Abstract
The method of determination combustion rate of powdered porous silicon with limited space is presented. The values of the combustion rates of porous silicon are close to the values of the rates of explosives.
The method of determination combustion rate of powdered porous silicon with limited space is presented. The values of the combustion rates of porous silicon are close to the values of the rates of explosives.
High crystalline quality epitaxial films of orthorhombic gallium oxide ε(κ)-Ga2O3 with a thickness of more 20 μm have been grown for the first time using halide vapor phase epitaxy. Sapphire wafers with preliminarily deposited GaN layers were used as substrates. The properties of the produced films are studied by X-ray diffraction and electron microscopy. The results are considered an important step towards obtaining thick layers and quasi-bulk ε(κ)-Ga2O3 crystals for practical applications in electronics and sensor technology.
Temperature response of a material to an external electric field is the main method for electrocaloric effect study in ferroelectrics. In this work, for 0.65PbFe2/3W1/3O3–0.35PbTiO3 solid solution as a model object, it is shown that with an increase in the electric field strength, current fomentation effect can occur. It leads to formation of local regions of increased conductivity in the sample. The associated thermal effect have short characteristic times, due to the small volume of the filament. They are comparable to the times of the electrocaloric response of the material, and can lead to significant errors in the detection of the electrocaloric effect.
Current switches based on low-voltage InP heterothyristors with a maximum blocking voltage of 20 V were developed and studied. In current pulse generation mode, the efficient operation of InP heterothyristors with a low-resistance load in the form of a capacitor was demonstrated. It has been shown that the minimum turn-on delay time is about 6 ns at a control current amplitude of 60 mA. The possibility of generating current pulses with a duration of 53–154 ns and amplitudes of 38–130 A was demonstrated when the capacitor values were changed in the range of 56–1000 nF.
We propose an approach for encoding and transmitting information based on the use of a quantum dot laser, which, depending on the injection current, emits either one of two or simultaneously two spectral components, with different wavelengths. When the laser is modulated by current, each lasing line is detected by an independent photodiode, and thus the information is encoded by both the intensity of each line and its wavelength.
We studied the influence of the focused ion beam milling of ridge waveguides on lasing parameters of edge-emitting lasers, based on a separate confinement double heterostructure. It is shown that there are three degrees of influence, according to the etching depth: modification of the waveguide properties only, a decrease in efficiency without changing the threshold current, and a simultaneous deterioration in the threshold current and efficiency with significant modification of the optical characteristics of the laser.
The analysis of the ultraviolet induced transformation of the thermal decomposition spectra of the monomer of the submicrometer layers of polymethylmethacrylate and its composite with fullerene C60 for different fullerene concentrations and irradiation doses has been carried out. Formation of the new decomposition stages in the spectra has been interpreted by the binding between C60 and side ester groups of polymethylmethacrylate.
The mirror type magnetic mass-analyzer axial aberration, caused by ions travelling through the mirror outside the median plane is estimated. A technique for the mass-analyzer acceptance optimization is given.
Study of Ga2O3 deposition by MOVPE using trimethylgallium and oxygen was performed in a wide temperature range. It was found that for Ga2O3 deposition rate vs temperature dependence is very close to the TMGa pyrolysis in nitrogen. Kinetically-limited range for these processes corresponds to 550–700°C, that is 150°C higher, then for GaN deposition in the same reactor.
Single-crystalline α-Cr2O3 layers were synthesized on a sapphire substrate with a basal orientation in a laboratory reactor using ultrasonic-assisted chemical vapor deposition in the temperature range of 700–850°C. The influence of the growth temperature on the structural quality of the layer was studied by X-ray diffraction. At a growth temperature of 800°C, continuous layers with a thickness of about 1 μm were obtained. The layers were transparent in the visible region with a slightly greenish tint and showed some light transmission up to wavelengths of ~350 nm. The full width at half maximum of the rocking curve for reflection 0006 was ~300 arcsec.
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