Search

This study focused on the investigation of the edge effect of diamond films deposited by microwave plasma chemical vapor deposition. Substrate bulge height is a factor that affects the edge effect, and it was used to simulate plasma and guide the diamond-film deposition experiments. Finite-element software COMSOL Multiphysics was used to construct a multiphysics (electromagnetic, plasma, and fluid heat transfer fields) coupling model based on electron collision reaction. Raman spectroscopy and scanning electron microscopy were performed to characterize the experimental growth and validate the model. The simulation results reflected the experimental trends observed. Plasma discharge at the edge of the substrate accelerated due to the increase in Δh (Δh = 0–3 mm), and the values of electron density (ne), molar concentration of H (CH), and molar concentration of CH 3 (C CH 3 ) doubled at the edge (for the special concave sample with Δh = −1 mm, the active chemical groups exhibited a decreased molar concentration at the edge of the substrate). At Δh = 0–3 mm, a high diamond growth rate and a large diamond grain size were observed at the edge of the substrate, and their values increased with Δh. The uniformity of film thickness decreased with Δh. The Raman spectra of all samples revealed the first-order characteristic peak of diamond near 1332 cm−1. When Δh = −1 mm, tensile stress occurred in all regions of the film. When Δh = 1–3 mm, all areas in the film exhibited compressive stress. [ABSTRACT FROM AUTHOR]

Diamond films were prepared on silicon nitride and zirconia ceramic substrates using hot filament chemical vapor deposition (HFCVD). The surface morphology, friction, and wear properties of the diamond films prepared with different methane concentrations (2%, 4%, and 6%) were compared using scanning electron microscopy, Raman spectroscopy, X-ray diffraction, and friction and wear testing machines. The results showed that, with an increase in the methane concentration, the diamond particles gradually changed from micro- to nanodiamonds, and the grain size first increased and then decreased. The diamond films on silicon nitride substrates were of excellent quality, with good wear resistance, strong adhesion, and wear rates of 2.857 × 10−8 mm−3•m−1•N−1, 5.151 × 10−8 mm−3•m−1•N−1, and 1.334 × 10−7 mm−3•m−1•N−1, respectively. The diamond films on zirconia substrates had more impurities on the surface, higher internal stress, poorer wear resistance, and weaker adhesion, with wear rates of 3.789 × 10−8 mm−3•m−1•N−1, 5.899 × 10−8 mm−3•m−1•N−1, and 2.074 × 10−7 mm−3•m−1•N−1, respectively. Hence, the deposition of diamond films on ceramic substrates significantly reduced the friction coefficient, and the performance of diamond films on silicon nitride substrates was excellent. [ABSTRACT FROM AUTHOR]

The plasma emission spectrum and polycrystalline diamond growth within 4 inches was studied by using a microwave plasma chemical vapor deposition (MPCVD) equipment with a microwave frequency of 2.45 GHz and a power of 10 kW, a 4-inch free-standing diamond thick film was prepared, and the growth uniformity, crystal quality at different positions, room temperature thermal conductivity, ultraviolet-visible-near infrared spectral transmittance and dielectric properties of diamond film were characterized. The results show that the freestanding diamond films are prepared with good uniformity and crystallinity at 10 kW power with high concentration and chemical activity of carbon and hydrogen active particles within the plasma diameter of about 100 mm. The thermal conductivity at room temperature reaches more than 1894 W/m·K, the infrared transmittance reaches more than 70%, the dielectric constant is 5.5, and the dielectric loss is 5.9 × 10−5. This study provides a theoretical possibility for the preparation of large-area high-quality diamond films in low-power MPCVD equipment.

Experimental results showed that for the diamond film prepared by hot filament chemical vapor deposition (HFCVD) using Ta filament, TaC existed between diamond and the silicon substrate, and diamond grew directly on TaC, while the inherent mechanism was not clear. Here, a special coherent interface Diamond(111)//TaC(111) is observed using high resolution transmission electron microscopy, and then we explore the effects of the TaC with different lattice planes on the diamond formation by first-principle calculations. The results show that C tends to adsorb on the TaC(111) C-terminated surface. The strong covalent bond between C from diamond and Ta from TaC is formed in the Diamond(111)//TaC(111) interface, while only C–C covalent bonds are formed at the Graphite(002)/TaC(111). This makes diamond thermodynamically more stable than graphite on the TaC surfaces. Our investigations provide critical information to understand the complex diamond formation mechanism, especially with the presence of TaC.

