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Carrier lifetime in low carrier concentration 4H-SiC epitaxial layers grown on the C-face was enhanced by using carbon implantation and post annealing. The measured carrier lifetime increased with the thickness of the epitaxial layer and was 11.4 µs for the 150 µm thick epitaxial layer. The internal carrier lifetime was estimated as 21 µs from the dependence of the measured carrier lifetime on the epitaxial layer thickness. This value is almost comparable to the reported values of the internal carrier lifetime for the layers grown on the Si-face.

The article is devoted to the study of various solvents influence on the quality of epitaxial layers A4B6 type semiconductor compounds growing during liquid-phase epitaxy. The choice of such compounds was primarily due to the instrumental characteristics of the obtained structures based on lead-tin chalcogenides, which are competitive in comparison with A2B6, among which there are significant sensitivity, response speed, thermal and radiation resistance, spectral homogeneity, and low noise level. The use of multicomponent heterolayers of the Pb1 – xSnxTe1 – ySey type makes it possible, by changing the composition, to control the band gap and, within certain limits, to match the parameters of the substrate and the epitaxial layer crystal lattices. In addition, such advantages of liquid-phase epitaxy as low growth temperatures, relatively simple equipment, short duration and cost of the processes, make it possible to continue research in the above direction.The analysis of the possibility of using In, Ga, Cd, Te, Bi and other solvent metals as alternatives to lead for growing by liquid epitaxy of solid solutions in the Pb-Sn-Te-Se system has been carried out. The use of only solvents based on Te, Tl, Bi in experimental studies is substantiated. In particular, the epitaxial growing with a tellurium solvent demonstrated that use of Bi (for concentrations of 50 atomic %) significantly affected not only the removal of the growth melt, but also the morphology of the grown layers: the surface was free from the wavy relief inherent in epitaxial layers grown from pure tellurium solutions-melts. The results show the promise of Bi-Te melt solutions using, which make it possible to obtain structurally perfect epitaxial layers of n-type conductivity with a dislocation density of ~10 5cm – 2, a carrier concentration of ~10 18cm – 3 and a mobility of (103 -104) cm2/Vs at 77K.

Advances towards achieving the goal of miniature 4H-SiC based radiation detectors for harsh environment application have been studied extensively and reviewed in this article. The miniaturized devices were developed at the University of South Carolina (UofSC) on 8 × 8 mm 4H-SiC epitaxial layer wafers with an active area of ≈11 mm2. The thicknesses of the actual epitaxial layers were either 20 or 50 µm. The article reviews the investigation of defect levels in 4H-SiC epilayers and radiation detection properties of Schottky barrier devices (SBDs) fabricated in our laboratories at UofSC. Our studies led to the development of miniature SBDs with superior quality radiation detectors with highest reported energy resolution for alpha particles. The primary findings of this article shed light on defect identification in 4H-SiC epilayers and their correlation with the radiation detection properties.

A search for an optimum technique for studying the electrical characteristics of thin n/p-InxGa1–xAs semiconductor layers with different doping levels has been carried out. The primary task has been to measure the main electrical characteristics by different methods using resistivity (conductivity), majority carrier concentration, dependence of the main electrical parameters on the doping type and level, and their comparison. Using the example of the p- and n-In0.01Ga0.99As solid solutions grown by MOCVD, a technique for studying the main electrical characteristics of the epitaxial layers has been proposed, which takes into account the estimated homogeneity on large-area samples. Results obtained by different methods, including photoluminescence, contactless surface resistivity measurement, van der Pauw (Hall effect), electrochemical capacitance–voltage profiling, and in situ control, have been compared. Basing on the results obtained and comparison with the literature data, conclusions have been drawn concerning the need, sufficiency, and complementarity of the methods for controlling and studying semiconductor epitaxial structures.

The effect of beryllium co-doping on the magnetoresistance anisotropy in the GaMnAs layer grown via lowtemperature molecular beam epitaxy is investigated in this paper. The magnetoresistance anisotropy is observed in the GaMnAs:Be epilayer in the range of fields up to 2000 Oe along [110] and [1͞10] crystalligraphic axes. This anisotropy manifests itself in the different behavior of the temperature dependence of magnetoresistance and can result from the formation of spatially oriented structures in the GaMnAs epilayer, which emerge in the bulk of this layer during its growth.

In this study, we grew homoepitaxial layers on 3-inch on-axis carbon-face 4H-silicon carbide substrates and attempted to suppress the generation of 3C-inclusions. It was found that the 3C-inclusion density decreased with increasing time spent on reaching an objective flow rate for the precursors. It is suggested that 3C-SiC nucleation occurred on large terraces of the on-axis substrates, which existed before the substrates were covered with spiral hillocks. This nucleation was suppressed owing to the decrease in the degree of supersaturation at the initial growth stage. Moreover, we found that the 3C-inclusions were also generated owing to contamination in the form of graphite products. Furthermore, we succeeded in growing a thick on-axis 4H-SiC homoepitaxial layer on a 3-inch substrate and demonstrating its free-standing epitaxial layer with a thickness of 182 μm and a 3C-inclusion density of 2.0 cm−2.

Step bunching on a vicinal 4H-SiC (0001) epitaxial layer surface was investigated using low-voltage scanning electron microscopy (LVSEM) and low-energy electron channeling contrast (ECC) imaging. LVSEM observations revealed that the step bunching resulted in the formation of atomically flat wide (~250 nm) terraces on the surface, and the terraces tended to form in pairs. The two terraces in paired terraces often showed the same electron channeling contrast as each other, and the contrast of the two terraces, either bright or dark, appeared to be determined by the orthogonal misorientation of substrates. On the basis of these results, the formation mechanism of the step-bunched structure on a vicinal 4H-SiC (0001) surface is discussed.

The energy spectra of growth traps in the epitaxial layers of undoped and doped gallium nitride grown under various technological conditions are analyzed. Keywords: GaN epitaxial layers, growth traps.

The resonant frequency and Q factor of the SiC microcantilever were theoretically analyzed and calculated based on the stereotyped basic theories of the cantilever beam, and the relationship between the vibration mode and structure geometries was also simulated. Modal analysis by means of finite element method was performed on millimeter-, micron-and nanoscale microcantilevers, and the results showed that the smaller the microstructure was, the higher the resonant frequency can be obtained. The Q factor can be extracted from hamonic spectra after modal analysis, and the amplitude of Q factor was about 105. This paper shows that SiC epitaxial layers have great potential in microcantilevers.

Ridge low loss (0.16±0.02 dB/cm) waveguides were fabricated in Pr,Gd:LiYF4 epitaxial layers by precision diamond-saw dicing. The red waveguide laser generated 504 mW at 639.7 nm with a slope efficiency of 57.8%, a linear polarization and a laser threshold of 34 mW. Laser operation in the orange and deep red was also demonstrated.