Novel Highly Parallel and Systolic Architectures using Quantum Dot-Based Hardware
In this paper, we present novel parallel architectures based on Quantum-dot Cellular Automata (QCA) hardware.
Quantum-Dot Hardware Systolic Arrays Permutation M↗
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Tunable Intersublevel Transitions in Self-forming Semiconductor Quantum Dots
Interfacial compositional disordering in InGaAs/GaAs quantom dots has been used to tune their intersublevel energy spaceings (delta E subscript [(i + 1) - i]).
Semiconductor Tunable Intersublevel Transitions↗
Room-temperature continuous operation of InAsSb quantum-dot lasers near 2 mu m based on (100) InP substrate
Single-stack InAsSb self-assembled quantum-dot lasers based on (001) InP substrate have been grown by metalorganic vapor-phase epitaxy. The narrow ridge waveguide lasers lased at wavelengths near 2 mu m up to 25 degrees C in continuous-wave operation. At room temperature, a differential quantum efficiency of 13 percent is obtained and the maximum output optical power reaches 3 mW per facet with a threshold current density of 730 A/cm(sup 2). With increasing temperature the emission wavelength is extremely temperature stable, and a very low wavelength temperature sensitivity of 0.05 nm/degrees C is measured, which is even lower than that caused by the refractive index change.
Semiconductor lasers quantum dots↗
Dislocation-induced Charges in Quantum Dots: Step Alignment and Radiative Emission
A transition between two types of step alignment was observed in a multilayered InGaAs/GaAs quantum-dot (QD) structure. A change to larger QD sizes in smaller concentrations occurred after formation of a dislocation array.
radiative emission step alignment InGaAs/GaAs quan↗
Ensemble Interactions in Strained Semiconductor Quantum Dot
Large variations in InGaAs quantum dot concentrations were obtained with simultaneous growths on vicinal GaAs[001] substrates with different surface step densities.
quantum dots optical properties photoluminescence↗
Inhibited Carrier Transfer in Ensembles of Isolated Quantum Dots
We report significant differences in the temperature dependent and time-resolved photoluminescence(PL) from low and high surface density InGaAs/GaAs quantum dots (QDs).
quantum dots time resolved photoluminescence carri↗
Lasing characteristics of InAs quantum dot laers on InP substrate
Single-stack InAs self-assembled quantum dots (QD) lasers based on InP substrate have been grown by metalorganic vapor phase epitaxy. The narrow ridge waveguide lasers lased up to 260 K in continuous wave operation, and near room temperature in pulsed mode, with wavelengths between 1.59 to 1.74 mu m.
quantum dot semiconductor laser↗
Magneto-optical response of InAs lens-shaped self-assembled quantum dots
In this work, we demonstrate a realistic modeling of the electronic structure for InAs self-assembled quantum dots and investigate the magneto-optical response, i.e., Zeeman splitting and transition rates between electron and hole levels.
quantum dot Lande g factor magnetic field↗
Atomistic simulations in nanostructures composed of tens of millions of atoms: importance of long-range strain effects in quantum dots
Strain in self-assembled quantum dots is a long range phenomenon, and its realistic determination requires a large computational domain.
nanostructures↗
The effect of the strain relaxation in InAs/GaAs stacked quantum dots and multiple quantum wells on the Raman spectrum
Atomistic-level simulations of the Raman shift in InAs/GaAs multiple quantum well (MQW) and stacked quantum dot (SQD) structures as a function of interlayer separation are reporter.
phonons↗
Atomistic-level simulation of the vibration spectrum of quantum dot crystals
Quantum dot crystal structures (QDCs) have been recently proposed as the building blocks of novel thermoelectric devices.
phonons↗
Continuous-wave operation of InAsSb/InP quantum - dot lasers near 2 (mu)m at room temperature
InAsSb quantum-dot lasers near 2 pm were demonstrated in cw operation at room temperature with a threshold current density of below 1 kA/cm, output power of 3 mW/facet and a differential quantum efficiency of 13%.
quantum dot↗
2 Micrometers InAsSb Quantum-dot Lasers
InAsSb quantum-dot lasers near 2 micrometers were demonstrated in cw operation at room temperature with a threshold current density of 733 A,/cm(sup 2), output power of 3 mW/facet and a differential quantum efficiency of 13%.
