Study of waveguide absorption in InGaAs ”quantum well-dots” heterostructures
Electronic states in a novel type of quantum-size heterostructures referred to as InGaAs quantum welldots
(QWDs) were experimentally studied using absorption in stripe waveguides of different lengths
based on a single, double, five, and ten QWD layers. The value of the modal absorption was measured
to be 70 cm−1 and 90 cm−1 for ground-state transition and high-energy one, respectively. The structure
of electronic states in the QWDs is also analyzed by polarization-resolved waveguide absorption and
the dependence of a polarization degree on the chip length is discussed. TM polarization of the heavyhole-
based optical transition photoresponse observed in the long waveguides is attributed to the light
depolarization due to the scattering on the QWD heterointerfaces.
In this work authors presented new approach to investigation of multilayer heterostructures by joint calculation HRXRD and XRR data.
Three-particle complexes consisting of two holes in the completely filled zero-electron Landau level and an excited electron in the unoccupied first Landau level are investigated in a quantum Hall insulator. The distinctive features of these three-particle complexes are an electron-hole mass symmetry and the small energy gap of the quantum Hall insulator itself. Theoretical calculations of the trion energy spectrum in a quantizing magnetic field predict that, besides the ground state, trions feature a hierarchy of excited bound states. In agreement with the theoretical simulations, we observe new photoluminescence lines related to the excited trion states. A relatively small energy gap allows the binding of three-particle complexes with magnetoplasma oscillations and the formation of plasmarons. The plasmaron properties are investigated experimentally.
The results of measurements of an electron density in a microwave plasma filament in dense gas (argon) are reported. The electron density has been determined on the basis of Stark broadening of lines detected in the absorption spectrum. A high-resolution spectrometer incorporating GaAlAs diode laser operating at 870 nm has been used to measure Stark broadening and shifts of the argon line. The electron density in the filament was found to increase from the initial level of 10 exp 12/cu cm to value n sub e greater than 10 exp 16/cu cm. The dependencies of the electron density on gas pressure and microwave power density are presented.
Solar cells based on organometal halide perovskites have recently become very promising among other materials because of their cost-effective character and improvements in efficiency. Such performance is primarily associated with effective light absorption and large diffusion length of charge carriers. Our paper is devoted to the explanation of large diffusion lengths in these systems. The transport mean free path of charged carriers in a perovskite/TiO2heterojunction that is an important constituent of the solar cells have been analyzed. Large transport length is explained by the planar diffusion of indirect excitons.Diffusion length of the coupled system increases by several orders compared to single carrier length due to the correlated character of the effective field acting on the exciton.
Magneto-fermionic condensate under study is a Bose-Einstein condensate of cyclotron spin-flip magnetoexcitons in a quantum Hall insulator. This condensate features unique properties such as millisecond range lifetime and hundreds of micrometers of propagation length. In this study, utilizing the photo-induced resonant reflection technique, we measured the exciton escape time. Finally, we estimated the exciton condensate propagation velocity as 25 m/s, which is much higher than a single particle propagation velocity. We also proposed a mechanism of exciton condensation.
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.
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.