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Availability of high-quality, large diameter SiC wafers in quantity has bolstered the commercial application of and interest in both SiC- and nitride-based device technologies. Successful development of SiC devices requires low defect densities, which have been achieved only through significant advances in substrate and epitaxial layer quality. Cree has established viable materials technologies to attain these qualities on production wafers and further developments are imminent. Zero micropipe (ZMP) 100 mm 4HN-SiC substrates are commercially available and 1c dislocations densities were reduced to values as low as 175 cm-2. On these low defect substrates we have achieved repeatable production of thick epitaxial layers with defect densities of less than 1 cm-2 and as low as 0.2 cm-2. These accomplishments rely on precise monitoring of both material and manufacturing induced defects. Selective etch techniques and an optical surface analyzer is used to inspect these defects on our wafers. Results were verified by optical microscopy and x-ray topography.

DC characteristics and reverse recovery performance of 4H-SiC Junction Barrier Schottky (JBS) diodes capable of blocking in excess of 10 kV with forward conduction of 20 A at a forward voltage of less than 4 V are described. Performance comparisons are made to a similarly rated 10 kV 4H-SiC PiN diode. The JBS diodes show a significant improvement in reverse recovery stored charge as compared to PiN diodes, showing half of the stored charge at 25°C and a quarter of the stored charge at 125°C when switched to 3 kV blocking. These large area JBS diodes were also employed to demonstrate the tremendous advances that have recently been made in 4H-SiC substrate quality.

Recent advances in PVT c-axis growth process have shown a path for eliminating micropipes in 4HN-SiC, leading to the demonstration of zero micropipe density 100 mm 4HN-SiC wafers. Combined techniques of KOH etching and cross-polarizer inspections were used to confirm the absence of micropipes. Crystal growth studies for 3-inch material with similar processes have demonstrated a 1c screw dislocation median density of 175 cm-2, compared to typical densities of 2x103 to 4x103 cm-2 in current production wafers. These values were obtained through optical scanning analyzer methods and verified by x-ray topography.

We review the progress in the industrial production of SiC substrates and epitaxial layers for high power semiconductor devices. Optimization of SiC bulk growth by the sublimation method has resulted in the commercial release of 100 mm n -type 4H-SiC wafers and the demonstration of micropipe densities as low as 0.7 cm−2 over a full 100 mm diameter. Modelling results link the formation of basal plane dislocations in SiC crystals to thermoelastic stress during growth. A warm-wall planetary SiC-VPE reactor has been optimized up to a 8×100 mm configuration for the growth of uniform 0.01–80-micron thick, specular, device-quality SiC epitaxial layers with low background doping concentrations of p - and n -type doping from ∼1×1015 to >1×1019 cm−3. We address the observed degradation of the forward characteristics of bipolar SiC PiN diodes [H. Lendenmann, F. Dahlquist, J.P. Bergmann, H. Bleichner, C. Hallin, Mater. Sci. Forum 389–393 (2002) 1259], and discuss the underlying mechanism due to stacking fault formation in the epitaxial layers. A process for the growth of the epitaxial layers with a basal plane dislocation density

In recent years SiC has metamorphisized from an R&D based materials system to emerge as a key substrate technology for a significant fraction of the world production of green, blue and ultraviolet LEDs. Emerging markets for SiC homoepitaxy include high-power switching devices and microwave devices. Applications for heteroepitaxial GaN-based structures on SiC substrates include lasers and microwave devices. In this paper we review the properties of SiC, assess the current status of substrate and epitaxial growth, and outline our expectations for SiC in the future.

