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Conformal multilayer micro-nanocrystalline diamond coatings were grown on substrates of a hard alloy with 9% Co with a high aspect number in microwave plasma from gas mixtures CH4/H2 and CH4/H2/N2. The substrates were of a cylindrical axial tool model with a size ratio: d = 12 mm to l = 75 mm. An original tool holder made of molybdenum, in the form of a sector of the excessive ring with the axis of the hole parallel to the central conductive platform, protects part of the substrate from heating due to the edge effect of plasma. The uniformity of heating of the growth part, which is located inside the excessive ring, is calculated using mathematical modeling and is provided by rotation at a speed of at least 12 rpm, which ensures the uniformity of the coating. The average grain size of the nanocrystalline film measured along the cylinder forming was 41 nm.

We investigate the propagation of laser-induced hypersound waves in polycrystalline diamond films by analyzing the spatial changes in the phase and amplitude of the probing laser beam reflected from the surface. We show that the velocity of bulk (longitudinal) acoustic waves is 14300 m/s in films with an average crystallite size of ≈ 0.2 μm and monotonically increases to 17200 m/s with increase in the crystallite size up to ≈ 2 μm. For surface waves, anomalous dispersion is observed, leading to a change in the phase velocity from ≈ 4800 to ≈ 6600 m/s, which is explained by the effective localization of the surface wave field in the diamond films. The values obtained can be used for the design of diamond films and membranes for applications in diamond photonics and acousto-electronics.

Nanodiamonds hosting temperature-sensing centers constitute a closed thermodynamic system. Such a system prevents direct contact of the temperature sensors with the environment making it an ideal environmental insensitive nanosized thermometer. A new design of a nanodiamond thermometer, based on a 500-nm luminescent nanodiamond embedded into the inner channel of a glass submicron pipette is reported. All-optical detection of temperature, based on spectral changes of the emission of “silicon-vacancy” centers with temperature, is used. We demonstrate the applicability of the thermometric tool to the study of temperature distribution near a local heater, placed in an aqueous medium. The calculated and experimental values of temperatures are shown to coincide within measurement error at gradients up to 20 °C/μm. Until now, temperature measurements on the submicron scale at such high gradients have not been performed. The new thermometric tool opens up unique opportunities to answer the urgent paradigm-shifting questions of cell physiology thermodynamics.

X-ray luminescent diamond composite films with embedded yttrium-aluminum nanoparticles were designed. Additionally, the stability limits of single-phase solid solutions in systems based on yttrium-aluminum and yttrium-scandium-aluminum garnets doped with cerium were determined. The most intense X-ray luminescence was achieved with the [Y2·98Ce0.02]{Al2}Al3O12 powder. The composition-optimized nanoparticles were embedded into a polycrystalline diamond matrix to form a diamond-YAG:Ce composite. For the obtained composite, an intense X-ray luminescence from the Ce3+ ions near 550 nm was demonstrated. The designed composites may be used as adjustable and durable scintillating materials for a wide range of applications.

The diamond composite materials with embedded yttrium-aluminum garnet doped with cerium (YAG:Ce) nanoparticles have been produced by microwave plasma-assisted chemical vapor deposition (CVD). Nanoparticles were synthesized by co-precipitation from an aqueous solution while CVD diamond served as the transparent matrix with high thermal conductivity, hardness, and resistivity to radiation damage. The composite films show high-intensity X-ray luminescence (XRL) with a broad band peaking around the wavelength of 550 nm (5d → 4f transition in Ce$^{3+}$ ion), and a narrow peak of silicon-vacancy (Si–V) centers at 738 nm. The characteristic decay time was measured at $τ_{Ce}$ < 50 ns for cerium emission and at $τ_{SiV}$∼1 ns for Si–V centers. Excitation spectra of both luminescence types measured near yttrium K-edge (17.1 keV) show a strong correlation, attributed to the excitation of Si–V luminescence by photoelectrons ejected from YAG:Ce nanoparticles. The discovered phenomenon suggests a new way to control X-ray visualization by luminescent diamond composites for fast X-ray detectors and screens.

