The paper studies peculiarities of current transport in Au/Pt/Ni/diamond Schottky diodes with the hysteresis in current–voltage (I-V) characteristics and the nonlinear dependence of the barrier height φb on the applied voltage and proposes a method for determining basic parameters. Lateral diode structures were processed on boron-doped HPHT-diamond grown in the Fe-Al-B-C system and demonstrated barrier I-V characteristics with the exponential growth of the forward current of about eight orders of magnitude. It is shown that the voltage-dependent barrier height and hysteresis of the current-voltage characteristics can be explained by the presence of a thin dielectric gap at the metal-semiconductor interface and deep levels with lifetimes of the order of tens of seconds or more. Recharging of deep levels can significantly affect the parameters of the current-voltage characteristics. Three distinct regions were revealed. Excess current at zero voltage (region I) is related to deep-level recharge. Within regions II and III linear dependence of the φb on the applied voltage was observed. A linear dependence of the φb is related to the thermionic-field emission mechanism of current transport. Analysis of the temperature dependence I-V characteristics, capacitance-voltage (С-V) as well as frequency-capacitance (C-f) characteristics of arrays of HPHT diamond Schottky diodes yields information on the distribution of macro-defects, the state of the surface, and doping of the sub-surface region, which can be used for the improvement of the growth process and post-growth treatments for the development of diamond-based microelectronic devices.

Single crystals of boron-doped diamond (BDD) were synthesized by the temperature gradient method in high-pressure and high-temperature conditions in the Fe–Al–B–C system, and multisectoral diamond plates were extracted. Temperature-dependent (77–600 K) high-resolution Raman spectroscopic studies have been carried out to investigate the behavior of anharmonic phonon decay in the {001}, {113}, and {111} growth sectors of multisectoral diamond plates with different content of boron impurities (⩽80 ppm) and compare with the data for undoped IIa diamond. Micro-Fourier transform infrared spectroscopy was used to estimate the spatial distribution of uncompensated boron impurity [N a -N d ] in BDD plates by analyzing boron-related absorption peaks. The plates were shown to have non-uniform growth-sector-dependent content of uncompensated boron impurity in the range from 1.1 × 10 18 to 1.4 × 10 19 cm −3 . The effects of anharmonic decay (damping) of optical phonons in BDD are studied by modeling the temperature dependence of phonon frequency and linewidth of the diamond’s F 2g and boron-induced vibrational modes. The extrapolated zero-temperature optical phonon linewidth and frequency and the anharmonic nature of their linear relationship are determined as a function of the growth sector and boron doping. The predominant mechanisms and parameters of the anharmonic decay of optical phonons are determined, which is of fundamental importance for the thermal conductivity of semiconductor materials. The anharmonic phonon decay remained the predominant process at higher temperatures, irrespective of the doping level.

Morphological, structural, and nano-electrical features of the growth defects and sectoral boundaries revealed by selective etching in synthetic boron-doped single crystals of diamond (BDD) and multisectoral plates are characterized by a set of scanning probe microscopy (SPM) methods, confocal micro-Raman, and micro-FTIR spectroscopy. Diamond single crystals were grown under high pressure and high temperature conditions (HPHT) in the FeAlBC system. Morphology of dislocation etch pits and micro-defect related pits/protrusions compared both on the growth facets and multisectoral plates cut parallel to the {110} facet of BDD single crystals. Ex situ AFM observation of the etched surface revealed non-homogeneously distributed pits and protrusions over the growth facets correlated with irregular macroscopic growth defects. There is a center-to-periphery gradient of dislocation density in multisectoral plates. The protrusions are homogeneously distributed over plates; some often decorate dislocation pits. Micro-Raman mapping on dislocation pits (boron-rich regions) decorated by low-boron content regions revealed crystalline imperfections in three dimensions, with apparent compressive/tensile strain. The defects were mainly electrically neutral under surface potential mapping by Kelvin probe force microscopy, opposite to the inter-sectoral boundaries having pronounced surface potential steps. The scanning spreading resistance microscopy shows resistivity variations at etching-reviled surface defects and sectoral boundaries if the appropriate DC bias is applied to the SPM tip.

