A5052870309- Semiconductor Quantum Structures and Devices
- Quantum Dots Synthesis And Properties
- Quantum Information and Cryptography
- Semiconductor Lasers and Optical Devices
- Photonic and Optical Devices
- Quantum and electron transport phenomena
- nanoparticles nucleation surface interactions
- GaN-based semiconductor devices and materials
- Surface and Thin Film Phenomena
- Semiconductor materials and devices
- Nanowire Synthesis and Applications
- Molecular Junctions and Nanostructures
- Advancements in Semiconductor Devices and Circuit Design
- Mechanical and Optical Resonators
- Cold Atom Physics and Bose-Einstein Condensates
- Atomic and Subatomic Physics Research
- Quantum-Dot Cellular Automata
- Chemical and Physical Properties of Materials
- Electronic and Structural Properties of Oxides
- Photonic Crystals and Applications
- Quantum, superfluid, helium dynamics
- Quantum optics and atomic interactions
University College Cork
2015-2021
National University of Ireland
2017
A study of highly symmetric site-controlled pyramidal In0.25Ga0.75As quantum dots (QDs) is presented. It discussed that polarization-entangled photons can be also obtained from QDs different designs the one already reported in Juska et al. [Nat. Photonics 7, 527 (2013)]. Moreover, some limitations for a higher density entangled photon emitters are addressed. Among these issues (1) remaining small fine-structure splitting and (2) an effective QD charging under non-resonant excitation...
Strain-free epitaxial quantum dots (QDs) are fabricated by a combination of Al local droplet etching (LDE) nanoholes in AlGaAs surfaces and subsequent hole filling with GaAs. The whole process is performed conventional molecular beam epitaxy (MBE) chamber. Autocorrelation measurements establish single-photon emission from LDE QDs very small correlation function g ((2))(0)≃ 0.01 the exciton emission. Here, we focus on influence initial depth QD optical properties goal to create deep holes...
We report a model for metalorganic vapor-phase epitaxy on non-planar substrates, specifically V-grooves and pyramidal recesses, which we apply to the growth of InGaAs nanostructures. This model, based set coupled reaction-diffusion equations, one each facet in system, accounts facet-dependence all kinetic processes (e.g., precursor decomposition, adatom diffusion, lifetimes) has been previously applied account temperature, concentration, temporal-dependence AlGaAs nanostructures GaAs (111)B...
The influence of hydride exposure on previously unreported self-assembled InP(As) nanostructures is investigated, showing an unexpected morphological variability with growth parameters, and producing a large family by metalorganic vapour phase epitaxy, from dome ring-like structures to double dot in ring ensembles. Moreover, preliminary microphotoluminescence data are indicating the capped rings system as interesting candidate for single quantum emitters at telecom wavelengths, potentially...
Formation, emission, and lasing properties of strain-free InP(As)/AlInAs quantum dots (QDs) embedded in AlInAs microdisk (MD) cavity were investigated using transmission electron microscopy photoluminescence (PL) techniques. In MD structures, the QDs have nano-pan-cake shape with height ∼2 nm, lateral size 20–50 density ∼5 × 109 cm−2. Their emission observed at ∼940 nm revealed strong temperature quenching, which points to exciton decomposition. It also showed unexpected type-I character,...
We report on stacked multiple quantum dots (QDs) formed inside inverted pyramidal recesses, which allow for the precise positioning of QDs themselves. Specifically, we fabricated double with varying inter-dot distances and ensembles more than two nominally highly symmetric QDs. For each, effect interaction between is studied by characterizing a large number through photoluminescence spectroscopy. A clear red-shift emission energy observed together change in orientation its polarization,...
Pyramidal quantum dots have been established as a promising source of single and entangled photons for information applications. However, their small brightness calls new strategies both to boost extraction efficiency plan heterogeneous integration protocols in view demanding processing In this paper we show that simple technique based on chemo-mechanical planarization (CMP) can effectively remove several obstacles the further kind system, pave way use in-situ lithographic techniques tag...
A three-dimensional ordered and self-organized semiconductor system emitting highly-polarized light in the yellow-orange visible range (580-650 nm) is presented, comprising self-assembled in-plane AlInP wires vertically stacked regularly-spaced columns. More than 200 per column without detectable defect formation could be stacked. Theoretical simulations temperature-dependent photoluminescence provided a benchmark to engineer multilayered structures showing internal quantum efficiency at...
The first site-controlled quantum dot light-emitting diode of non-classical light – single and polarization-entangled photons violating Bell's inequality is presented in this work. structure based on highly symmetric, single, pyramidal dots.
AlInAs microdisk cavities having quality factor Q ∼ 15 000 were fabricated from lattice-matched InP/AlInAs (interface/aggregation) quantum dot (QD) structures using wet chemical etching. The QD emission coupled to whispering gallery modes was observed at spectral range 920 - 1000 nm temperatures of 10 160 K. laser generation with threshold power density 50 W/cm2 T = K under optical pumping. It found that the spontaneous coupling β equals 0.23 for these microdisks. low temperature lasing...
We investigated and demonstrated a 1.3 μm band laser grown by metalorganic vapor-phase epitaxy (MOVPE) on specially engineered metamorphic parabolic-graded InxGa1–xAs buffer epitaxial structure GaAs substrate. Bottom upper cladding layers were built as combination of AlInGaAs InGaP alloys in superlattice sequence. This was implemented to overcome (previously unreported) detrimental surface dynamics instabilities: when single are utilized achieve thick structures, instabilities induce defect...
We report on the performance of electrically-injected pyramidal quantum dots (PQDs) in terms single-photon emission. previously presented generation entangled photon pairs from similarly structured devices. Here we show that it is also possible to obtain single-photons upon continuous wave excitation as well pulsed excitation, obtaining a low g2(0) 0.088 ± 0.059, by discarding re-excitation events within single pulse applying time-gating techniques.
The effects of growth conditions choice and post-growth layer exposure to hydrides have been studied in InP/AlInAs self-organized nanostructures grown by low pressure MOVPE. Here we show how the size density low-dimensional structures can be manipulated controlled changing parameters. final shape is governed influence exposure. For example, arsenization protocols original InP dot represent crucial step transformation from dots rings (and domes). We also demonstrate photoluminescence...
In this work we present the modeling of Metal Organic Vapour-Phase Epitaxy (MOVPE) InGaAs nanostructures in non-planar V-grooves and pyramidal recesses. Our well-established growth model has been first employed to find a set optimized kinetic parameters for epitaxy by fitting morphological compositional evolution during <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.12</inf> Ga xmlns:xlink="http://www.w3.org/1999/xlink">0.88</inf> As V-groove...
In this report, we demonstrate for the first time, a platform to generate polarization-entangled photons, based on highly symmetric pyramidal quantum dots, achieving both site-controlled and electrically-injected capabilities at same time. Combining with time gating techniques, our triggered light sources were proven violate Bell's inequalities, an even more stringent examination applications future information technologies.
Light emitting III-V materials have shown a severe reduction in efficiency for wavelengths the range 550-590 nm both InGaN and AlInGaP compounds. Quantum dot (QD) based active layer could afford promise to solve some of these limitations, providing an interesting route towards high performance optoelectronic devices yellow band. Here we investigate photoluminescence properties multilayered AlInP/AlInGaP QD system at ~580 (at 10 K). The small AlInP size (1-2 MLs) investigation different...