In order to deposit diamond films on zirconia ceramic substrates, a three-dimensional finite element simulation of the substrate temperature field is proposed to optimize the deposition process parameters. First, the validity of the simulation results is verified by experiments in the actual deposition system. Second, the influence of parameters such as the height of the hot filament (h ), the distance of the hot filament (d ), the number of hot filaments (N ), and the presence or absence of cemented carbide ingots on the uniformity of the temperature field of the substrate is analyzed through temperature field simulation. Third, according to the optimal parameters obtained from the simulation results, the diamond film was deposited on the zirconia ceramic substrate by experiment. Finally, the properties of diamond films deposited on zirconia ceramic substrates with optimized parameters are characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The simulation results have indicated that the optimal parameters obtained are h = 4 mm , d = 7 mm , and N = 7 , and the protective cemented carbide ingot is acceptable due to its negligible temperature impact. The diamond film prepared according to the optimized parameters is a typical micro-diamond film, with relatively dense growth, grain size of about 0.6 ~ 1 μ m , deposition rate of about 0.625 μ m / h , residual stress of about − 6.61 GPa , and FWHM of 18 cm −1. However, impurities are present on the surface of the diamond film prepared without optimization parameters, and the graphitization is more serious. The residual stress is about − 9.07 GPa , and the FWHM is 23 cm −1. The quality of diamond films is significantly improved through parameter optimization. [ABSTRACT FROM AUTHOR]

A novel transient liquid phase bonding (TLP) method for obtaining high-temperature resistant diamond/Cu joint was designed. The joint was achieved through the isothermal solidification of Au–Si interlayer assisted by the diamond active modified layer and NiTi particles. The interfacial reaction mechanisms in the TLP process were systematically investigated in this study. The results shown that Ti 5 Si 3 C, CuTiSi and NiTiSi precipitated from the seam. Due to the precipitation of Si and the interdiffusion of Au–Cu, a ductile Au–Cu solid solution ((Au, Cu)ss) matrix formed. The shear strength of the diamond/Cu joint was notably affected by the holding time. The maximum room-temperature shear strength of 108 MPa was achieved when the joints were held at 600 °C for 60 min, and the high-temperature strength was still up to 22 MPa at 600 °C. The high strength of the joints was achieved because of (i) the elimination of the Cu(Au)–Si brittle phases, (ii) the NiTiSi whiskers pulling-out mechanism, and (iii) the moderate distribution of compounds at the diamond/seam interface. [ABSTRACT FROM AUTHOR]

In order to solve the problem that it is difficult to grow diamond films with high binding force on the surface of high cobalt cemented carbide, the Cr/CrSiN film was used as the transition layer, and the nanocrystalline diamond films (NCD), the submicrocrystalline diamond films (SMCD) and the microcrystalline diamond films (MCD) were deposited on the cemented carbide by hot filament chemical vapor deposition method, and their binding forces were studied. The results show that the Cr/CrSiN transition layer can be used to deposit diamond films with excellent bonding strength on the surface of high cobalt cemented carbide. NCD has the best binding force, followed by SMCD, and MCD has the worst binding force. When the grain size of the diamond film increases, the bonding forces of the diamond film weaken due to the poor toughness of the diamond films and severe carbonization of the transition layer. When the crystal size of the diamond film increases, the binding force of the diamond film becomes weak due to the poor toughness of the diamond film and serious carbonization of the transition layer.