Boron-doped diamond (BDD) films grown by chemical vapor deposition (CVD) exhibit unique electrical and optical properties owing to the non-uniform uptake of boron dopants across grains. This study utilizes scanning probe microscopy and confocal micro- spectroscopy techniques to elucidate the influence of grain-dependent boron incorporation on the nano-electrical and local optical characteristics of polycrystalline BDD. The CVD- grown BDD film contained crystallites up to tens of microns, while the surface comprised 200…800 nm grains. Scanning spreading resistance microscopy (SSRM) revealed significant nanoscale resistance variations among individual grains, attributable to differential boron distributions. No distinct grain boundary features were discernible in SSRM data, likely due to the high boron doping of ~ 3·10 19 cm –3 . SSRM of the Au surface of a BDD/Ti/Pd/Au contact indicated a comparable granular morphology but three orders lower resistance. A network of more resistive grain boundaries was evident, modulated by underlying BDD grain clusters. Photoluminescence spectroscopy showed characteristic bands of nitrogen-vacancy centers and donor-acceptor pairs. Confocal Raman and photoluminescence mapping elucidated substantial spatial heterogeneity in micrometer- scale grains regarding crystal quality, boron and nitrogen concentrations, related to preferential incorporation. The observed peculiarities in BDD’s structural and nano- electrical characteristics stem from inherent growth inhomogeneities and grain-dependent boron uptake influenced by defects and strain fields modifying local chemical potentials. This multifaceted nanoscale examination provides critical insights into optimizing electrical and optical properties of BDD films by controlling synthesis conditions and minimizing defects for tailored performance in electronic, electrochemical, and quantum applications.

Thermobaric formation of carbon solvent alloys under high pressures of 4–6 GPa and at temperatures of 1200–1300°C is used to grow structurally perfect diamond single crystals in the region of thermodynamic stability. It is shown that the formation of samples with minimum values of porosity in the range from 2.49 to 4.50% ensures a stable distribution of elements over the growth volume even in the presence of large differences in the density of elements. For comparison, the results of experiments on the formation of solvent alloys by the methods of powder metallurgy and direct isostatic pressing with subsequent sintering and by the methods of hot pressing of powders are given. It is shown that the samples obtained by classical methods have relatively large final porosity values and cannot be used in the future as carbon solvent alloys during directed growth of diamond single crystals at high pressures and temperatures.

Owing to its extreme hardness, chemical stability and robustness, conductive diamond is an attractive material for scanning tunneling microscopy (STM). The selection of a suitable diamond and preparation of the STM tip is a challenge because electrically conductive diamonds can be grown using various methods and have anisotropic properties. A new method for the selection of conductive diamonds that is based on the registration and analysis of the tunneling I-V (TIV) characteristics of the tunnel junction between the diamond tip and graphite (0 0 0 1) surface at a constant tunneling gap is proposed. TIV should be monotonous while the tunneling currents vary from 0.1 to 6 nA with increasing bias voltages from 0.05 to 1 V. We found that HPHT diamonds grown in the Fe -Al-C-B growth system are more suitable for STM probs compared to grown in the Fe-Co-C-B system.

The possibility of using digital microphotogrammetry to analyze and simulate the habit and sectoral structure of diamond single crystals up to 20 mm in size grown under high pressures and temperatures (HPHT diamond) is considered. The prospects of such a method for developing cutting maps to cut single-sector samples and their subsequent use are shown.

We demonstrate the potential of using digital stereo micro-photogrammetry for the analysis and modeling of the habit and sectoral structure of real high-pressure high-temperature single-crystal diamonds. A prototype scanning system with a resolution of 5 μm has been implemented based on a digital single-lens reflex camera, making it possible to create highly accurate reproductions of crystal shapes with a minimum size of 4 mm. This method makes it possible to monitor the effect of actual conditions on the physical processes of crystal growth, which is a useful advance for the development of active device elements based on semiconductor diamonds.

Diamond single crystals in a Fe-Co alloy with addition of 5 and 10 wt.% Mg by temperature gradient method were grown and their morphology was studied. For crystals obtained in the Fe-Co alloy with 5 wt.% Mg, the faces of octahedron, cube, rhomb-dodecahedron and tetragon-trioctahedron {3 1 1} were observed. When the magnesium content in the solvent-alloy increase up to 10 wt.% under the same growth conditions the tetragon-trioctahedron {3 1 1} faces on diamond crystals were absent. The topography of diamond crystals faces grown in different systems indicates that octahedron and cube are active growth forms with their growth pyramids, and rhomb-dodecahedron and tetragon-trioctahedron {3 1 1} are forms of passive growth.