A new type of substrates for the growth of nitride heterostructures is presented that consists of a 125-nm thick silicon layer and 290-μm thick polycrystalline diamond. The possibility of epitaxial growth of nitride heterostructures on silicon–polycrystalline diamond substrates with characteristics at the level of heterostructures on silicon substrates is shown. The test transistors demonstrated the following: saturation current density of more than 1 A/mm and breakdown voltage of more than 90 V. The achieved results open up opportunities for the emergence of a new class of silicon-polycrystalline diamond substrates and the creation of powerful gallium nitride transistors with previously unattainable characteristics.

A polycrystalline diamond film is grown on a 2 inch Si substrate using a microwave-plasma chemicalvapor-deposition technique. The high quality of the diamond films is confirmed by Raman spectra. A multiple-step procedure is used for local etching of the substrate to form the pattern of an array of 50 diamond membranes with the diameter in a range from 150 to 300 μm. The morphology of the membranes is examined using scanning electron microscopy. The membranes obtained can be used as the base material for the fabrication of pressure sensors, X-ray detectors and scintillators, and in quantum optics as optical resonators for single-color centers in diamond.

Thin-film diamond–rare earth fluoride nanocomposites have been produced by chemical vapor deposition to be used as a source of intensive photo- and X-ray luminescence. The composites with embedded ...

Solid-state photon emitters at room temperature appear to be promising candidates for a variety of nanophotonic applications. In this regard, coupling photon emitters with various optical cavities providing pronounced directivity, high photoexcitation and emission rates is extremely desirable. Here, we introduce the novel concept of deterministically coupling color centers in nanodiamonds (NDs) with gold nanopits. We show that in this case, emission of silicon-vacancy (SiV−) centers at the zero-phonon line can exceed that of a ND on a gold surface by a factor of 62. The obtained results reveal an effective pumping of the SiV-centers in NDs along with the active switching of the SiV-centers from the dark to the bright state by plasmon mode that opens the way to design controllable resonance systems with diamond-based photonic emitters.

The Diamond-NaGdF 4 : Eu and Diamond-YAG: Ce film composites were produced by chemical vapor deposition to be used as a source of intensive photo- and X-ray luminescence for radiation monitoring screens.

Nanocrystalline diamond (NCD) films were grown on the High Pressure High Temperature (HPHT) (110) single crystal (SC) diamond substrates by Microwave Plasma Enhanced Chemical Vapor Deposition (MPCVD) in methane/hydrogen/nitrogen plasma. The thickness of the films was varied between 2.2 and 22.5 μm. The cauliflower-like surface morphology was observed by means of Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The scaling behavior of NCD films growth was investigated. The relatively high value of the roughness exponent αs = 1.5–1.6 was found indicating anomalous scaling. Therefore, shadowing and diffusional instabilities can affect the film growth. The tribological properties of the NCD films deposited on the SC(110) diamond were compared with the NCD films prepared on the Si(100) substrates. Both types of specimens were tested under similar Hertzian contact pressure. The lower wear volume losses were observed on the NCD/SC(110) specimens. Therefore, the influence of substrate and substrate/film interface properties on the tribological behavior of the NCD films grown on Si(100) can be expected to cause NCD films deflection.

Germanium-Vacancy (Ge-V) color center in diamond possesses a narrow band photoluminescence (PL) emission in the orange spectral range interesting as a single-photon source for quantum optical technologies and thermometry, therefore, development of methods for the controllable doping of diamond with Ge is of high importance for such applications. Here, we report on the synthesis of polycrystalline and epitaxial single crystal Ge-doped films using microwave plasma chemical vapor deposition (CVD) technique by addition of the germane GeH4 gas into the H2-CH4 plasma. It is demonstrated, that GeH4 addition affects the CVD growth of microcrystalline diamond, reducing the film growth rate and increasing the average diamond grain size. The films show bright photoluminescence of Ge-V centers at ≈602 nm under the optimized GeH4 concentration, with a zero-phonon line width of 1.6 nm (FWHM) for Ge-V ensemble at low temperatures (5 K). The developed in-situ doping from the germane gas opens a way for a better control of the Ge-V color center formation in diamond for photonic applications.

