the optical properties of single InGaN/GaN quantum dots via microphotoluminescence spectroscopy. This is achieved by incorporating the quantum dot layer in the intrinsic region of a p-i-n diode structure. We observe a large blue energy shift of similar to 60 meV, which is explained by the partial compensation of the internal piezoelectric field. The energy shift dependence on the applied field allows the determination of the vertical component of the permanent dipole and the polarizability. We also present theoretical modelling of our results based on atomistic semi-empirical tight-binding simulations. A good quantitative agreement between the experiment and the theory is found. (C) 2007 Elsevier Ltd. All rights reserved.

Abstract:

Using a modified droplet epitaxy approach in metal-organic vapour phase epitaxy (MOVPE), we have grown InGaN quantum dots (QDs) on top of a 20-period AlN/GaN distributed Bragg reflector (DBR). The QDs were located at the centre of a ca. 182 nm GaN layer. To complete the cavity a three-period SiOx/SiNx DBR was deposited onto the GaN surface. Despite the evolution of roughness during the growth of the AlN/GaN DBR, due to cracking of the AlN layers, a cavity mode was observed, with a quality-factor of ∼50. Enhanced single QD emission was observed in micro-photoluminescence studies of the sample, and photon-correlation spectra provided evidence for single photon emission. © 2007 Elsevier B.V. All rights reserved.

Abstract:

Using a modified droplet epitaxy approach in metal-organic vapour phase epitaxy (MOVPE), we have grown InGaN quantum dots (QDs) on top of a 20-period AlN/GaN distributed Bragg reflector (DBR). The QDs were located at the centre ofa ca. 182 nm GaN layer. To complete the cavity a three-period SiOx/SiNx DBR was deposited onto the GaN surface. Despite the evolution of roughness during the growth of the AlN/GaN DBR. due to cracking of the AlN layers, a cavity mode was observed, with a quality-factor of similar to 50. Enhanced single QD emission was observed in micro-photoluminescence studies of the sample, and photon-correlation spectra provided evidence for single photon emission. (C) 2007 Elsevier B.V. All rights reserved.