Boron-doped diamond single crystals of cubo-octahedral habit have been obtained by temperature gradient method at high pressures and high temperatures (HPHT) in Fe-Al-B-C system, and multisectoral plates of different orientations have been produced. Spatial distribution of uncompensated boron impurity and surface potential through the interfaces of different growth sectors of diamond plates have been studied by scanning Fourier transform infrared (FTIR) and Raman micro-spectroscopy, as well as scanning spreading resistance microscopy (SSRM) and Kelvin-probe force microscopy (KPFM). FTIR mapping showed strongly non-uniform growth-sector dependent distribution of uncompensated boron impurity gradually decreasing in a sequence {111}->{110}-> {113} -> {001} from ~7 . 10(18 )cm(-3) down to 2 . 10(17 )cm(-3). Micro-Raman mapping is used to reveal the submicron distribution of structural quality and boron content through the interfaces of different growth sectors. The inter-sectoral jumps of the surface potential in the axial and radial directions of the growth sectors were studied by KPFM, their theoretical estimates are obtained, and the features of the band structure of the inter-sector interfaces are revealed. A high level of structural perfection of inter-sectoral boundaries without electrically active defects is demonstrated.

This paper presents the results of a study of diamond single crystals of defect-impurity composition grown in a temperature gradient at high pressures and temperatures (HTHP-crystallization of diamond) in a Fe-Co-C solution with an addition of Mg depending on the amount of Mg, the content of nitrogen changes in various sectors of crystals growth, which causes a mixed type of crystals. The peculiarities of changes in the defect-impurity composition of the grown diamond single crystals were studied using IR spectroscopy and optical microscopy for concentration limits of 1.8-5.7 at. % of Mg content.

Some methodical approaches to the measurement of high quasi-hydrostatic pressures in the cells of six-punch presses with consideration for the effect of high temperatures up to 1400°C were described, and the combined load characteristic p = f(Q), where p is the pressure in a quasi-hydrostatic cell, and Q is the plunger system force, was constructed. The compression zone pressure is measured by determining the difference between the temperatures of polymorphic Fe(α→γ) and Co(α→β) transitions and the Cu and Ag melting temperatures and melting temperature by means of resistometry at a pressure of 4–7 GPa and a temperature of 500–700°С for Fe–Co sensors and 1150–1400°C for Cu–Ag sensors. To determine the high temperatures at the characteristic points of growth cells in six-punch presses, a method of manufacturing their thermocouple modules with the use of cesium chloride as an electroinsulating medium and Pt/PtRh10 and PtRh6/PtRh30 thermocouples was developed alongside with some basic requirements to their manufacturing to provide reliable electroinsulation for their thermocouple wires with continuous temperature control for growth cycles lasting for 200 h and longer. The effect produced by parasitic thermal electromotive forces (TEMFs) appearing due to the use of high pressures and additional contact through hard-alloy punches on thermocouple readings was estimated, and calibrating curves improving the measurement precision were plotted. The proposed approaches to estimating the pressures and temperatures in the growth cells of six-punch cubic high-pressure apparatuses can be especially useful when growing coarse diamond single crystals of more than 10 carats in weight.

Semiconducting boron-doped diamond single crystals of cubo-octahedral habit with prevalent development of octahedron {111} faces and insignificant area of cube {001}, rhombo-dodecahedron {110} and tetragon-trioctahedron {311} faces were obtained using solution-melt crystallization at high pressure 6.5 GPa and temperatures 1380…1420 °C. Using the Fe-Al solvent, which allows controlled incorporation of boron dopant between 2·10–4…10–2 at.% made it possible to vary the electro-physical properties of the crystals. Methods of micro-photogrammetry, atomic force microscopy, and micro-Raman spectroscopy were applied to reveal sectorial inhomogeneity of impurity composition and morphology of different crystal faces. The obtained crystals were shown to have high structural perfection and boron concentration ranging approximately from 1·1017 up to 7·1018 cm–3. An increase in boron concentration increases the area of {111} faces relatively to the total crystal area. Nanoscale morphological features like growth terraces, step-bunching, dendrite-like nanostructures, columnar substructures, negative growth pyramids on different crystal faces are shown to reflect peculiarities of carbon dissolution at high pressures and temperatures. The changes in the crystals’ habit and surface morphology are discussed in relation to inhomogeneous variation of thermodynamic conditions of crystal growth and dissolution at different boron concentrations.