The current status of SiC bulk growth is reviewed, while specific attention is given to the effect of defects in SiC substrates and epitaxial layers on device performance and yield. The progress in SiC wafer quality is reflected in the achievement of micropipe densities as low as 0.92 cm−2 for a 3-inch n-type 4H-SiC wafer, which provides the basis for a high yielding fabrication process of large area SiC power devices. Using a Murphy Probe Yield Analysis for the breakdown characteristics of 10 kV PiN diodes we have extracted an “effective” defect density for 4H-SiC material to be as low as 30 cm−2, providing valuable information to further isolate and address the specific material defects critical for device performance. We address the problematic degradation of the forward characteristics (V f -drift) of bipolar SiC PiN diodes [CITE]. The underlying mechanism due to stacking fault formation in the epitaxial layers and possible effects of device processing are investigated. An improved device design is demonstrated, which effectively stabilizes this V f -drift. We show the progression in the development of semi-insulating SiC grown by the sublimation technique from extrinsically doped material to high purity semi-insulating (HPSI) 4H-SiC bulk crystals of up to 100 mm diameter without resorting to the intentional introduction of elemental deep level dopants, such as vanadium. Uniform resistivities in 3-inch HPSI wafers greater than 3 × 1011 Ω-cm have been achieved. Secondary ion mass spectrometry, deep level transient spectroscopy and electron paramagnetic resonance data suggest that the semi-insulating behavior in HPSI material originates from deep levels associated with intrinsic point defects. MESFETs produced on HPSI wafers are free of backgating effects and have resulted in the best combination of power density and efficiency reported to date for SiC MESFETs of 5.2 W/mm and 63% power added efficiency (PAE) at 3.5 GHz.

The growth of high-purity, semi-insulating (HPSI) 4H-SiC crystals has been achieved using the seeded-sublimation growth technique. These semi-insulating (SI) crystals (2-inch diameter) were produced without the intentional introduction of elemental deep-level dopants, such as vanadium, and wafers cut from these crystals possess room-temperature resistivities greater than 109 Ωcm. Based upon temperature-dependent resistivity measurements, the SI behavior is characterized by several activation energies ranging from 0.9-1.5 eV. Secondary ion mass spectroscopy (SIMS) and electron paramagnetic resonance (EPR) data suggest that the SI behavior originates from deep levels associated with intrinsic point defects. Typical micropipe densities for wafers were between 30 cm-2 and 150 cm-2. The room-temperature thermal conductivity of this material is near the theoretical maximum of 5 W/mK for 4H-SiC, making these wafers suitable for high-power microwave applications.

An intrinsic defect (ID) has been identified in as-grown 4H–SiC by electron paramagnetic resonance (EPR). The EPR parameters of an ID measured in our nominally semi-insulating material are similar to the literature data of the EI5 defect produced in p-type 4H and 6H–SiC by 2.5 MeV electrons and assigned to the carbon vacancy (N.T. Son, P.N. Hai, E. Jansen, Phys. Rev. B 63 (2000) 201201). However, comparison of the ID and EI5 centers reveals that the as-grown and radiation-induced centers exhibit different annealing behavior. Photo-induced EPR locates the ID level 0.9 eV above the valence band edge.

The production of large diameter, high quality SiC substrates is essential to realize the full potential of this important semiconductor material. The current status of SiC bulk sublimation growth for the production of these substrates is reviewed from an industrial point of view. Specific efforts towards larger diameter high quality substrates have led to the production of 50 and 75 mm diameter 4H and 6H wafers and the demonstration of high quality 100-mm wafers. We present thermal conductivity data for material of different doping levels, relevant for device applications. In SiC, micropipes are the most harmful defects for SiC device production. By continuous optimization of the growth process we were able to steadily decrease the micropipe density over the past several years, down to densities as low as 1.1 cm −2 for an entire 50-mm wafer, indicating that micropipes may be totally eliminated in the next few years. In order to achieve this goal for SiC substrates of increasing diameter, a thorough understanding of the growth process is essential. We will summarize results of modeling the growth process and its experimental verification. The effect of micropipe densities and their characteristic lateral distribution in SiC wafers on achievable device yields will be discussed, using large area Schottky diodes as an example.