Raman and fluorescence spectroscopic techniques were used to study doped nanodiamonds synthesized at high pressure and high temperature (HPHT technique) and by chemical vapor deposition from the gas phase (CVD technique). For the CVD diamonds, a hundred-fold increase in fluorescence intensity of the silicon-vacancy centers normalized to the volume of the probe material was observed with an increase in synthesized diamond particle diameter from 150 to 300 nm. Graphitization temperature upon heating in the air significantly lower than for detonation nanodiamonds was found for the boron-doped HPHT nanodiamonds.

The kinetic characteristics and temperature quenching of the luminescence of optical centers of silicon vacancies (SiVs) in diamond films grown in microwave plasma on substrates of aluminum nitride and synthetic diamond are investigated via laser excitation at a wavelength of 640 nm.

Micro- and nanocrystalline uniform diamond coatings with barrier tungsten layers for improved adhesion were deposited in a microwave plasma from methane-hydrogen mixtures on cemented carbide WC–6% Co substrates with high aspect ratios. Dynamic study of cutting forces and sliding friction has shown a significant improvement in the tribological properties of diamond-coated tools in cutting highly abrasive materials, such as A390 silumin and carbon-carbon composites. Confocal Raman spectrometry has been used to examine the features of wear mechanism in nano- and microcrystalline diamond coatings deposited in a microwave plasma.

Single- and multilayer coatings of micro- and nanocrystalline diamond were deposited on tungsten carbide substrates (WC + 6 wt.% Co alloy) in a microwave plasma of methane/hydrogen and methane/hydrogen/nitrogen mixtures. Barrier tungsten layers were used to improve adhesion of the diamond coatings to the substrates. Raman spectroscopy was used to study the properties of the nano- and microcrystalline diamond coatings depending on the deposition parameters. Data on structural transformations of the coatings under different tribological contact conditions were obtained, and secondary nucleation processes were investigated on different diamond faces during the deposition from the gas phase.

Polycrystalline diamond coatings have been grown on cemented carbide WC-6% Co substrates with different aspect ratios by microwave plasma CVD in CH4/H2 gas mixtures. Special plateholder with holes for group growth has been used to protect the edges of the substrates from non-uniform heating due to the plasma edge effect. The difference in heights Δh of the substrates and plateholder, and its influence on the diamond film mean grain size, growth rate, phase composition and stress was investigated. Diamond growth rate of 0.3–1 μm/h and compressive stress of 2.2–2.5 GPa, respectively were determined in the optimal Δh region. The substrate temperature range of 740–760 °C, within which uniform diamond films are produced with good adhesion, is determined. The diamond-coated samples produced at optimized process conditions exhibited a reduction of cutting force and wear resistance by a factor of two, and increase of cutting path length up to 8150 m or by 4.3 times upon turning А390 Al-Si alloy as compared to performance of uncoated tools.

The optical properties of color centers in nanodiamonds are widely used in various branches of photonics and interdisciplinary studies. Here, we report on an experimental study of the fundamental eigenmodes of subwavelength diamond nanoparticles. The eigenmodes reveal themselves as scattering resonances, which were measured by single-particle dark-field spectroscopy and calculated both numerically and analytically. The resonances experience a red-shift with increasing particle size, and in the case of an anisotropic particle, they change depending on the polarization of the input light. As an example of an application, the Purcell enhancement of the dipole emission from such nanodiamonds is numerically demonstrated. This study demonstrates a simple way to improve the efficiency of diamond-based sensors and single-photon sources by choosing nanoparticles of optimal size and shape.

