Light Emitting Devices Based on Quantum Well-Dots
We review epitaxial formation, basic properties, and device applications of a novel type of nanostructures of mixed (0D/2D) dimensionality that we refer to as quantum well-dots (QWDs). QWDs are formed by metalorganic vapor phase epitaxial deposition of 4–16 monolayers of InxGa1−xAs of moderate indium composition (0.3 < x < 0.5) on GaAs substrates and represent dense arrays of carrier localizing indium-rich regions inside In-depleted residual quantum wells. QWDs are intermediate in properties between 2D quantum wells and 0D quantum dots and show some advantages of both of those. In particular, they offer high optical gain/absorption coefficients as well as reduced carrier diffusion in the plane of the active region. Edge-emitting QWD lasers demonstrate low internal loss of 0.7 cm−1 and high internal quantum efficiency of 87%. as well as a reasonably high level of continuous wave (CW) power at room temperature. Due to the high optical gain and suppressed non-radiative recombination at processed sidewalls, QWDs are especially advantageous for microlasers. Thirty-one μm in diameter microdisk lasers show a high record for this type of devices output power of 18 mW. The CW lasing is observed up to 110 °C. A maximum 3-dB modulation bandwidth of 6.7 GHz is measured in the 23 μm in diameter microdisks operating uncooled without a heatsink. The open eye diagram is observed up to 12.5 Gbit/s, and error-free 10 Gbit/s data transmission at 30 °C without using an external optical amplifier, and temperature stabilization is demonstrated.
The conference is devoted to fundamental problems of semiconductor physics.Main sections of the program: 1. Bulk semiconductors: electrical and optical properties, relaxation of charge carriers, ultrafast phenomena, excitons, phonons, phase transitions, ordering. 2. Surface, films, layers: epitaxy, atomic and electronic structure of the surface, adsorption and surface reactions, processes of formation (self-organization) of nanoclusters, STM and AFM, optical microscopy of the near field. 3. Heterostructures, superlattices, one-dimensional systems: structural and optical properties, electronic transport. 4. Two-dimensional systems: structural, electronic, magnetic and optical properties, tunneling, localization, phonons, plasmons, quantum Hall effect, correlation effects. 5. Zero-dimensional systems (quantum dots, nanocrystals): energy spectrum, optical properties, tunnel transport. 6. Spin phenomena, spintronics, nanomagnetism. 7. Impurities and defects (bulk semiconductors and quantum-dimensional structures): impurities with shallow and deep levels, magnetic impurities, structural defects, disordered semiconductors. 8. High-frequency phenomena in semiconductors (microwave and terahertz range). 9. Carbon and graphene-like nanomaterials, transition metal dichalcogenide monolayers, perovskites, organic semiconductors, molecular systems. 10. Photonic crystals, microresonators and metamaterials. Nanophotonics. 11. Semiconductor devices: technology, research methods, and nanodevices. 12. Nano-and optomechanics. 13. Topological insulators and Weyl semimetals.Выделите текст, чтобы посмотреть примерыДелитесь своими подборкамиСоздавайте подборки переводов для учёбы, работы или просто так и используйте вместе с друзьямиПопробоватьПримерыУстановите приложение на смартфон и работайте офлайн+Установить ПереводчикСообщение отправленоОтправить ещё разПереводите в Яндекс.Браузере
In this paper, we would like to suggest the algorithm of optoelectronic devices’ thermal working modes providing method. It solves the problem of gaining the projected working accuracy in high heat load including internal heat release on electronic components of printed circuit assemblies and optical part of optoelectronic device – the problem that is often faced by optoelectronic devices’ designers. We focus on implementation of this method in Zeeman-based frequency biasing laser gyroscope also known as Zeeman laser gyroscope. Below was given the example of the electronic assembly/component thermal model testing and Zeeman laser gyroscope thermal model was built. Note that the using method is applicable not only for Zeeman laser gyroscope but also for vast variety of optoelectronic devices. Implementation of this method in optoelectronic devices’ design allows us to get system approach and improve reliability and working accuracy to required levels.
The photoemission of free charge carriers into high-ohmic semiconductor created by light illumination of near-contact-area of ohmic contacts to cadmium telluride sample was investigated. It was revealed, that near-contact-area light illumination influences both on contact transition resistance and on volume conductivity of the crystal due to increasing of main charge carrier concentration. The method of separate determination of contact transition and sample volume resistances, suitable for high-ohmic semiconductors, was suggested.
Manifestations of quantum interference effects in macroscopic objects are rare. Weak localization is one of the few examples of such effects showing up in the electron transport through solid state. Here, we show that weak localization becomes prominent also in optical spectroscopy via detection of the electron spin dynamics. In particular, we find that weak localization controls the free electron spin relaxation in semiconductors at low temperatures and weak magnetic fields by slowing it down by almost a factor of two in n-doped GaAs in the metallic phase. The weak localization effect on the spin relaxation is suppressed by moderate magnetic fields of approximately 1 T, which destroy the interference of electron trajectories, and by increasing the temperature. The weak localization suppression causes an anomalous decrease of the longitudinal electron spin relaxation time T1 with magnetic field, in stark contrast with the well-known magnetic-field-induced increase in T1. This is consistent with transport measurements, which show the same variation of resistivity with magnetic field. Our discovery opens up a vast playground to explore quantum magnetotransport effects optically in the spin dynamics.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
Let G be a semisimple algebraic group whose decomposition into the product of simple components does not contain simple groups of type A, and P⊆G be a parabolic subgroup. Extending the results of Popov , we enumerate all triples (G, P, n) such that (a) there exists an open G-orbit on the multiple flag variety G/P × G/P × . . . × G/P (n factors), (b) the number of G-orbits on the multiple flag variety is finite.
I give the explicit formula for the (set-theoretical) system of Resultants of m+1 homogeneous polynomials in n+1 variables