quantum dot↗
Quantum dots based rad-hard computing and sensors
Quantum Dots (QDs) are solid state structures made of semiconductors or metals that confine a small number of electrons into a small space. The confinement of electrons is achieved by the placement of some insulating material(s) around a central, well conducting region. Thus, they can ve viewed as artificial atoms.
quantum↗
Room temperature continuous-wave operation of InAsSb quantum-dot lasers near 2 mu m based on (001) InP substrate
Single-stack InAsSb self-assembled quantum-dot lasers based on (001) InP substrate have been grown by metalorganic vapor-phase epitaxy.
quantum↗
Probing the Origin of the Open Circuit Voltage in Perovskite Quantum Dot Photovoltaics
Perovskite quantum dots (PQDs) have many properties that make them attractive for optoelectronic applications, including expanded compositional tunability and crystallographic stabilization. While they have not achieved the same photovoltaic (PV) efficiencies of top-performing perovskite thin films, they do reproducibly show high open circuit voltage (VOC) in comparison. Further understanding of the VOC attainable in PQDs as a function of surface passivation, contact layers, and PQD composition will further progress the field and may lend useful lessons for non-QD perovskite solar cells. Here, we use photoluminescence-based spectroscopic techniques to understand and identify the governing physics of the VOC in CsPbI3 PQDs. In particular, we probe the effect of the ligand exchange and contact interfaces on the VOC and free charge carrier concentration. The free charge carrier concentration is orders of magnitude higher than in typical perovskite thin films and could be tunable through ligand chemistry. Tuning the PQD A-site cation composition via replacement of Cs+ with FA+ maintains the background carrier concentration but reduces the trap density by up to a factor of 40, reducing the VOC deficit. These results dictate how to improve PQD optoelectronic properties and PV device performance and explain the reduced interfacial recombination observed by coupling PQDs with thin-film perovskites for a hybrid absorber layer.
perovskite quantum dot↗
A review of radiation-induced damage to quantum dots
Quantum dots (QDs) are versatile nano structures that have applications in many fields of research and production, including biosensor technology, computing, photovoltaics, and optoelectronics. QDs have gained interest in the field of radiation detection because of their relative ease of production, tunable photoluminescence, and sensitivity to ionizing radiation. The photoluminescent properties of QDs diminish proportionally to prolonged ionizing radiation interactions, leading many groups to seek out these materials as potential candidates for the next generation of inexpensive, easily manufactured dosimetry and sensors. To use QDs in these applications, the mechanisms of radiation damage to the nanomaterial must be clearly understood and characterized. Herein, we review the study of ionizing radiation damage to QDs. First, the synthesis and properties of QDs are briefly discussed. Next, the radiation damage to QDs due to heavy charged particles, fast electrons, high energy photons, and neutrons are detailed. After this, experimental methods and modelling of QDs in radiation environments are examined. Lastly, future research directions are provided. The goal of this review is to aid in understanding the ionizing radiation effects on QD-based devices.
Snow, Jesse [University of Utah, Salt Lake City, U↗
Unraveling the Growth Mechanism of Strongly Confined CsPbBr 3 Perovskite Quantum Dots under Thermodynamic Equilibrium Control
Size-confined lead halide perovskite quantum dots (PQDs) are promising materials for optoelectronic devices. Large quantities of PQDs with high ensemble uniformity are often needed for device fabrication. The thermodynamic-equilibrium-controlled synthesis can produce PQDs with good size and shape uniformity. Unfortunately, scaling up this synthesis often produces unwanted perovskite nanoplatelets (NPLs). To date, the PQD and NPL growth mechanism under thermodynamic equilibrium control remains unexplored. We discovered that the growth of size-confined CsPbBr 3 PQDs is mediated by ultrasmall (~ 2.4 nm) metastable nanoclusters. These nanoclusters can eventually grow into PQDs when sufficient Cs-precursors are provided. Otherwise, the unreacted nanoclusters will self-assemble and fuse into NPLs during the synthesis and/or PQD purification. Furthermore, by controlling the homogeneous growth of nanoclusters, strongly confined (≤ 5 nm) PQDs with high size uniformity can be produced at the gram scale.
77 NANOSCIENCE AND NANOTECHNOLOGY↗