New methods have been developed for obtaining three preceramic polycarbyne-family polymers. Poly(hydridocarbyne) (PHC) and poly(phenylcarbyne) (PPC) have been synthesized via a mechanically activated reaction between magnesium metal and CRX 3 (R = H, Ph; X = Br, Cl). Poly(naphthalene- co -hydridocarbyne) (PNHC) have been obtained by reacting CHBr 3 with sodium naphthalide. The efficiencies of PHC, PPC, and PNHC as sources of diamond nuclei in the microwave plasma chemical vapor deposition of diamond films on silicon substrates have been compared. The highest efficiency has been demonstrated by PHC with a high molecular weight, for which the nucleation density has been estimated at ≥ 10 9 nuclei per square centimeter of the substrate surface.

Pressure sensors based on diamond membranes were designed and tested for gas pressure measurement up to 6.8 MPa. The diamond film (2” diameter, 6 μm thickness)—grown by microwave plasma chemical vapor deposition on a silicon substrate—was a starting material to produce an array of membranes with different diameters in the 130–400 μm range, in order to optimize the sensor performance. Each 5 mm × 5 mm sensing element was obtained by subsequent silicon slicing. The fixed film thickness, full-scale pressure range, and sensor sensitivity were established by a proper design of the diameter of diamond membrane which represents the sensing element for differential pressure measurement. The pressure-induced deflection of the membrane was optically measured using a Fabry-Pérot interferometer formed by a single mode optical fiber front surface and the deflecting diamond film surface. The optical response of the system was numerically simulated using geometry and the elastic properties of the diamond diaphragm, and was compared with the experiments. Depending on the diamond membrane’s diameter, the fabricated sensors displayed a good modulation depth of response over different full-scale ranges, from 3 to 300 bar. In view of the excellent mechanical, thermal, and chemical properties of diamond, such pressure sensors could be useful for performance in a harsh environment.

We report the manufacturing of a novel diamond – rare-earth (RE) composite material with EuF 3 nanoparticles (NP) embedded in the synthesized microcrystalline diamond films that show strong photoluminescence in the orange part of the visible spectrum. Synthesis of the aforementioned composite includes placement of EuF 3 NP on the diamond substrate and subsequent coating of them with an additional polycrystalline diamond layer grown by microwave plasma chemical vapor deposition (CVD). The produced composite films exhibit high intensity localized photoluminescence (PL) at 612 nm with the decay time of 0.34 ms, which is generated by the EuF 3 particles buried within a very stable transparent diamond matrix. The proposed synthetic approach is quite versatile, as it allows preparation of the luminescent diamond - RE particles nanocomposites of different sizes and natures which perform well over a broad range of the visible spectrum.

Nanocrystalline (NC) diamond films are grown by chemical vapor deposition on various single crystal diamond faces. Under conditions of NC diamond growth, the growing filmmorphology is reduced to two planes: {100} and {111}. The {100} planes are smooth and homoepitaxial layerby-layer growth occurs on them, whereas the NC film formed by twin crystalliteswith sizes of several tens and hundreds nanometers grows on {111} planes. Nitrogen impurity sharply increases the diamond growth rate.

Silicon-doped microcrystalline diamond films of 1 μm thickness were grown by chemical vapor deposition in microwave plasma from mixtures of methane–hydrogen–silane on substrates of aluminum nitride, tungsten, and silicon. The diamond films were found to contain optically active silicon vacancy (SiV) centers giving rise to the 737-nm band in the photoluminescence spectra. The spectral features of a newly discovered narrow band of comparable intensity at 720–722 nm were studied. It is shown that the band at 720–722 nm occurs in the photoluminescence spectra only in the presence of silica in the diamond, regardless of the substrate material. The temperature dynamics of the photoluminescence spectra in the range of 5–294 K were investigated. The possible nature and mechanisms of formation of the color centers responsible for the 720–722 nm band are discussed.