Silicon-carbide-based device technology as well as the volume production of nitride-based, high brightness blue and green LEDs fabricated on SiC substrates has made tremendous progress within the last several years. The commercial availability of large, high-quality SiC substrates is a key issue for the realization of the full potential of this technology. The current status of SiC bulk sublimation growth for the industrial production of 50 mm diameter 4H and 6H wafers and the quality improvement of 75 mm wafers is reviewed. Results at Cree show a continous reduction of the micropipe density in SiC substrates, demonstrating micropipe free material of a 25 mm diameter and densities as low as 1.1 cm −2 for an entire 50 mm 4H–SiC wafer. We present results of modeling the relevant heat transfer processes during crystal growth and the thermoelastic stress in the growing crystal. The effect on dislocation generation is discussed. The recent interest in SiC for the production of a unique gemstone material (moissanite) additionally increases the demand for high-quality SiC bulk material.

Silicon carbide technology has made tremendous strides in the last several years, with a variety of encouraging device and circuit demonstrations in addition to volume production of nitride-based blue LEDs being fabricated on SiC substrates. The commercial availability of relatively large, high quality wafers of the 6H and 4H polytypes of SiC for device development has facilitated these exciting breakthroughs in laboratories throughout the world. These have occurred in numerous application areas, including high power devices, short wavelength optoelectronic devices, and high power/high frequency devices. This paper will describe progress made in increasing the quality and size of SiC wafers, advances in SiC epitaxy and some of the resulting device demonstrations and commercialization by Cree Research.

Hollow-core screw dislocations, also known as “micropipes”, along the [0001] axis in 6H-SiC single crystals, have been studied by synchrotron white beam x-ray topography (SWBXT), scanning electron microscopy (SEM), and Nomarski optical microscopy (NOM). Using SWBXT, the magnitude of the Burgers vector of screw dislocations has been determined by measuring the following four parameters: (1) the diameter of dislocation images in back-reflection topographs; (2) the width of bimodal dislocation images in transmission topographs; (3) the magnitude of the tilt of lattice planes on both sides of dislocation core in projection topographs; and (4) the magnitude of the tilt of lattice planes in section topographs. The four methods show good agreement. SEM results reveal that micropipes emerge as holes on the as-grown surface, with their diameters ranging from about 0.1 to a few micrometers. Correlation between topographic images and SEM micrographs shows that micropipes are hollow-core screw dislocations with Burgers vector magnitudes from 2c to 7c (c is the lattice parameter along the [0001] axis). There is no empirical evidence that 1c dislocations have hollow cores. The Burgers vector magnitude of screw disloca-tions, b, and the diameter of associated micropipes, D, were fitted to Frank’s prediction for hollow-core screw dislocations: D = μb2/4π2γ, where μ is shear modulus, and γ is specific surface energy. Statistical analysis of the relationship between D and b2 shows that it is approximately linear, and the constant γ/μ ranges from 1.1 × 10−3 to 1.6 × l0−3 nm.

Screw dislocations along the [0001] axis in 6H−SiC single crystals have been studied extensively by Synchrotron White-Beam X-ray Topography (SWBXT), Scanning Electron Microscopy (SEM), and Nomarski Optical Microscopy (NOM). Using SWBXT, the magnitude of the Burgers vector of screw dislocations has been determined by measuring the following four parameters: 1) the diameter of dislocation images in back-reflection topographs; 2) the width of bimodal dislocation images in transmission topographs; 3) the magnitude of the tilt of lattice planes on both sides of dislocation core in projection topographs; and 4) the magnitude of the tilt of lattice planes in section topographs. The four methods show good agreement. SEM results reveal that micropipes in the form of hollow tubes run through the crystal emerging as holes on the as-grown surface, with their diameters ranging from about 0.1 to a few micrometers. Correlation between topographic images and SEM micrographs shows that micropipes are screw dislocations with Burgers vector magnitudes from 2c to 7c (c is the lattice constant along the [0001] axis). There isno were fitted to Frank’s prediction for hollow-core screw dislocations:D =μb2/4π 2 γ, where μ is the shear modulus, and γ is the specific surface energy. Statistical analysis of the relationship betweenD and b2 shows that it is approximately linear, and the constant, γ/μ, obtained from the slope, ranges from 1.1×10−3 to 1.6×10−3 nm.