The diamond film is prone to oxidation in environment above 600 °C, making it difficult to maintain good wear resistance at high-temperatures. The high temperature oxidation resistance of diamond films can be improved through multiple doping. However, its wear resistance and anti-friction performance during high-temperature processing remain to be studied. In this study, single-doped, co-doped, and multi-doped diamond films with B, N, and Si doping combinations were fabricated on the surface of cemented carbide substrates. Performance characterization and high-temperature friction experiments were carried out on these films. The results show that B-doping can enhance wear resistance at high temperatures, N-doping can improve hardness, and Si-doping can reduce the coefficient of friction (CoF) of the diamond film. The multi-doped diamond film exhibits a comprehensive improvement effect due to the combination of different doping elements. During the high-temperature friction process, its CoF is significantly lower than that of undoped diamond film, resulting in a relatively high surface finish of the silicon nitride ball friction against it. Additionally, its excellent high-temperature wear resistance leads to minimal grain wear on the film surface and a low degree of transition from diamond to graphite phase on the surface. This study provides valuable insights for the application of multiple doped diamond films in high-temperature processing. [ABSTRACT FROM AUTHOR]

In order to solve the problem that it is difficult to grow diamond films with high binding force on the surface of high cobalt cemented carbide, the Cr/CrSiN film was used as the transition layer, and the nanocrystalline diamond films (NCD), the submicrocrystalline diamond films (SMCD) and the microcrystalline diamond films (MCD) were deposited on the cemented carbide by hot filament chemical vapor deposition method, and their binding forces were studied. The results show that the Cr/CrSiN transition layer can be used to deposit diamond films with excellent bonding strength on the surface of high cobalt cemented carbide. NCD has the best binding force, followed by SMCD, and MCD has the worst binding force. When the grain size of the diamond film increases, the bonding forces of the diamond film weaken due to the poor toughness of the diamond films and severe carbonization of the transition layer. When the crystal size of the diamond film increases, the binding force of the diamond film becomes weak due to the poor toughness of the diamond film and serious carbonization of the transition layer. [ABSTRACT FROM AUTHOR]

Diamond has an extremely high thermal conductivity, making it to have a great potential as a heat dissipation material. Based on the hot filament chemical vapor deposition (HFCVD) technique, diamond thick films were deposited on silicon carbide substrates by using the multi-step method in this paper. The scanning electron microscopy (SEM) and Raman spectroscopy were adopted for characterizing the samples. The influences of filament power, carbon concentration, and reactive pressure on the growth rate and quality of the diamond films were systematically studied. It is found that the diamond film with the best quality is synthesized by adopting a filament power of 1 600 W, a methane/hydrogen flux ratio of 18/300 (nucleation stage) and 14/300 (growth stage), and a reactive pressure of 4 kPa. The corresponding growth rate is 1.4 μm/h.

Copyright of Journal of Shanghai Jiaotong University (Science) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The high-concentration N doping of diamond film is still a challenge since nitrogen is limited during diamond growth. In this work, a novel method combined with the thermal decomposition of silicon nitride was proposed to form the activated N and Si components in the reactor gas that surrounded the substrate, with which the high-concentration N and Si doping of diamond film was performed. Meanwhile, graphene oxide (GO) particles were also employed as an adsorbent to further increase the concentration of the N element in diamond film by capturing the more decomposed N components. All the as-deposited diamond films were characterized by scanning electron microscopy, energy dispersive spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. For the pure diamond film with a growth time of 0.5 h, the N and Si concentrations were 20.78 and 41.21 at%, respectively. For the GO-diamond film, they reached 47.47 and 21.66 at%, which set a new record for super high-concentration N doping of diamond film. Hence, thermal decomposition for the substrate can be regarded as a potential and alternative method to deposit the chemical vapor deposition (CVD) diamond film with high-concentration N, which be favorable for the widespread application of diamond in the electric field. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The micron-scale diamond film was prepared using hydrogen and methane as the mixed gas supplies via self-developed 3 kW/2,450 MHz microwave plasma chemical vapor deposition (MPCVD) equipment. On this basis, the evolution of the surface morphology, hydrophobicity, and electrical properties of samples under different hydrogen plasma etching times was investigated. The results indicate that the crystal edge and the top of the diamond grain were preferentially etched when etching time is less than 30 min. The surface roughness reduced from 0.217 to 0.205 μm, and the resistance value decreases from 3.17 to 0.35 MΩ. However, as the etch time increases to 120 min, the etching depth increases, and the surface roughness was increased. Simultaneously, the contact angles increased from 62.8° to 95.9°, which indicates that the surface of the diamond films exhibits more pronounced hydrophobicity. The treatment time of hydrogen plasma has no significant effect on the resistance value in the range of 0.26–0.50 MΩ. The mechanism of surface etching by hydrogen plasma was also discussed.

