Several systems in the solid state have been suggested as promising candidates for spin-based quantum information processing. In spite of significant progress during the last decade, there is a ...search for new systems with higher potential D. DiVincenzo, Nat. Mater. 9, 468 (2010). We report that silicon vacancy defects in silicon carbide comprise the technological advantages of semiconductor quantum dots and the unique spin properties of the nitrogen-vacancy defects in diamond. Similar to atoms, the silicon vacancy qubits can be controlled under the double radio-optical resonance conditions, allowing for their selective addressing and manipulation. Furthermore, we reveal their long spin memory using pulsed magnetic resonance technique. All these results make silicon vacancy defects in silicon carbide very attractive for quantum applications.
Ion implantation is a key technology without alternative for doping silicon carbide SiC in the manufacturing processes of SiC devices. SiC technology has a number of distinctive features in ...comparison with Si-ion doping technology. This paper provides a systematic analysis of modern technical solutions aimed at the formation of local doped regions by the method of ion implantation for various purposes for SiC-based high-power electronic devices. The results of research conducted at the St. Petersburg State Electrotechnical University LETI are presented. This research is focused on the development and selection of modes of aluminum- and phosphorus-ion implantation into 4H-SiC structures that provide specified concentrations of doping impurities and geometric dimensions of local ion-doped regions. The developed ion-implantation modes are successfully implemented in the manufacture of samples of high-power 4H-SiC metal–insulator–semiconductor (MIS) transistors with operating voltages of up to 1200 V.
Natural and anthropogenic sources of nitrous oxide were considered, and their contribution to environmental pollution was determined. The effect of N
2
O on Earth’s ozone layer was described. The ...commercial method of production of technical and medical nitrous oxide, based on decomposition of a hot solution of ammonia nitrate, was considered. Application areas of nitrous oxide were described, and examples of its use in organic and inorganic synthesis reactions, as well as in medicine, food industry, and technology were given. Methods employed for neutralizing process gases containing nitrogen oxides, in particular absorption and adsorption methods, were reviewed. Particular attention was paid to catalytic tail gas purification in various industries; high- and low-temperature reduction of N
2
O by natural gas and ammonia were described; analytical review of the literature dedicated to catalytic systems and individual compounds that show activity in the decomposition and reduction of nitrous oxide was provided; and mechanisms of nitrous oxide decomposition over various catalysts were considered.
The possibility to increase the responsivity of 4
H
-SiC
p
+
–
n
–
n
+
-photodiodes by varying the thickness of the
p
+
-epilayer has been studied. It is shown that the thinning of the upper epilayer ...by RIE with the use of metal contacts as a mask makes it possible to control both the maximum responsivity and the spectral dependence of the responsivity of photodiodes and does not lead to degradation of dark electrical characteristics.
Currently, chemical gas deposition is the main method for producing high-quality and reproducible epitaxial layers for commercial silicon carbide (SiC) power devices. Based on the experience of the ...Electrotechnical University LETI in the synthesis of single-crystalline SiC, an analysis of the current state of silicon carbide gas phase epitaxy (CVD) technology is carried out. It is shown that modern CVD reactors allow growth processes of high-quality SiC epitaxial structures with the following parameters: substrate diameter of up to 200 mm; epitaxial layer thicknesses of 0.1 to 250 μm; and
n
- and
p
-type layers with doping levels in the ranges 10
14
–10
19
cm
–3
and 10
14
–10
20
cm
–3
, respectively. At the same time, setting up the technology of the reproducible high-quality growth of epitaxial layers is an individual task for a particular type of reactor. A detailed consideration of the technological factors presented in this paper is required, which in the end determine the achievable parameters of SiC-epitaxial products.
•Retention additivity of diarylphthalides, diaryl(arylene)phthalides and diaryldiphthalides is conditioned by structural additivity of these compounds.•The retention times of congeners correlate with ...the total partial charge on oxygen and sulfur atoms in heteroaromatic fragments.•Conformationally flexible meso and chiral diastereoisomers of diaryl(arylene)phthalides in the chromatograms elute with one peak.•The chiral diastereoisomers of sterically hindered diaryldiphthalides are retained longer than the meso-isomers.•In a row of chiral diaryldiphthalides enantiomers with the shorter positive cotton effect are the first to elute.
For the first time, four series of new phthalide-containing heteroaromatic compounds were separated by reverse phase HPLC: OYO, OYS, SYS; OYOYO, OYOYS, SYOYS; SYSYS, SYSYO, OYSYO; OYYO, OYYS, SYYS, (where O – diphenyloxide, S – diphenylsulfide, Y – phthalide group). A fundamental difference was established in the chromatographic behavior of diaryl(arylene)diphthalides, built on the principle of “head-to-tail”, and diaryldiphthalides with a structure of “head-to-head”. The meso and chiral diastereoisomers of the former were eluted by one peak, while the latter existed in solution in the forms of stable cis (racemic form) and trans (meso form) rotamers with different retention times. It was shown that to calculate the retention times of related diarylphthalides, diaryl(arylene)phthalides, diastereoisomeric and enantiomeric diaryldiphthalides of an asymmetric structure, the half-sum rule can be applied according to which: tR(A-X-B)≈(tR(A-X-A)+tR(B-X-B)/2. For diaryl(arylene)diphthalides of a triadic structure, a modified additive scheme for calculating retention times is proposed, including multiplication and division operations: tR(A-A-A) = tR(A-A-B) × tR(A-B-B)/tR(B-B-B).
A spatially distributed chirp ionosonde records signals scattered by the Earth’s surface at long distances from the emitter, even with relatively low transmitter powers. Experimental studies of the ...ionosphere backscatter sounding (BS) based on the multifunctional chirp ionosonde developed at the Institute of Solar–Terrestrial Physics of the Siberian Branch of the Russian Academy of Sciences (ISTP SB RAS) have revealed the potential of such systems for diagnosing the propagation medium. With a transmitter power of a few kilowatts, it is possible to obtain high-quality BS ionograms within the maximum single-hop range (3000–4000 km). For the analysis of experimental data, algorithms for calculating the characteristics of BS signals, including the amplitude sweep of the recorded signal, are developed. Methods for diagnosing the decameter radio channel using BS data, which are based on the extraction of the leading edge of the BS signal during the processing and interpretation of ionograms, are elaborated. The results of extraction of the signal leading edge on the ionogram are used to calculate the maximum usable frequencies and characteristics of the oblique propagation trajectories for given radio paths in the sounding sector. Algorithms for inversion of the leading edge of the BS signal into the electron density are implemented.
A technique has been developed for frequency analysis of the IR reflection spectrum to determine the thickness and order of the layers in the epitaxial structure of silicon carbide. Calculations for ...the 4
H
-SiC epitaxial structure have been performed. The method has been shown to be highly sensitive to optical boundaries resulting from a sequential increase in the doping level during the layer growth.
The article discusses the possibility of using silicone lacquer as a masking coating when creating micro-dimensional mesa structures on the 4H-SiC surface using the reactive ion-plasma etching ...method. The etching process was carried out on a setup with an ICP plasma source. The experiments were performed with the aim of determining the dependence of the angle of inclination of the wall of the mesa structure on the parameters of the etching process. The etching results were recorded with a Helius nanolab instrument complex and a Quanta Inspec raster electron microscope.
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