A dispersed clay/polymer nanocomposite was prepared by joining, via a cationic exchange reaction, surfactant monomers to clay platelets and subsequently polymerizing them with acrylamide. Dispersion was made possible by preparing a clay surfactant precursor solution, with the surfactant in sufficient excess to form clay-micelle complexes that resist platelet aggregation. This homogeneous nanoscale dispersion of platelets was verified using dynamic light scattering.

Synchrotron white-beam X-ray topography studies, in conjunction with Nomarski optical microscopy, have been carried out on 6H-SiC single crystals grown by the sublimation physical vapour transport technique. Two kinds of dislocations were observed using topography: dislocations exhibiting bimodal images of various widths and with line directions approximately parallel to the (0001) axis and dislocations confined to the basal plane, which appear to have emanated from the former dislocations. The larger bimodal image width dislocations were found to have hollow cores, known as 'micropipes'. Detailed contrast analysis of topographic images obtained in transmission and back-reflection geometries establishes that 'micropipes' are Frank-type hollow-core screw dislocations with Burgers vectors typically equal to 3-7 times the c lattice parameter. X-ray topography also revealed many line defects approximately parallel to the (0001) axis that were determined to be screw dislocations with Burgers vectors equal to the c lattice parameter and there were no discernible 'micropipes' associated with these latter screw dislocations.

HPLC columns were packed with quasi-spherical montmorillonite particles which were prepared by spray-drying and then thermally treated. Separations of phenylureas (linuron, neburon, diuron and monuron), phosphothioate phenyl esters (parathion, methyl parathion and paraoxon) and other smaller substituted benzenes were performed on the columns. The relative retention of the substituted phenyl pesticides demonstrated the important role polar substituents play in the eluate-surface interactions and the strong influence of steric factors on these interactions. The retention of the pesticides decreased sharply as the polarity of the mobile phase increased. The retention of the smaller substituted benzenes showed a similar trend, but for these smaller molecules this trend was partially counteracted by the increased accessibility of interlayer spaces due to swelling as the polarity of the liquid phase increased. The role of the exchangeable cation (Na+, Co2+ and Cu2+) in the adsorption was found to be complex. The cations determine both the strength of interaction, which increases with the valence of the cation, and the accessibility of the interlayer adsorption sites which decreased with the valence.

A thermal anneal process has been developed that significantly enhances minority carrier lifetime (MCL) in bulk-grown substrates. Microwave photoconductivity decay (MPCD) measurements on bulk grown substrates subjected to this process have exhibited decay times in excess of 35 μs. Electron Beam Induced Current (EBIC) measurements indicated a minority carrier diffusion length (MCDL) of 65 μm resulting in a calculated MCL of 15 μs, well within the range of that measured by MPCD. Deep level transient spectroscopic (DLTS) analysis of samples subjected to this anneal process indicated that a significant reduction of deep level defects, particularly Z1/2, may account for the significantly enhanced lifetimes. The enhanced lifetime is coincident with a transformation of the original as-grown crystal into a strained or disordered lattice configuration as a result of the high temperature anneal process. PiN diodes were fabricated employing 350 μm thick bulk-grown substrates as the intrinsic drift region and thin p- and n-type epitaxial layers on either face of the substrate to act as the anode and cathode, respectively. Conductivity modulation was achieved in these diodes with a 10x effective carrier concentration increase over the background doping as extracted from the differential on-resistance. Significant stacking fault generation observed during forward operation served as additional evidence of conductivity modulation and underscores the importance of reducing dislocation densities in substrates in order to produce a viable bulk-grown drift layer.

