[en] Results are presented on microlasers with quantum dot active region grown on either GaAs or Si substrates. The optical resonator of these lasers represents a microdisk supporting whispering-gallery modes with a Q-factor in excess of 30’000. When operating in continuous-wave mode without temperature stabilization, the microlasers have the threshold currents of mA-range with the minimal threshold current density of 250 A/cm². Under direct small-signal modulation, the -3dB modulation bandwidths were measured to be above 6 GHz with a little effect of self-heating on the performance. The consumed electric power was estimated to be about 2 pJ/bit. The achieved performance is a significant breakthrough in realization of low-threshold high-speed temperatrure-stable operation of microlasers compared with the previously reported parameters for the devices of comparable sizes. (paper)

[en] This article demonstrates the phased creation of heterostructures containing GaPN and GaPAsN layers on Si substrates grown by molecular-beam epitaxy. A technique of preparing a silicon surface for epitaxial growth, the creation of a GaP initial layer, and optical studies of GaPN and GaPAsN layers are described. It is shown that high-quality GaP(As)N epitaxial layers can be created on Si substrates by molecular-beam epitaxy. (paper)

[en] Lasing in microdisks with an asymmetric waveguide formed by selective oxidation was achieved under optical pumping in the temperature range 5-180 K. InGaAs quantum dots (QDs) formed by submonolayer deposition were used as the active region. The experimentally determined quality factor Q of a microdisk cavity is no less than 10⁴. The temperature shift of the resonance mode wavelength is attributed to the dispersion and the temperature dependence of the effective refractive index of a microdisk. The observed temperature dependence of the lasing threshold is related to thermal excitation of carriers from QDs into GaAs

[en] We performed a numerical study of optical whispering gallery modes in microdisk resonators modified via their embedding in a homogeneous dielectric surrounding or covering with a thin dielectric layer. Mode spectra and electromagnetic field distributions were calculated through the solution of the Helmholtz equation using COMSOL Multiphysics environment. It is shown that the modification results in the decimation of the resonator modes. (paper)

[en] We discuss the molecular beam epitaxy (MBE) growth methods of emission wavelength control and property investigations for different types of InAs/(In)GaAsN/GaAs heterostructures containing InGaAsN quantum-size layers: (1) InGaAsN quantum wells deposited by the conventional mode in a GaAs matrix, (2) InAs quantum dots deposited in a GaAsN matrix or covered by an InGaAs(N) layer, and (3) InAs/InGaAsN/GaAsN strain-compensated superlattices with quantum wells and quantum dots. The structures under investigation have demonstrated photoluminescence emission in a wavelength range of ∼1.3-1.8 μm at room temperature without essential deterioration of the radiative properties.

[en] InGaN/GaN nanorod structure is presented for the fabrication of light-emitting diodes by means of plasma-chemical etching. Processes of the etching of nanorods and the defect passivation in a planar InGaN/GaN quantum dot heterostructure are studied. The obtained results allow creating the light-emitting diode nanostructure with a greater efficiency compared to the classical planar technology.

[en] We probe the resonance properties of complex plasmonic structures by Scanning Near-field Optical Microscopy (SNOM). Groups of three differently arranged silver nanoparticles covered with Surface-Enhanced Raman Scattering (SERS) analyte Rhodamine 6G were chosen to visualize electric field distribution nearby the nanostructures. The particles were grown on the surface of a silver-ion-exchanged glass using thermal poling and annealing of the processed glass substrate in hydrogen atmosphere. The morphology of the nanoparticles and their arrangement in the groups were characterized with Atomic Force Microscopy (AFM). The near-field SERS maps superimposed on the AFM scans of the studied groups of nanoparticles visualize the Raman hotspots with 100 nm resolution. (paper)

[en] The optical-reflection spectra of microarrays of silicon nanopillars are studied in the visible and near-IR regions. The microarrays of silicon nanopillars are formed by electron-beam lithography and reactive ion etching. The reflection spectra of nanopillar arrays with pitches of 400, 600, 800, and 1000 nm are measured. The height of nanopillars in the array is 0.5 μm, and the diameter varies from 150 to 240 nm. It is noted that the spectral features of the reflection are caused by increased absorption of individual nanopillars and interference effects inside the array. A relation between the geometric parameters of nanopillars and the resonance reflection characteristics is determined taking into account the influence of the substrate.

[en] We report results of characterization of injection microdisk lasers based on active layers employing 2, 5 and 10 layers of InGaAs quantum well-dot structures. The microlasers operate in continuous wave regime at room temperature without external cooling. The minimal microdisk diameter 10 µm is obtained for 5 layers of InGaAs quantum well-dot structures. Lasing wavelength is around 1.1…1.15 µm, minimal threshold current is 1.6 mA (threshold current density 900 A/cm²). (paper)

[en] Multijunction solar cells grown on group IV substrates using III-V compounds are very promising due to their high efficiency (over 40%). Further development of these structures is mainly focused on III-V layers while bottom sub-cell based on p-n junction in the substrate is disregarded. However, high temperatures required for III-V epitaxy as well as diffusion over III-V/IV interface may affect minority carrier lifetime in the substrate. GaAs/GaInP/(AlAs)/Ge heterostructures were grown by MOCVD. Thermal annealing at the conditions of triple-junction solar cells was performed and photoluminescence spectra for these structures were investigated. (paper)