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Photoinduced light absorption in Ge/Si quantum dots
St. Petersburg Polytechnical University Journal: Physics and Mathematics. 2024. Vol. 17. No. 1.1. P. 105–112.
Ustimenko R. V., Karaulov D. A., Vinnichenko M. Y., I. S. Makhov, Firsov D. A., Sarkisyan H. A., Sargsian T. A., Hayrapetyan D. B.
Photoinduced absorption in nanostructures with doped Ge/Si quantum dots as well as in undoped structures, was studied. Spectra of photoinduced absorption at cryogenic temperatures under direct and indirect in real space resonant interband pumping, as well as time-resolved spectra were obtained. Two high-energy peaks detected in the absorption spectra may be associated with intraband hole transitions from the ground and excited states of quantum dots to the continuous spectrum. The low-energy peak corresponds to interlevel transitions of holes between the ground and excited states. The dynamics of the decay of high-energy peaks can be described in terms of fast and slow components associated with the capture of photoexcited carriers on the levels in a quantum dot. Structures with Ge/Si quantum dots can be used to develop mid-infrared detectors.
Publication based on the results of:
Das A., Hazarika A. P., Das S. K. et al., Physica B: Condensed Matter 2026 Vol. 738
Lemon grass (Cymbopogon citratus, LG-SiO2), horsetail (Equisetum debile, SG-SiO2), and cassava leaves (Manihot esculenta, CL-SiO2) were used to green-synthesize silica (SiO2) nanoparticles (NPs). While LG-SiO2 and SG-SiO2 had strong (101) peaks and a large 22° amorphous peak, XRD of CL-SiO2 verified crystallinity. LG-SiO2 (agglomerated porous), SG-SiO2 (rectangular-cube agglomerates), and CL-SiO2 (flake agglomerates) had different morphologies. The TEM image of LG-SiO2 revealed agglomerated ...
Added: June 4, 2026
Kornbleuth M., Opher M., Drake J. F. et al., Astrophysical Journal 2026 Vol. 1004 No. 1 P. 1–18
The shape of the heliosphere, regarded as comet-like since the 1960s, has recently been the subject of intense debate in the last decade. There is disagreement as to whether the heliospheric tail extends to ∼10,000 au in a comet-like shape or if it is short (∼400 au) with a split. Energetic neutral atom (ENA) maps from ...
Added: June 3, 2026
Карцев А. И., Nishant T., Saswata G. et al., Journal of Materials Chemistry C 2026 Article -
Overheating remains a critical limitation in high-performance electronic and computing systems,
necessitating the development of efficient thermal management fluids. In this work, a magnetically
responsive hybrid ferrofluid was developed by incorporating two-dimensional hexagonal boron nitride
(2D-hBN) nanosheets into a Mn–Zn–ferrite-based ferrofluid. The hybrid system retains magnetic
responsiveness while leveraging the high in-plane thermal conductivity and chemical stability of 2D-hBN
nanosheets. ...
Added: June 2, 2026
Fortuna A. S., A.I. Kartsev, Gorshenkov M. V. et al., Journal of Alloys and Compounds 2026 Vol. 1070 Article 188711
The τ-phase in Mn-Al-Ga alloys is a promising candidate for rare-earth-free permanent magnets. This study re-veals that the τ(γ₂)-phase in rapidly quenched Mn55Al36Ga9 ribbons contains a high density of dislocations, which
form antiphase boundaries (APBs). Using transmission electron microscopy and density functional theory, we
demonstrate that Mn atoms at these APBs couple antiferromagnetically. This antiferromagnetic interaction is
identified ...
Added: June 2, 2026
Dikhtievskaya K., Argunov E., Карцев А. И. et al., The Journal of Physical Chemistry Letters 2026 Vol. 17 No. 17 P. 4999–5004
In this study we revealed the effect of scandium doping on the electronic and superconducting properties of the MgB2 compound. Calculations demonstrate that Sc substitutes for Mg atoms, acting as an electron donor. Mg substitution diminishes the density of states in the σ-band and attenuates the electron–phonon coupling, thereby elucidating the reduction in critical temperature. Simultaneously, ...
Added: June 2, 2026
Duran E. ., Pulgar A., Izquierdo R. et al., Physica Status Solidi (A) Applications and Materials 2026 Vol. 223 No. 7 Article e202500942
Ceramic superconductors exhibit remarkable properties, including zero electrical resistance and potent magnetic behavior, operating at temperatures as high as the boiling points of liquid nitrogen (77 K) and liquid hydrogen (20 K). These characteristics position them as key enablers for sustainable technologies spanning electric propulsion, lossless energy transmission, advanced medical imaging, and quantum computation. This review presents ...
