ROUGHNESS AND STRUCTURE OF InGaAsN THIN FILMS ON Si

Методом импульсного лазерного напыления в атмосфере аргоно-азотной газовой смеси из мишени InGaAs впервые были получены тонкие пленки InGaAsN на подложках GaAs и Si. Мишень lnGaAs формировалась методом одноосного прессования из порошков GaAs и lnAs. Методами атомно силовой микроскопии и рентгеновской дифракции исследованы морфология поверхности и структура данных тонких пленок. Показано, что пленки InGaAsN на Si имеют средний размер кристалла 0,93 нм, а пленки и InGaAsN на GaAs - 0,99 нм. Определено, что уменьшение давления аргоно-азотной смеси при импульсном лазерном напылении тонких пленок InGaAsN на подложках GaAs и Si приводит к снижению значения среднеквадратичной шероховатости поверхности. Наименьшую среднеквадратическую шероховатость равную 0,25 нм имела тонкая пленка InGaAsN на подложке GaAs, полученная в вакууме, наибольшую среднеквадратическую шероховатость имела тонкая пленка InGaAsN на подложке Si, полученная при давления аргоно-азотной смеси от 10 Па - 19,37 нм. By the method of pulsed laser deposition in atmosphere of an argon-nitrogen gas mixture, for the first time thin InGaAsN films on GaAs and Si substrates were obtained from the InGaAs target. The InGaAs target was formed by uniaxial pressing from GaAs and InAs powders. The surface morphology and structure of these thin films are studied by atomic force microscopy and X-ray diffraction. It is shown that InGaAsN films on Si have an average crystal size of 0,93 nm, and InGaAsN films on GaAs of 0,99 nm. It is determined that a decrease in the pressure of an argon-nitrogen mixture during pulsed laser deposition of thin InGaAsN films on GaAs and Si substrates leads to a decrease in the value of the root- mean-square roughness of the surface. The smallest root-mean-square roughness equal to 0,25 nm had a thin InGaAsN film on a GaAs substrate obtained in vacuum, the largest root-mean- square roughness of 19,37 nm had a thin InGaAsN film on a Si substrate obtained at the argon-nitrogen mixture pressure of 10 Pa -.

Improving the Physical and Mechanical Performance of Laminated Wooden Structures by Low-Temperature Plasma Treatment

This paper considers the effect of RF plasma on wood in improving the adhesion of binders to wood by increasing its surface wettability. Our study reveals that radiofrequency (RF) plasma treatment causes a greater than threefold decrease in the marginal wetting angle of wood. The greatest effect is achieved in RF plasma treatment in argon, which is on average 5% greater than that of RF plasma treatment in air or in propane/nitrogen mixture. In addition, the power of the RF plasma torch has the greatest influence, and the main influence comes from the voltage applied to the RF plasma torch; current does not have such a significant effect. To achieve a significant effect, the duration of exposure should be at least 5 min, with a total power of 4.05 kW.Studies have been conducted to determine the adhesive strength of wood. An increase in the strength of laminated beams made from RF-treated bars in relation to control samples was found. The greatest impact on the adhesion strength was revealed when using PVA-based glue, compared with the use of polyurethane-based adhesives and urea-formaldehyde resin.

Numerical analysis on evolution process of multiple rotating detonation waves with ethylene–oxygen–nitrogen mixture

Two-dimensional numerical simulations of a rotating detonation combustor (RDC) fueled by ethylene–oxygen–nitrogen were performed to investigate the evolution process of multiple rotating detonation waves (RDWs), that is, initial chaotic stage, self-adjustment stage, and the final stable stage. The number of stable RDWs corresponding to the initial conditions was in good agreement with that predicted by an empirical model proposed by Daniau et al. from Lavrenty’ev Institute of Hydrodynamics (LIH). From the simulation results, the spontaneous formation of a reverse RDW and the transition of trailing waves to detonation waves contribute to the emergence of the chaotic stage. The self-adjustment stage comprises three distinctive parts, which are the self-adjustment of the propagation direction, the number, and the propagation characteristics of RDWs. Furthermore, the double-wave collision was found to play a significant role in modulating the propagation direction as well as the number of RDWs. The same self-adjusting trend of different instantaneous propagation characteristics (e.g., peak pressure, propagation velocity, and wave front height) of the RDWs was observed, suggesting the self-similarity property of the adjusting mechanism demonstrated in the evolution of rotating detonation dynamics.

The Effects of Modifying the Activity of Nitriding Media by Diluting Ammonia with Nitrogen

This paper discusses the issue of the effects of modifying the activity of nitriding media by diluting ammonia with nitrogen and the concomitant variation in the degree of ammonia dissociation on the layer’s growth kinetics and their phase composition. To understand and quantify the effects of the variation in the main parameters that influence the layer growth kinetics, the experimental programming method was used and mathematical models of interactions between influence and kinetics parameters were obtained for two metallic materials: Fe-ARMCO and 34CrAlMo5 nitralloy steel. It was concluded that the nitriding operating temperature and the degree of nitrogen dilution of the ammonia have statistically significant influences on the kinetics of the nitrided layer. In the same context, it was analytically proved and experimentally confirmed that the ammonia degree dissociation from the gaseous ammonia-nitrogen mixture, along with the dilution degree of the medium with nitrogen, significantly influences the nitrogen potential of the gaseous mixture used for nitriding and thus the concentration of nitrogen in balance at the medium thermochemically processed metal product interface.

Генерация тока в структурах Pd/InP в атмосфере водорода

The current generation mechanism in Pd/InP Schottky diodes has been studied in the range of 90−300K in vacuum, hydrogen-nitrogen mixture of concentration from 4 to 100 vol.%, and under illuminating of the structures by LED with the wavelength of 0.9 μm, corresponding to the absorption edge in InP. It was shown that at low temperature (T = 90K) I−V characteristics of the structures in vacuum have rectifying character with the barrier height of 130−150meV. In hydrogen-nitrogen medium the barrier height decreases almost to zero with increasing the temperature to 300K due to palladium work function decreasing. It was demonstrated that under simultaneous impact of illumination (λ = 0.9 μm) and hydrogen-nitrogen mixture there are two opposite directed electron flows in the structures, one of which is related to the LED illumination and the other one to hydrogen absorption in palladium layer.

EXPERIMENTAL STUDY OF FOAMED EMULSION COMBUSTION: EFFECTS OF OXYGEN, DICHLOROETHANE, AND GLYCEROL CONCENTRATIONS

The paper considers experimentally the issue of combustion of foamed emulsions prepared via bubbling of the emulsion with the use of oxygen/nitrogen mixture.

Структурные свойства углеродных пленок, полученных методом ионно-стимулированного импульсно-плазменного осаждения в атмосфере азота

Carbon films were synthesized by pulse-plasma ion-assisted graphite sputtering in the atmosphere of argon-nitrogen mixture. The samples were studied by Raman spectroscopy, electron diffraction and XPS. According to the obtained data, nitrogen efficiently incorporates into the material structure, which leads to the formation of oriented graphite nanoclusters, which fraction reduces with ion assistance energy increase.