Microwave (MW) plasma in silane-hydrogen and silane-hydrogen-methane mixtures is used effectively for chemical vapor deposition of Si, SiC, diamond, and SiC-diamond composite films; however, the properties of such plasma at pressures of the order of 100 Torr remain largely unexplored. Here we characterize the MW plasma (2.45 GHz) in SiH4 + H2 and SiH4 + СH4 + H2 mixtures (72 Torr) with silane content ranging from 0% to 5% in the process gas using high-resolution optical emission (OE) spectroscopy. Besides the OE lines of C2 dimer, Balmer series of excited atomic hydrogen (Hα, Hβ, Hγ, Hδ, and He), and CH radical, we observed atomic Si lines at 263, 288, and 391 nm and a relatively weak SiH emission. Gas temperature Tg of ≈3160 K is assessed from the rotational structure of the C2 dimer (Δν = 0, λ = 516.5 nm) emission band, and the absorbed microwave power density (MWPD) in the plasma fluctuates in the narrow range between 36 and 43 W/cm3 with a slight tendency to decrease with silane addition. The MWPD, intensity ratio Hα/Hβ of hydrogen Balmer series lines (related to excitation temperature Texc), and Si lines’ intensities in OE spectra as functions of SiH4 concentration in H2 and H2 + CH4 mixtures all show an extremum or a kink in slope near a special point at ≈0.5% SiH4. Finally, we produced a silicon carbide film of cubic polytype 3C-SiC on a (111) oriented Si substrate, which was characterized with Raman spectroscopy and x-ray diffraction, and its monocrystalline structure was confirmed.

Microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films were synthesized on Si substrates by a microwave plasma chemical vapor deposition in methane-hydrogen gas mixtures with a wide range of methane concentrations of 0.5–40%. The samples were investigated with scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. We observed an unusual transition of the produced material structure from MCD to NCD and again to MCD with the increase in CH4 content in the gas. The deposition rate, grain size, and the roughness of the films exhibited extrema in the middle of the methane concentration range ([CH4] = 20%). Further increase of CH4 percentage leads to improvement of the diamond film quality, as confirmed by Raman spectra and SEM images while keeping a high deposition rate. These results may be used for the growth of the wide range of PCD films to be used as multipurpose protective layers, hard coatings for the cutting tools, and the diamond base for composite MCD/NCD structures.

In this work, the substrate holders of three principal geometries (flat, pocket, and pedestal) were designed based on E-field simulations. They were fabricated and then tested in microwave plasma-assisted chemical vapor deposition process with the purpose of the homogeneous growth of 100-&mu, m-thick, low-stress polycrystalline diamond film over 2-inch Si substrates with a thickness of 0.35 mm. The effectiveness of each holder design was estimated by the criteria of the PCD film quality, its homogeneity, stress, and the curvature of the resulting &ldquo, diamond-on-Si&rdquo, plates. The structure and phase composition of the synthesized samples were studied with scanning electron microscopy and Raman spectroscopy, the curvature was measured using white light interferometry, and the thermal conductivity was measured using the laser flash technique. The proposed pedestal design of the substrate holder could reduce the stress of the thick PCD film down to 1.1&ndash, 1.4 GPa, which resulted in an extremely low value of displacement for the resulting &ldquo, plate of &Delta, h = 50 &mu, m. The obtained results may be used for the improvement of already existing, and the design of the novel-type, MPCVD reactors aimed at the growth of large-area thick homogeneous PCD layers and plates for electronic applications.

Thin polycrystalline diamond films chemically vapor deposited on thinned silicon substrates were used as membranes for pressure sensor fabrication by means of selective chemical etching of silicon. The sensing element is based on a simple low-finesse Fabry&ndash, P&eacute, rot (FP) interferometer. The FP cavity is defined by the end-face of a single mode fiber and the diamond diaphragm surface. Hence, pressure is evaluated by measuring the cavity length by an optoelectronic system coupled to the single mode fiber. Exploiting the excellent properties of Chemical Vapor Deposition (CVD) diamond, in terms of high hardness, low thermal expansion, and ultra-high thermal conductivity, the realized sensors have been characterized up to 16.5 MPa at room temperature. Preliminary characterizations demonstrate the feasibility of such diamond-on-Si membrane structure for pressure transduction. The proposed sensing system represents a valid alternative to conventional solutions, overcoming the drawback related to electromagnetic interference on the acquired weak signals generated by standard piezoelectric sensors.