Added: June 1, 2026
Borisov V., Danilov V., Электросвязь 2025 № 12 С. 73–84
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Added: May 29, 2026
Arutyunov K., JIANG1 Q., FANG J. et al., Science China Information Sciences 2026 Vol. 69 No. 6 P. 1–11
Resonators based on nanoelectromechanical systems (NEMS) using two-dimensional (2D) materials with high-quality factors and excellent electrical control are critical for tunable coherent phonon dynamics, resonant sensors and wireless communications. However, their performance is fundamentally limited by the lack of a unified framework governing energy dissipation mechanisms and their electrical tunability. Here, we synergistically modulate both ...
Added: May 28, 2026
Elesin L., Shilov A., Jana S. et al., Advanced Functional Materials 2026 P. 1–10
Thermoelectric materials, long explored for energy harvesting and thermal sensing, convert heat directly into electrical signals. Extending their application to the terahertz (THz) frequency range opens opportunities for low-noise, bias-free THz detection, yet conventional thermoelectrics lack the sensitivity required for practical devices. Thermoelectric coefficients can be strongly enhanced near van Hove singularities (VHS), though these ...
Added: May 28, 2026
Degtyarev A., Bakhurin S., Yudin N., DSPA 2026 P. 1–6
This paper investigates one possible solution to the problem of self-interference cancellation (SIC) arising in the design of in-band full-duplex (IBFD) communication systems. Self-interference cancellation is performed in the digital domain using multilayer nonlinear models adapted via gradient-based optimization. The presence of local minima and saddle points during the adaptation of multilayer models limits the ...
Added: May 26, 2026
Qian X., Deng Y., Lev N. Shchur et al., Physica A: Statistical Mechanics and its Applications 2026 Vol. 696 Article 131679
We perform a Monte Carlo analysis of the Ising model on many three-dimensional lattices. By means of finite-size scaling we obtain the critical points and determine the scaling dimensions. As expected, the critical exponents agree with the three-dimensional Ising universality class for all models. The irrelevant field, as revealed by the correction-to-scaling amplitudes, appears to ...
Added: May 24, 2026
Melentiev P. N., Калмыков А. С., Гритченко А. С. et al., Успехи физических наук 2024 Т. 194 № 11 С. 1130–1145
Представлен краткий обзор достигнутого уровня оптических методов детектирования единичных молекул в биомедицинских приложениях. Показано, что регистрация флуоресценции единичных молекул красителей, ковалентно связанных с антителами (биомолекулами), совместно с использованием современных методов нанофотоники может быть применена для решения различных задач в биологии и медицине: визуализации биомолекул, токсинов, вирусных частиц, определения ультранизких концентраций аналитов напрямую во взятой пробе, ...
Added: May 21, 2026
Babichev A., Makhov I., Kryzhanovskaya N. et al., IEEE Journal on Selected Topics in Quantum Electronics 2026 Vol. 32 No. 6 Article 1700208
Micropillar cavity lasers demonstrate operation up to 255 K. At this temperature, the lasing threshold and Q-factor, extracted at lasing threshold for a 4 μm diameter pillar are about 2 mW and 16800. For pillar lasers, the concept of which is based on an optical aperture, continuous-wave lasing is realized at room temperature (300 K). ...
Added: March 23, 2026
Бабичев А. В., Makhov I., Kryzhanovskaya N. et al., Письма в Журнал технической физики 2025 № 21 С. 58–62
Продемонстрирована генерация в микролазерах на основе вертикального микрорезонатора при температуре 244 K. Пороговая поглощенная оптическая мощность, длина волны генерации и добротность микролазера с диаметром 4 µm составили ∼ 2.8 mW, 989 nm и 12 000 соответственно. Минимальная пороговая поглощенная оптическая мощность (250 µW) соответствует температуре 168 K. ...
Added: March 13, 2026
Babichev A., Blokhin A., Zadiranov Y. et al., Applied Physics Letters 2026 Vol. 128 No. 5 Article 051105
High-quality micropillar cavities were grown using molecular-beam epitaxy. Stable continuous-wave lasing at room temperature was demonstrated for microlasers with semiconductor and hybrid output mirrors. At 300 K, single-mode lasing was demonstrated for micropillars with a diameter of 5 um at a wavelength of 960 nm, with a minimum lasing threshold of 1.2 mW and the ...