Micro-diamond film, nano-diamond film and diamond-graphite composite film were deposited on silicon carbide substrate by hot filament chemical vapor deposition. The surface morphology and phase of the grown diamond films were analyzed using scanning electron microscope, atomic force microscope and Raman spectrometer. The friction coefficient and the wear rate of diamond films were measured by friction experiments. The friction and wear properties of diamond films were studied by comparing the experimental results. The results show that the diamond-graphite composite film has better friction and wear properties, the surface roughness of which is 53.8 nm. The friction coefficient (0.040) is similar to that of the nano-diamond film (0.037), while the wear rate is the lowest, 2.07×10−7 mm3·N−1·m−1. Compared with those of SiC substrate, the wear rate (9.89×10−5 mm3·N−1·m−1) and the friction coefficient (0.580) of the diamond films have been greatly improved, which indicates that depositing diamond on the surface of SiC substrate significantly improves the performance of the silicon carbide in the field of friction.

Negatively charged Silicon-vacancy (SiV-) centers in diamond have great potential for optical sensing and bio-imaging applications. Therefore,developing a large-scale and cost-effective way of fabrication of SiV- centers is of great importance to promote their applications. Here, we report a method for large-scale fabrication of SiV- centers in a diamond membrane by using MeV Helium ion implantation. The diamond membrane is highly flexible with a thickness of 10 μ m, made from a CVD diamond-on-Si wafer. By implanting the Helium ions on the nucleation side of the membrane followed by thermal annealing, we demonstrate the fabrication of a sub-micron thick SiV- layer in the surface region. Despite the polycrystalline structure of the diamond membrane, the SiV- centers exhibit a fluorescence lifetime of 1.08 ns, comparable to the SiV- centers fabricated in single crystal diamonds. By using a focused ion beam and varying the ion fluence, we demonstrate patterning of the SiV- centers of different densities. Due to the wafer-size and high flexibility of the diamond membrane and a good emission intensity of the SiV- centers, our method has great potential for making large-scale SiV- based diamond devices for applications such as bio-imaging or sensing. [Display omitted] [ABSTRACT FROM AUTHOR]

At present, the technology of obtaining diamond films on silicon and other substrates is well studied. However, in all published works to date, there has been no report of a layer of silicon carbide formed between the diamond film and the silicon substrate. The presence of a layer (15R-Si?)1-x(Cdiamond)x in the structure was revealed in the studies of structures with a diamond film obtained by us on silicon substrates by chemical vapor deposition. Diamond films were obtained on single-crystal silicon substrates with (111) orientation and n-type conductivity by the well-known CVD technology in a hydrogen-methanol (CH3OH) mixture with the addition of a certain amount (know-how) of ammonia (NH3). The diamond films consisted of small single crystals 3-5 µm in size, closely interlocked and constituting a continuous film. When studying the current-voltage characteristics of structures created on the basis of the obtained diamond films, a blue-white glow with a blue-violet tint was observed, which is explained by the mixing of blue-violet photons with photons re-emitted in the diamond film. [ABSTRACT FROM AUTHOR]

The current state of research on the use of CVD diamonds in diamond tools is reviewed. Features of single crystal and polycrystalline CVD diamonds and CVD diamond films are shown. Their comparative properties are given. Their structure and the peculiarities of processing their surfaces are shown. Technological features of the preparation of diamond tools with a working layer of CVD diamonds and the use of such tools are discussed. Samples of polycrystalline CVD diamonds for the dressing tool and features of their application in the dressing rollers are shown. [ABSTRACT FROM AUTHOR]

The high-concentration N doping of diamond film is still a challenge since nitrogen is limited during diamond growth. In this work, a novel method combined with the thermal decomposition of silicon nitride was proposed to form the activated N and Si components in the reactor gas that surrounded the substrate, with which the high-concentration N and Si doping of diamond film was performed. Meanwhile, graphene oxide (GO) particles were also employed as an adsorbent to further increase the concentration of the N element in diamond film by capturing the more decomposed N components. All the as-deposited diamond films were characterized by scanning electron microscopy, energy dispersive spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. For the pure diamond film with a growth time of 0.5 h, the N and Si concentrations were 20.78 and 41.21 at%, respectively. For the GO-diamond film, they reached 47.47 and 21.66 at%, which set a new record for super high-concentration N doping of diamond film. Hence, thermal decomposition for the substrate can be regarded as a potential and alternative method to deposit the chemical vapor deposition (CVD) diamond film with high-concentration N, which be favorable for the widespread application of diamond in the electric field.