The article presents the results of using optical methods of non-destructive testing during synthesis of diamond coatings (DC) from microwave plasma (the MPCVD method) on hard alloy tools for processing highly abrasive composite materials. Using the methods of optical emission spectroscopy and measuring the operating temperature of the substrates applying an infrared pyrometer, the average discharge power density in a microwave plasma reactor during the group growth of micro- and nanocrystalline DC has been found for the first time. Heating control of cobalt-bonded hard alloy substrates in microwave plasma reactor is practically achieved by feedback with the indication of an infrared pyrometer. Using the Raman spectroscopy method, we confirm the result of applying a high-quality DC on a tool with thin cutting edges.The article presents the results of using optical methods of non-destructive testing during synthesis of diamond coatings (DC) from microwave plasma (the MPCVD method) on hard alloy tools for processing highly abrasive composite materials. Using the methods of optical emission spectroscopy and measuring the operating temperature of the substrates applying an infrared pyrometer, the average discharge power density in a microwave plasma reactor during the group growth of micro- and nanocrystalline DC has been found for the first time. Heating control of cobalt-bonded hard alloy substrates in microwave plasma reactor is practically achieved by feedback with the indication of an infrared pyrometer. Using the Raman spectroscopy method, we confirm the result of applying a high-quality DC on a tool with thin cutting edges.

A two-layered diamond plate is proposed as a transparent X-ray window visualizer. The plate consists of a thick substrate of a synthetic single-crystal high-pressure high-temperature (HPHT) diamond on which a thin $${\sim }10\, {\mu }m$$ optically active layer of chemical vapor deposition (CVD) diamond doped with silicon and nitrogen, and is epitaxially grown. The photoluminescent properties of the diamond sandwich plate were studied under the influence of X-ray radiation before and after treatment of the plate with high-energy electrons and its thermal annealing. It was established that broadband luminescence with a maximum near 500 nm, associated with defects of the HPHT diamond substrate, dominates before electron treatment. The electron irradiation and subsequent annealing of the plate completely suppressed the broadband luminescence and significantly (by more than two orders of magnitude) increased emission intensity of nitrogen-vacancy centers (NV) in the CVD diamond layer. As a result, the luminescence of neutrally charged NV centers with a zero-phonon line at 575 nm became dominant. No luminescence of the silicon-vacancy (SiV) centers in the CVD diamond film was detected. The first results demonstrating the two-layered diamond plate as an X-ray visualizer are presented.

We produced luminescent diamond films with embedded europium-contained fluorides which were synthesized by different precipitation techniques. Luminescence spectra showed a narrow orange line at 612 nm. This approach has a perspective for the preparation of luminescent diamond with wanted luminescence lines.

Nanocrystalline diamond (NCD) films were produced by microwave plasma enhanced chemical vapor deposition (MPCVD) in methane/hydrogen/air plasma. The thickness of the films was varied from 0.15 to 22 μm. X-ray diffraction (XRD), Raman spectroscopy and atomic force microscopy (AFM) were used to investigate the structure and surface morphology of the films. During a short initial period of the deposition, i.e. from 2.5 min to 60 min, the growth dynamics involve relatively strong non-local effects, followed by a growth stage, which is characterized by a contribution of non-local and non-linear effects to the growth dynamics. The later regime of growth with roughness exponent α ~ 0.35–0.4 and growth exponent β ~ 0.25 can be related with the Kardar–Parisi–Zhang (KPZ) scaling regime of growth. The morphological peculiarities observed on the NCD film surface after already 2.5 min of deposition influence the morphology of the films for prolonged deposition time. Therefore, control over the size and distribution of these peculiarities by systematic variation of the deposition parameters allows to optimize the surface morphology for specific applications. The mountain-like patterns observed on the NCD films surface can be related to conformal KPZ growth regime, in contrast to the cusp-like patterns caused by non-local effects and noise.