The performance enhancements offered by the next generation of SiC high power devices offer potential for enormous growth in SiC power device markets in the next few years. For this growth to occur, it is imperative that substrate and epitaxial material quality increases to meet the needs of the targeted applications. We will discuss the status and requirements for SiC substrates and epitaxial material for power devices such as Schottky and PiN diodes. For the SiC Schottky device where current production is approaching 50 amp devices, there are several material aspects that are key. These include; wafer diameter (3-inch and 100-mm), micropipe density (−2 for 3-inch substrates and 16 cm−2 for 100-mm substrates), epitaxial defect densities (total electrically active defects −2), epitaxial doping and epitaxial thickness uniformity. For the PiN diodes the major challenge is the degradation of the Vf characteristics due to the introduction of stacking faults during the device operation. We have demonstrated that the stacking faults are often generated from basal plane dislocations in the active region of the device. Additionally we have demonstrated that by reducing the basal plane dislocation density, stable PiN diodes can be produced. At present typical basal plane dislocation densities in our epitaxial layers are 100 to 500 cm−2; however, we have achieved basal plane dislocation densities as low as 4 cm−2 in epitaxial layers grown on 8° off-axis 4H-SiC substrates.

MESFET's fabricated on high resistivity 4H-SiC substrates have attained an f/sub max/ of 30.5 GHz and an f/sub /spl tau// of 14.0 GHz. Both of these figures of merit are the highest ever reported for a SiC MESFET, and this is the first report of high resistivity 4H-SiC substrates. With the continued advances in bulk crystal growth, including the availability of high resistivity material, the development of two-inch substrates and the reduction of micropipe defect densities to

Publisher Summary During the past decade, silicon carbide (SiC) semiconductor device technology for electronic and optoelectronic applications has made tremendous progress resulting primarily from the commercial availability of SiC substrates of ever increasing diameter and quality. Throughout the technical evolution of semiconductor SiC, the fabrication of SiC crystals exhibiting the desired electrical and crystalline properties has played a central role in the realization of the full potential of this important semiconductor material. The aim of this chapter is to discuss, from an industrial viewpoint, the current state of SiC crystal growth technology and to present empirical results that reflect the recent advances in SiC crystal growth. Recent progress in the development of the physical vapor transport (PVT) technique for SiC bulk growth has led to substrate diameters up to 100-mm, residual impurities in the lO15 cm-3 range, thermal conductivity approaching 5.0 W/cmK in bulk crystals, transparent 6H and 4H-SiC at crystal diameters up to 75-mm, and micropipe densities as low as 0.9 cm-2 over a 50-mm diameter 4H-SiC wafer. These advances help to position SiC for an exciting future and provide a sound foundation for the realization of the full potential of SiC for high power density electronic devices, optoelectronic devices of high brightness, and SiC materials applications requiring low optical absorption.

The production of large diameter, high quality boules of SiC is essential to realize the full potential of this important semiconductor material. The objective of this paper is to provide a state-of-the-art analysis of the key directions for SiC bulk growth research, as well as presenting our most recent empirical results. Based on an analytical review of current knowledge, the following topics concerning growth of large 6H and 4H-SiC bulk crystals are discussed: 1) thermodynamics of the vapor phase including the efficiency of crystal growth, 2) kinetics of growth including mass transport in the boundary layer and 3) defect formation processes including thermoelastic stress. In addition, results of growth modeling are summarized and direction for further work suggested. Results on growth of semi-insulating and 50–75 mm diameter 4H-SiC wafers are presented. A discussion on micropipes, which are currently the most harmful defect in SiC wafers is presented. Although several mechanisms, or combinations of mechanisms, cause micropipes in SiC boules grown by the seeded sublimation method, we have reduced micropipe densities by orders of magnitude over the last few years. This continual reduction and the production of wafers with micropipe densities of less than 1 cm-2 (with >1 cm2 areas void of micropipes), indicate that micropipes will be reduced to a level that makes high current devices viable and that they may soon be totally eliminated.