The demand for synthetic diamonds and research on their use in next-generation semiconductor devices have recently increased. Microwave plasma chemical vapor deposition (MPCVD) is considered one of the most promising techniques for the mass production of large-sized and high-quality single-, micro- and nanocrystalline diamond films. Although the low-pressure resonant cavity MPCVD method can synthesize high-quality diamonds, improvements are needed in terms of the resulting area. In this study, a large-area diamond synthesis method was developed by arranging several point plasma sources capable of processing a small area and scanning a wafer. A unit combination of three plasma sources afforded a diamond film thickness uniformity of ±6.25% at a wafer width of 70 mm with a power of 700 W for each plasma source. Even distribution of the diamond grains in a size range of 0.1–1 μm on the thin-film surface was verified using field-emission scanning electron microscopy. Therefore, the proposed novel diamond synthesis method can be theoretically expanded to achieve large-area films. [ABSTRACT FROM AUTHOR]

In this research, the interaction mechanism between H and CH3 of chemisorption on diamond (100)-2 × 1 surface was studied through the density functional theory (DFT) method. The H or CH3 adsorbates were assumed to be directly chemisorbed to the final position on the surface in thermodynamic studies. The adsorption energies of individual H and CH3 chemisorbed on the diamond surface were calculated, respectively. Subsequently, the adsorption energies for another H or CH3 in five different positions adjacent to the initial H or CH3 were calculated and compared. We find the universal law of the most likely chemisorption position. The results revealed that when one carbon atom of the dimer chemisorbed one radical, the other carbon atom of the dimer generated a dangling bond and had more ability to chemisorb other radicals. Therefore, the growth rate is faster along the direction of the carbon dimer than in other directions during the growth of the diamond film. The dimer is exactly towards the [110] direction. As films thicken, diamond tends to grow along the [110] direction. Therefore, it could explain that the [110] texture appears easily in the experiment. And, the results can be used to analyze the detailed process relative to the growth of the diamond film. [ABSTRACT FROM AUTHOR]

High-quality diamond prepared by microwave plasma chemical vapor deposition (MPCVD) has application prospects in many high-precision fields. The film deposition experiments were carried out using microwave power 9 kW. The chamber pressures are 13 kPa, 14 kPa, 15. 5 kPa, and 17 kPa, respectively. It was found that the deposited films under pressure of 15. 5 kPa and 17 kPa exhibit abnormal growth in the central region, which is manifested as an obvious stepped bulge in the center. Surface morphology and film quality of the film were analyzed by SEM and Raman in order to reveal the reason for the abnormal deposition in the center of the film. Meanwhile, the deposition process was modeled, the power density and flow field distribution were calculated and analyzed by numerical simulation. The results show that at the same power, increasing the chamber pressure and compressing the plasma will lead to more dense growth in the central region of the film than that in the edge region and obvious steps in the central region of the diamond film, due to the short mean free path and insufficient diffusion capacity. The overall growth rate, uniformity and quality of the film will decrease after exceeding pressure limit. [ABSTRACT FROM AUTHOR]