Luminescence properties of nitrogen-vacancy (NV) and silicon-vacancy (SiV) centers were investigated for the series of O-terminated composite nanodiamonds consisting of a high-pressure–high-temperature (HPHT) diamond core and a chemical-vapor-deposition (CVD) diamond outer layer of different thickness. It was found that emission of NV and SiV centers cease to “feel” the diamond surface at a distance of 12 and 4 nm, respectively, from it. This finding determines minimum sizes of O-terminated nanodiamonds in which stable single photon emitters could be formed based on NV and SiV centers. Suggested composite diamond nanostructure are optimal for design of two-color luminescent markers. The studied diamond nanoparticles present composite structure of “core-outer layer” type. The core is 20 nm HPHT diamond containing NV centers, whereas outer diamond layer containing SiV centers is formed by CVD synthesis.

Nanocrystalline diamond (NCD) and microcrystalline diamond (MCD) films with bright photoluminescence (PL) of silicon-vacancy (SiV) color centers at 738 nm have been grown using a microwave plasma CVD technique. The films were doped with Si via adding silane to CH4–H2 reaction gas mixture in the course of the deposition process. The dependence of SiV PL intensity on silane concentration in gas shows a maximum at SiH4/CH4 ratios of 0.2% and 0.6% for NCD and MCD films, respectively, the maximum intensity for MCD being an order of magnitude stronger compared with that for NCD. The PL quenching at higher CH4 addition occurs, however, no significant degradation of the film structure, such as Si-induced amorphous carbon formation, was observed within the SiH4 concentration range studied (0%–0.9%). The higher PL efficiency of the MCD films is related to their less defective structure, as deduced from Raman spectroscopy analysis.

In germanium-doped thin polycrystalline diamond films grown in microwave plasma on Ge substrates, strong photoluminescence in the orange spectral region with a zero-phonon line (ZPL) at a wavelength of 602 nm is detected. The ZPL width is 4–5 nm at room temperature and 1.2 nm at T = 5K. It is assumed that the new optically active defect is a germanium–vacancy (Ge–V) complex similar to the known Si–V color center in diamond.

Homoepitaxial single crystal diamond layers with bright photoluminescence (PL) of silicon-vacancy (SiV) color centers at 738 nm wavelength have been grown on (100) diamond substrates by a microwave plasma CVD using a controlled Si doping via adding silane to CH4H2 reaction gas mixture in the course of the deposition process. In the range of the silane concentrations SiH4/CH4 explored, from 0 to 2.4%, the SiV PL intensity shows a nonmonotonic behavior with silane addition, with a maximum at 0.6%SiH4/CH4, and a rapid PL quenching at higher Si doping. The maximum SiV concentration of ≈450 ppb in the samples has been determined from optical absorption spectra. It is found that the SiV PL intensity can strongly, an order of magnitude, increase within non-epitaxial inclusions in single crystal diamond film.

Micro/Nanocrystalline multilayer diamond coatings (DC) were produced using a microwave plasma-assisted CVD process from CH 4 /H 2 (microcrystalline) and CH 4 /H 2 /N 2 (nanocrystalline) gas mixtures and deposited on common tungsten carbide tools. High resolution surface electron microscopy, Raman spectroscopy, friction, wear and scratching resistance tests were performed to study properties of the four series of DC. It was shown that such multilayer DC not only display good adhesion and wear resistant properties, but also have high surface smoothness and extremely low friction coefficient.

The processes of the synthesis of silicon-doped microcrystalline diamond films on AlN and Si substrates in microwave plasma in “methane-hydrogen-silane” mixtures were studied. It is shown that the dependence of the photoluminescence (PL) line intensity of silicon-vacancy centers in diamond (λ = 738 nm) on the silane concentration in a gas mixture passes through a maximum at SiH4/CH4 concentrations of 0.1% for Si substrates and 0.6% SiH4/CH4 for aluminum nitride substrates. It was found that such nonmonotonic variation of the PL intensity with increasing silane concentration occurs despite the unchanged growth rate of the diamond film, its structure, and phase composition in the studied silane concentration SiH4/CH4 range of 0–0.9%.