Added: March 13, 2026
S.D. Komarov, Vainilovich A. G., G.A. Feigin et al., St. Petersburg Polytechnical University Journal: Physics and Mathematics 2025 Vol. 18 No. 3.1 P. 209–213
Fabrication, optical study, and mode modeling of III-N microdisk resonators with InGaN/GaN quantum wells on Al2O3 are presented. It is shown that the created epitaxial structures have high optical quality, and the microresonators support high-Q whispering gallery modes. ...
Added: December 11, 2025
Zhukov A., Moiseev E., Makhov I. et al., Письма в Журнал технической физики 2025 Т. 51 № 20 С. 32–35
The dynamic characteristics of an InGaAs/GaAs quantum dot microring laser were investigated using small-signal high-frequency current modulation at 55 °C. The maximum modulation bandwidth was 3.7 GHz, and the energy consumption during optical transmission was estimated to be 4.2–6.4 pJ/bit. The temperature dependencies of the parameters affecting the speed of operation (K-factor, threshold current, current ...
Added: October 29, 2025
Пеетерс Ф. М., Mahdavifar M., Khoeini F., Journal of Applied Physics 2024 Vol. 136 Article 184301
The impact of vacancies on spin-resolved electronic properties of quantum dots (QDs) in phosphorene-based junctions is investigated numerically. Regardless of the crystal orientation, a phosphorene nanoribbon containing a monovacancy is found to exhibit a topological quasi-flatband that emerges within the bandgap. The electronic properties of QDs, including spatial confinement and energy level distribution, can be ...
Added: September 15, 2025
Konstantin A. Ivanov, Alexey E. Zhukov, Eduard I. Moiseev et al., Journal of Applied Physics 2025 Vol. 138 No. 10 Article 103104
Microlasers supporting whispering gallery modes attract great interest because of their potential use in photonic integrated circuits: they have size just an order of magnitude larger than their emission wavelength and exhibit good thermal and dynamic properties. It is usually assumed that in disk microlasers a whispering gallery mode of the highest azimuthal order and ...
Added: September 11, 2025
Fominykh N., Fedosov I. S., Kryzhanovskaya N. et al., Письма в Журнал технической физики 2025 Т. 51 № 19 С. 11–14
The directed emission output of microdisk lasers through a coupled optical waveguide fabricated from the same heterostructure has been investigated. Disks with diameters of 30 and 40 µm containing an active region based on InGaAs/GaAs quantum dots were studied. To reduce absorption losses in the waveguide, a forward bias was applied to it. At a ...
Added: August 27, 2025
Бабичев А. В., Makhov I., Kryzhanovskaya N. et al., Письма в Журнал технической физики 2025 Т. 51 № 5 С. 41–44
Представлены результаты исследования расщепления мод шепчущей галереи в лазерах спектрального диапазона 930-950 nm на основе вертикального микрорезонатора. Использование распределенных брэгговских отражателей на основе чередующихся слоев Al0.2Ga0.8As/Al0.9Ga0.1As, не поглощающих на длине волны накачного лазера, позволило снизить величину пороговой мощности оптической накачки до 180 μW (для 3 μm-микролазера). Добротность микрорезонатора на пороге генерации для мод шепчущей галереи ...
Added: April 30, 2025
Solodovnik M., Balakirev S., Ivan S. Makhov et al., Applied Surface Science 2025 Vol. 700 Article 163211
Despite the rapid growth in the number of studies devoted to quantum dot (QD) formation on patterned substrates,
segregation effects that have a significant impact on the properties of QD-based heterostructures remain
largely unexplored. In this paper, we focus on the influence of segregation under different capping regimes on the
optical properties of various InAs/GaAs nanostructures: QDs and ...
Added: April 17, 2025
Anandkumar M., Kesavan K. P., Sudarsan S. et al., Gels 2025 Vol. 11 No. 2 Article 117
Tailoring the bandgap of a material is necessary for improving its optical properties. Here, the optical bandgap of high-entropy oxide Ce0.2Gd0.2Sm0.2Y0.2Zr0.2O2-δ (HEO) nanoparticles was modified using Pr3+. Various concentrations of Pr3+ (x = 0, 0.01, 0.02, 0.05, 0.075, 0.1, 0.15) were incorporated into the host high-entropy oxide using a gel combustion synthesis. After the gel ...
Added: February 18, 2025
Solodovnik M. S., Kirichenko D., Dukhan D. et al., Applied Surface Science 2025 Vol. 688 Article 162373
This paper proposes a new approach to nanoscale patterning of GaAs substrates that allows formation of subcritical (below the Stranski-Krastanov critical thickness) low-density quantum dots. We demonstrate that the removal of the GaAs native oxide under molecular arsenic flux stimulates the formation of nanosized holes on the substrate surface. Geometric characteristics of these holes (diameter, ...
Added: January 21, 2025