Diamond shows great potentials as an ultimate material candidate for application in microelectromechanical systems (MEMS). In this work, we report microcontact printing (μCP) transfer as a facile technique to fabricate diamond MEMS cantilever arrays. We started from the Deryaguin–Landau–Verwey–Overbeek (DLVO) principles and formulated a colloidal "ink" that contains nanodiamonds (NDs) seeds well dispersed in polymethyl methacrylate/acetone. The NDs seeds were then transfer printed onto a silicon (100) substrate by using a flexible polydimethylsiloxane (PDMS) stamp with predefined pattern. The densely packed NDs pattern (∼109 cm−2) enables facile and selected-area growth of diamond with microwave plasma chemical vapor deposition (MPCVD) technique. A diamond film with minimal graphite contaminants and low residual stresses was obtained after growth at 1118 K for 3 h. The diamond cantilevers were released from the substrate by wet chemical etching using KOH (40 % wt.) and isopropyl alcohol (10 % vol.). An examination of the vibrational kinetics indicates that the diamond film has a high Young's modulus (∼795 GPa) and the cantilevers exhibit consistently distributed resonant frequencies and high quality factors in ambient air. The method opens the door for large-scale, cost-effective production of uniform diamond MEMS devices for sensor and quantum applications. [Display omitted] • Nanodiamonds is well dispersed in polymethyl methacrylate/acetone. • Diamond MEMS cantilevers is fabricated by using microcontact printing. • Diamond MEMS cantilevers exhibit consistently distributed resonant frequencies. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polycrystal diamond films were synthesized on high concentration alloys (HCAs) by microwave plasma chemical vapour deposition. It was found that the continuous diamond films formed in a short period, e.g., 10 min. The carbides including the stable MC [0 1 1] (M = Mo, Nb, Ta, Ti and Zr) and metastable carbides (e.g., Mo 2 C, Ti 2 C and Mo 3 C 2) were identified by X-ray diffraction and transmission electron microscopy. The diamond/carbide interface had an orientation relationship as [0 1 1] Diamond //[0 1 0] Mo2C. The hardness of MoHfNbTaTiZr HCA at the CH 4 concentration of 9% for 20 min was as high as 1238.2 HV 0.3. The friction coefficient was 0.56–0.73 for the specimens with continuous diamond films. No spallation of films after friction indicated good wear resistance and adhesion. • Continuous diamond films were deposited efficiently on high concentration alloys by CVD. • The mixed-carbides layer including the stable and metastable was formed on high concentration alloys. • The hardness was as high as 1238.2, which increased to 2.6 times than HCA substrate. • The specimen of a continuous diamond film had superior friction properties. [ABSTRACT FROM AUTHOR]

Two kinds of diamond films with completely different morphologies were prepared on N-type heavily doped silicon wafers by microwave plasma chemical vapor deposition (MPCVD) method, namely, micron-scale large grain polycrystalline diamond film dominated by (220) crystal plane (220DF) and nano-scale small grain polycrystalline diamond film dominated by (111) crystal plane (111DF). And WS 2 quantum dot powder was obtained by aqueous liquid phase ultrasonic method. Then, the 111DF/WS 2 quantum dot composite structure film (111DWSF) and 220DF/WS 2 quantum dot composite structure film (220DWSF) were prepared by applying WS 2 quantum dot powder uniformly on diamond film substrate. The results of electroluminescence (EL) detection show that the 220DWSF device emits visible blue light, and the main peak of EL spectrum is located at 443 nm in the blue region. The 111DWSF device emits white light, and the corresponding EL spectra show strong emission peaks in the blue region (454 nm), green region (536 nm) and red region (632 nm) respectively, meanwhile, the luminous intensity of 111DWSF device is much higher than that of 220DWSF device. In addition, it is also found that the 220DWSF EL device does not show obvious rectification characteristics, while the 111DWSF EL device has obvious rectification characteristics. After FN fitting of the IV characteristic curve of 111DWSF EL device, the tunneling characteristics of electrons are found in the region of high electric field intensity. [Display omitted] [ABSTRACT FROM AUTHOR]

Deposition of a consistent diamond coating on intricate surfaces has historically posed a difficulty. This article presents the advancement in research on depositing a uniform diamond coating on three-dimensional (3D) silicon spheres, utilizing a faraday cage within a microwave plasma chemical vapor deposition (MPCVD) reactor. A self-consistent three-dimensional multi-physics field model has been established for simulating the microwave electric field and plasma inside a reactor with or without a faraday cage. Results indicate the cage effectively reduces the discharge at the top of the silicon sphere and improves uniformity of the distribution of the microwave electric field and plasma electron density on the sphere's surface. MPCVD trials have demonstrated that a powerful discharge takes place at the apex of the silicon sphere resulting in an excessive thermal gradient if the cage is not added. The apex of the silicon sphere is covered with a blend of diamond and graphite phases. Due to the excessive internal stress of the coating, approximately 50 % of the samples experience coating detachment. After the addition of the cage, the strong discharge is transferred to the top of the cage, effectively suppressing the microwave electric field and plasma inside the cage. Improved quality, reduced internal stress, and enhanced uniformity of the polycrystalline diamond coating are achievable on the silicon spheres within the cage. Moreover, this technique offers a novel approach to coat diamond on complex 3D geometries. [Display omitted] • Three-dimensional multi-physics modeling verifies that faraday cage suppresses microwave electric field and plasma. • The Faraday cage improves the uniformity of the distribution of microwave electric fields and plasma in the internal space. • Uniform, high crystal quality, low stress diamond coating. [ABSTRACT FROM AUTHOR]