Synchrotron white beam X-ray topography, along with optical microscopy and scanning electron microscopy, has been used to characterize structural defects which are potentially detrimental to device performance in PVT 6H-SiC single crystals. Line defects running along the [0001] axis, known as “micropipes”, were studied extensively. Detailed analysis of topographic image contrast associated with “micropipes”, based on the kinematical theory of X-ray diffraction, established that the so-called “micropipes” are screw dislocations with large Burgers vectors.

The year 1990 marked the 35th anniversary of the publishing of the work of Lely [1] in which the growth of semiconducting silicon carbide single crystals by spontaneous crystallization from the vapor at 2550–2600 ¼ was reported. During these years, numerous attempts have been made to perfect the method by optimizing the thermal fields in the growth zone and controlling crystal nucleation by adding perforated graphite crystallization inserts and seed crystals to the growth zone (see a previous review [2]). Nevertheless, the principal drawbacks of this method have not been overcome. These include the high temperatures, the poor control of the nucleation, the small crystal sizes, the inability to control their shape (faceted plates grow), the inability to control production of various polytypes, and the uneven doping and dislocation distribution in the crystals grown. Therefore, alternative methods for growing silicon carbide crystals have been under development. A thermodynamic analysis of the growth of SiC single crystals from the melt demonstrated that the SiC melt itself can exist at temperatures greater than 3460 K and pressures greater than 104 MPa. This has not yet enabled the well-developed methods for growing crystals from their own melts to be used to prepare bulk SiC single crystals. Our investigations have revealed a low efficiency of the processes for growing bulk SiC single crystals from fluxes, a serious problem with the choice of crucible materials for holding the reaction melts, a substantial entrainment of solvent by the growing crystal, etc.

A retrospective analysis was made of the diagnostic period of Crohn's disease as well as of x-ray and endoscopic signs in 28 patients. Three forms of the disease were distinguished: acute (pseudoappendicular), stenosing with chronic intestinal obstruction syndrome and primary chronic characterized by the triad (pains in the stomach, diarrhea, fever) or by the syndrome of malabsorption with extraintestinal manifestations. In the stenosing and primary chronic forms of Crohn's disease, a correct diagnosis was established in the majority of the patients 3-5 years after appearance of the symptoms. To improve early diagnosis of Crohn's disease, it is recommended that indications for x-ray and endoscopic examinations be extended. These examinations are indicated in all the patients with recurrent pains in the right iliac area, fever of obscure genesis and chronic diarrhea.

The authors describe some features of x-ray symptoms of Gee-Herter disease with relation to severity and a period of disease. Altogether 106 adult patients with this disease were followed up, of them 78 patients with diagnosis of Gee-Herter disease, confirmed by histology of intestinal biopsy specimens, were selected for analysis. Three groups of patients with different x-ray symptoms were singled out. Some distinctive features of differential diagnosis and complications of Gee-Herter disease in adults were noted.

The authors observed 10 patients with malignant lymphoma revealed by x-ray; 2 of them were supposed to be afflicted with heavy alpha-chain disease with malignant transformation. An x-ray picture revealed a triad of pathognomonic symptoms and a regular parallelism of intestinal changes with clinico-laboratory findings. In all the cases the diagnosis was confirmed by morphological data.

The authors observed 10 patients with malignant lymphoma revealed by x-ray; 2 of them were supposed to be afflicted with heavy alpha-chain disease with malignant transformation. An x-ray picture revealed a triad of pathognomonic symptoms and a regular parallelism of intestinal changes with clinicolaboratory findings. In all the cases the diagnosis was confirmed by morphological data.

