Professor Robert Taylor

Abstract:

We have investigated exciton localization in binary GaN nanorods using micro- and time-resolved photoluminescence measurements. The temperature dependence of the photoluminescence has been measured, and several phonon replicas have been observed at the lower energy side of the exciton bound to basal stacking faults (I 1). By analyzing the Huang-Rhys parameters as a function of temperature, deduced from the phonon replica intensities, we have found that the excitons are strongly localized in the lower energy tails. The lifetimes of the I 1 and I 2 transitions were measured to be < 100 ps due to enhanced surface recombination. PACS: 78.47.+p, 78.55.-m, 78.55.Cr, 78.66.-w, 78.66.Fd. © 2011 Park et al.

Abstract:

Time-integrated and time-resolved microphotoluminescence studies were carried out on In xGa 1-xN quantum disks embedded in GaN nanocolumns grown by molecular beam epitaxy. Emission at ∼3.33 eV from confined states was detected and observed to blueshift with excitation power; a result of charge screening and the quantum confined Stark effect. The lifetime of the emission was measured to decrease with increasing excitation power, attributed to reduced band bending and resulting increased overlap of the confined electron and hole wave functions. © 2011 American Institute of Physics.

Abstract:

We investigated the carrier transition properties of the GaN/InGaN/GaN single quantum well bounded by AlGaN barriers. In order to confirm the carrier transition coming from the single quantum well, the single quantum well layer was etched by reactive ion etching method. The structural property of the samples was characterized by high resolution X-ray diffraction measurements. In micro-photoluminescence measurements, it is clearly shown that the donor bound exciton transition of the single quantum well sample was redshifted compared to the etched one due to strain. Moreover, a lot of peaks were observed below the GaN band gap energy due to carrier localization in the InGaN/GaN single quantum well, including carrier localization center and quantum confined states. The excitation power dependence and time resolved photoluminescence spectra were investigated to characterize the optical transition of the single quantum well© 2011 Elsevier B.V. All rights reserved.

Abstract:

Cavities embedded in photonic crystal waveguides offer a promising route towards large scale integration of coupled resonators for quantum electrodynamics applications. Here a strongly coupled system consisting of a single quantum dot and a cavity formed by the local width modulation of a photonic crystal waveguide is demonstrated. The resonance originating from the cavity is clearly identified from microphotoluminescence mapping of the scattered signal along the waveguide. The exciton-photon strong coupling regime is obtained by temperature control. © 2011 American Institute of Physics.