The demand for synthetic diamonds and research on their use in next-generation semiconductor devices have recently increased. Microwave plasma chemical vapor deposition (MPCVD) is considered one of the most promising techniques for the mass production of large-sized and high-quality single-, micro- and nanocrystalline diamond films. Although the low-pressure resonant cavity MPCVD method can synthesize high-quality diamonds, improvements are needed in terms of the resulting area. In this study, a large-area diamond synthesis method was developed by arranging several point plasma sources capable of processing a small area and scanning a wafer. A unit combination of three plasma sources afforded a diamond film thickness uniformity of ±6.25% at a wafer width of 70 mm with a power of 700 W for each plasma source. Even distribution of the diamond grains in a size range of 0.1–1 μm on the thin-film surface was verified using field-emission scanning electron microscopy. Therefore, the proposed novel diamond synthesis method can be theoretically expanded to achieve large-area films.

Phosphorus is regarded as the best substitutional donor for n-type diamonds. However, because of vacancy-related complexes, H-related complexes, and other defects in P-doped diamonds, obtaining n-type diamonds with satisfying properties is challenging. In this report, PV and PVH complexes are studied in detail using density function theory (DFT). The formation energy reveals the possibility of emergency of these complexes when doping a single P atom. Although vacancies have difficulty forming on the surface alone, the presence of P atoms benefits the formation of PV and PVH complexes and significantly increases crystal vacancies, especially in (111) diamond surfaces. Compared to (111) surfaces, PV and PVH complexes more easily form on (001) surfaces. However, the formation energies of these complexes on (001) surfaces are higher than those of doping P atoms. Studying the structural deformation demonstrated that both constraints of the upper and lower C layers and forces caused by structural deformation prevented doping P atoms. By analyzing the bond population around these dopants, it finds that the bond populations of P–C bonds of PVH complexes are larger than those of PV complexes, indicating that the PV complexes are not as stable as the PVH complexes. [ABSTRACT FROM AUTHOR]

Density functional theory ( DFT ) plane wave pseudopotential method was used to study the structural changes of diamond when hydrogen impurities were located at three different sites in the s ubsurface of hydrogen te rminated diamond films, and the difficulty of hydrogen atom adsorption on the three kinds of diamond films. Meanwhile, the transition state sea rch of surface activation reaction was carried out. All work is to explore the influence of hydrogen impurities in the subsurface of diamond films on surface activation during chemical vapor deposition ( CVD ) . The results show that: during the growth process, the structure of diamond near hydrogen impurities in subsurface is distorted, and the surface structure of diamond has an effect on the degree of distortion. The adsorption ene rgy of hydrogen atom on the three kinds of diamond films containing hydrogen impurities are little different from that of ideal diamond film. However, the energy barrier of the active sites generated is lower than that of the ideal diamond films, which is related to the phenomenon that the hydrogen impurities in the subsurface make the diamond films have P-type semiconductor characteristics. The results show that the formation rate of surface active sites can increases as hydrogen impurities entering the subs urface of the film in hydrogen rich reaction atmos phere. [ABSTRACT FROM AUTHOR]

SiC is always produced forming diamond/SiC composite films owing to the oversaturated doping of Si atoms during the preparation of high emission SiV centers. As a higher refractive index material (n = 2.72), the presence of SiC could possibly lead to inefficient photo-luminescent (PL) collection of SiV centers with total internal reflection. In order to understand such effect, different diamond/SiC films were deposited in a 915 MHz microwave plasma CVD (MPCVD) using the reactive gas of tetramethylsilane (TMS). The microstructure and photoluminescence of SiV centers were systematically investigated. It is found that the addition of TMS gas leads to the formation of cubic β-SiC and the refinement of diamond crystals. At the TMS gas flow of 5 sccm, the concentration of β-SiC is about 10% and the average diamond size is about 98 nm. The film exhibits the optimized PL emission of SiV centers, with the ratio of SiV PL to diamond Raman peak being 21.4. Increasing TMS gas flow leads to the increase of the concentration of β-SiC and the deterioration of PL emission of SiV centers. These results reveal that the introduction of TMS gas at a low flow advances the formation of diamond/SiC film containing high-brightness SiV centers. The diamond/SiC composite film at SiC concentration of 10% exhibits the optimized PL collection of SiV centers (the 2# sample). Image 1 [ABSTRACT FROM AUTHOR]