We present results of a thermal anneal process that increases the minority carrier lifetime in SiC substrates to in excess of 3μs, compared to the starting as-grown substrates with lifetimes typically in the

The thermodynamic analysis of high temperature processes in the SiC-N 2 system has been carried out at different initial pressures of nitrogen in the closed system 4, 200, 400, 600, 760, 1140 and 1520 Torr in the temperature interval (1500–3000) K. On the basis of thermodynamic analysis data it has been established that the stoichiometric relationship of silicon and carbon containing components in the vapour phase greatly depends on nitrogen pressure and temperature and this dependence is to be taken into account when analysing the phenomena of luminescence and polytypism in the course of growing silicon carbide monocrystals and epitaxial layers from the vapour phase. The “extent of development” of silicon carbide/nitrogen interaction reactions has been estimated and it has been shown that to certain temperatures (which depend on initial nitrogen pressure i P N 2 and shift toward higher temperatures under the increase of i P N 2 ) it is most likely the reaction, accompanied by the formation of liquid silicon and gaseous cyanogen.

The results of the study of SiC epitaxial layer growth kinetics in the system SiC-C are reported. The effects of temperature, pressure and heterogeneous reactions during the epitaxial layer formation have been studied in vacuum and at different partial pressures of argon in the system. An analysis of the experimental results was made on the basis of the theory of mass transfer by diffusion, taking into consideration the surface reactions. The dependence of the total supersaturation on the velocity of the epitaxial layer growth has been proposed. It has been established that above a certain pressures of argon in the system, and depending on the temperature of growth, the process is controlled primarily by mass transfer by diffusion, while at lower pressures the heterogeneous surface processes influence the kinetics of growth.

The concentrations of clusters of various size in the atmosphere during silicon carbide crystal growth have been calculated on the basis of fundamental ideas of homogeneous nucleation theory, taking into account the specific parameters of silicon carbide. It has been shown that the cluster concentration are sufficiently high to conclude that this is the dominant influence during the initial stages of crystal growth. In this way the assumption of the polymer theory of polytypism, namely that the polytype properties of silicon carbide can be determined from the composition of the gas phase, containing sufficiently large clusters with various polytype structures, has been confirmed.

A method to determine temperature gradient and distribution in high-temperature furnaces for silicon carbide monocrystal and epitaxial layer growing is suggested on the basis of the results obtained from the experiments on silicon carbide epitaxial layer growing kinetics in gas using 2 „sandwiches”. Russian Text Ignored.

As a result of investigation performed, the possibility of producing silicon carbide single-crystalline ingots grown from seeds in the 1800 to 2600°C range has been established. Silicon carbide single crystal growth in vacuum has been shown to be very promising at low temperatures.

High-pressure liquid chromatography columns were packed with quasi-spherical particles of bentonite (SP-bentonite) which were prepared from a predominantly Na-bentonite powder by spray drying. The strength of adsorption of ring-substituted dimethylanilines on bentonite was directly related to their basicity (pKa). The adsorption of the amino-substituted N, N-dimethylaniline was commonly much weaker than that predicted from its pKa, suggesting that the amino group was the dominant site of interaction between the substituted anilines and the clay.

A calculation of the temperature field and radiant and convective components of the thermal flux density is performed for combined action of convection and radiation in a dusty gaseous medium.

On the basis of the epitaxial layers of SiC (N) grown from vapour phase by the sublimation method in a temperature interval (1900–2200) °C and at nitrogen partial pressures from 4 to 760 Torr has been determined the dependence of the nitrogen content in the epitaxial layers of SiC(N) on the nitrogen partial pressure and the temperature of growing. A thermodynamics analysis of the nitrogen solubility process in silicon carbide has been developed taking account of the electron-hole interaction. The experimental and calculation results, we have obtained, allowed us to determine the partial mol solubility heat of nitrogen in SiC. [Russian Text Ignored.]