A coating technology for application of hardening of diamond coatings on carbide tools for treatment of mineral fiberglass based on quartz texture with chromate-phosphate cohesive (FQTCC) is proposed. The purpose of this development is to increase the edge strength of the tool. The use of the technology described above allowed, in comparison with the cutter without diamond coating, to increase the productivity of processing by 11.5 times, by cutting speed by 2.3 times, and by the minute supply by 5.0 times. The approach is based on changing the configuration of the microwave field when applying a diamond coating on hard alloy substrates in the microwave plasma of the ARDIS-100 reactor by using specially designed plateholders. This method allows for the group coating on several substrates in a single process. A simplified mathematical model for calculating the temperature of the top of the cutter during the growth of a CVD diamond film, taking into account heat transfer through thermal conductivity and radiation, has been constructed. Temperature distribution on the surface of a tungsten carbide cutter in the temperature range optimal for diamond growth was constructed. The difference between the average (experimental) and maximum (calculated) temperature in such a cutter was from 80 to 138°C.

The co-deposition of diamond and silicon carbide (SiC) was realized in a microwave plasma using H2-CH4-SiH4 mixtures at enhanced microwave power density of up to 150 W/cm3, and SiC/diamond composite films on (100) Si substrates were produced. The growth parameters were selected to ensure almost equal deposition rates of ~0.3 μm/h for both phases. Composite films were formed either directly on Si surface, or on a buffer (nucleation) layer of SiC or diamond, preliminary deposited on the Si substrate. The film structure has been characterized by SEM, XRD, Raman and PL spectroscopy. It was confirmed that the silicon carbide phase in the composite is the cubic polytype β-SiC (3C-SiC) with the presence of only a small fraction of the hexagonal polytype, while the diamond is in well-faceted microcrystalline form. Diamond grains are Si-doped as was evidenced by the strong photoluminescence of silicon-vacancy color centers. Also, minor inclusions of amorphous sp2 carbon and of trans-polyacetylene (t-PA) were detected in the β-SiC phase. The overall crystalline quality of the composite is high, as evidenced by narrow Raman peaks both for diamond and β-SiC. Our results show, that with an appropriate choice of growth parameters, particularly SiH4/CH4 ratio, high-quality films of Si-doped diamond, silicon carbide, SiC-diamond composite, and combinations of these structures can be synthesized in a single process. Prime novelty statement The co-deposition of diamond and SiC was realized by microwave plasma CVD using H2-CH4-SiH4 mixtures at enhanced microwave power density; β-SiC/diamond composite films were produced with high crystalline quality on (100) Si substrates.

Ability to precisely control the Si-related color center abundance in diamond is important for the use of silicon-vacancy (SiV) defects with bright photoluminescence (PL) in quantum information technologies and optical biomarkers. Here, we evaluated the efficiency of Si incorporation in (100) plane of homoepitaxial diamond layers upon in situ doping by adding silane SiH4 in the course of diamond chemical vapor deposition in microwave plasma using CH4–H2 mixtures. Both the Si concentration in the doped samples, as determined by secondary ion mass spectrometry, and PL intensity of SiV centers at 738 nm wavelength, measured at excitation wavelength of 473 nm, demonstrate a linear increase with silane content in feed gas in the range. The incorporation efficiency f, defined as the ratio of Si concentration in diamond to that in gas, f = [Si/C]dia/[Si/C]gas is found to be (1.1 ± 0.5) × 10−3 for the silane concentrations explored, [SiH4/CH4]

It has been shown that layers of a certain type of polymers applied to silicon substrates at the thermal destruction form (in parallel with sp2 coordinated carbon) diamond nanoparticles, which act as nucleation centers of crystallites in the subsequent chemical vapor deposition of diamond. Microcrystalline diamond films have been synthesized from methane-hydrogen mixtures by microwave plasma using poly(naphthylhydrocarbyn) and poly(hydrocarbyn) preceramic polymers.