Методом НРНТ-кристалізації вирощено структурно досконалі монокристали алмазу типу IIb, леговані бором з розвинутими секторами росту {113} і {110}. Односекторні пластини напівпровідникового алмазу одержані при прогнозованому розкрої кристалів шляхом механічної та лазерної обробки з використанням розробленого мікрофотограмметричного 3D моделювання секторальної структури. Методами раманівської та ІЧ-спектроскопії вивчено структурну досконалість, особливості дефектно-домішкового складу кристалів. Електронні властивості секторів росту та міжсекторальних меж охарактеризовано безконтактним методом силової кельвін-зонд-мікроскопії. Показано необхідність застосування визначених оптичних і електрофізичних діагностичних методів паспортизації напівпровідникового матеріалу р-типу і перспективність використання односекторних напівпровідникових пластин для розробки конструкцій діодів Шотткі.

The article raises the issues of zoning of rental forests taking into account climatic factors for the purpose of rational transport development of forests. The basis of the methodology for taking into account the influence of climatic factors in the organization and planning of forest transport processes through the average speed of timber trucks is proposed. The results of studies are given that allow taking into account the climatic parameters of the area where the enterprise is located.

The morphology of ultra-large polyhedra of diamond grown under high pressure and high temperature (5.6-5.8 GPa and 1400-1700 degrees C) in a growth system based on Fe-Co was studied. The grown diamond polyhedra are crystals of an octahedral habit with minor faces of a cube, rhombic dodecahedron, and trapezohedrons {311}, {5 1 1} and {7 1 1}. The morphological features of the grown crystals are the skeletal growth of faces of various simple forms and the so-called "binary growth" of single crystal. The characteristic of these growth phenomena is given and possible reasons for their manifestation are described.

The investigations performed at high pressures and high temperatures (HTHP crystallization) have permitted clarifying the mechanism of phase transformations and carbon transport in solvent metals for diamond growth and elaborating methods for growing large-size structurally perfect diamond single crystals of types Ib, IIa, and IIb. The findings have provided the basis for the process of production of diamonds for applications in electronics, laser technology, precision machining operations, well drilling tools. The use of a large-volume six-punch high pressure apparatus makes it possible to grow diamond single crystals with a higher efficiency. It is estimated that this apparatus is capable of producing annually at least 1 mln carats of structurally perfect crystals of required types for various applications.

The results of researches of physicochemical action on aggregate properties of nanodiamond are presented. The kinetics of aggregation of nanodiamond powder was studied as a function of time, temperature, and pH of the solution. The effect of the sp2–sp3 hybridization ratio of carbon in nanodiamond powders on their aggregation was studied. It is shown that the presence of non-diamond carbon in detonation synthesis nanodiamond powders leads to the increase of the mean diameters of particles, i.e., their agglomeration. The theoretical justification of the aggregation mechanism is proposed. It is shown that it is possible to control aggregative properties of nanodiamond powders by physicochemical influences, e.g., gas-phase thermal treatment to reduce the size of agglomerates and to create a well-developed reconstructed surface of diamond particles with a low content of functional groups on their surface.

Special features of the formation of the defect and impurity states of diamond single crystals grown in the Fe–Mg–Al–C growth system by the temperature gradient method at the pressure 7.2–8.2 GPa and temperature 1700–1900°C have been investigated. It has been shown that as the magnesium content of the growth system increases, the type of the grown crystals changes in the following sequence: IIa → IIb.

In the Mg-C system at p ≤ 8,2 GPa and Т» 1800-2000°C, structurally perfect IIa + IIb type diamond single crystals were obtained, and the peculiarities of their defect-impurity composition were considered. Grown diamonds were studied using IR spectroscopy. As a result of the research, it was found that in this system, it is possible to obtain diamonds with low nitrogen impurity concentration due to limiting its receipt to the crystallization front owing to forming the Mg3N2 nitride at high pressures and temperatures. It was revealed that in the grown diamond crystals, the boron impurity is present in various forms: B-N complexes (D-centers) with a characteristic absorption band at 1290 cm-1 and uncompensated (single) boron (characteristic absorption bands - 2460, 2810 and 2920 cm-1).