Microwave plasma chemical vapor deposition (MPCVD) is an important method for synthesis of high-quality diamond film due to its high plasma density, good controllability and high cleanliness in the deposition process. Based on the theory of resonant cavity and three-dimensional full-wave electromagnetic field simulation, the microwave plasma cavity, mode converter and substrate holder shapes, which have a great influence on microwave coupling efficiency and electric field distribution, were designed and optimized. By testing and monitoring the key parameters in the microwave transmission system, influence of the tuning variables on diamond deposition were analyzed. With the MPCVD device proposed in this paper, high quality diamond films were deposited with an effective circular growth area with a diameter of 50 mm at a growth rate of 10 µm/h to 25 µm/h. The characterization results show that the single crystal diamond films have optical transmittance close to theoretical threshold and an excellent crystalline structure, with low impurity contents of nitrogen and silicon. [ABSTRACT FROM AUTHOR]

This study is focused on the tribological properties of micro- and nano-crystalline diamond (MCD and NCD), non-hydrogenated and hydrogenated diamond-like carbon (DLC and DLC-H) and nitrogen-based (CrN, TiN and TiAlN) coatings sliding against the super alloy Inconel 718, in terms of the maximal and average coefficients of frictions (COFs), the worn morphologies and the specific wear rates, by the rotating ball-on-plate configuration under dry condition. The results show that the nitrogen-based films show comparable COFs and wear rates with the WC–Co substrates. The DLC and DLC-H show lower COFs compared with the nitrogen-based films. Furthermore, their wear resistance is limited due to their low thickness compared with MCD and NCD, which have the same elemental composition. The DLC-H coating exhibits much lower wear rate compared with the DLC coating, which may be derived from the passivation of dangling bonds by the linking of H to C atoms. The MCD and NCD films show the lowest average COFs and mild wear after tribotests, due to their high hardness and low adhesive strength between pure diamond and the super alloy. Among all the tested films, the NCD film-based tribopair presents the lowest maximal and average COFs, tiny wear debris particles, mild wear of ball and plate without scratching grooves, indicating that the NCD film may be suitable to be deposited on cutting tools for super alloy machining. [ABSTRACT FROM AUTHOR]

The process of deposition of allotropic modifications of carbon from the gas phase (5 vol % methane) with the use of microwave plasma on W wire 20 μm thick has been studied. The microwave power was changed in the range from 3 to 5 kW. The investigations of the structure of coatings, as well as the results of Raman spectroscopy, made it possible to establish that a microwave power of 3 kW results in the deposition of a diamond film with a crystallite size from 1 to 5 μm, microwave power of 4 kW causes the deposition of diamond-like carbon, and an increase in power up to 5 kW leads to the deposition of multigraphene film. [ABSTRACT FROM AUTHOR]

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 Eu-containing nanoparticles show high-intensity orange narrow-band photoluminescence near the wavelength of 612 nm. Using β-NaGdF4:Eu instead of Eu-(III) tri-(2,6-pyridine dicarboxylic acid) and europium fluoride in the diamond matrix resulted in enhanced signal/noise ratio in the luminescence. The mapping of the spatial distribution of photoluminescence intensity on macro- and micro scale revealed highly uniform emission originated from the composite. The developed composite material with mechanically strong, highly thermally conducting and transparent diamond matrix opens a way to use the diamond–fluoride composites as photo- and X-ray luminescent screens (scintillators) capable to withstand high photon fluxes. [ABSTRACT FROM AUTHOR]

The contact interface structure of the diamond film/metal directly affects its application in the field of microelectronic devices. Good ohmic contact and strong bonding force are the keys to determining the performance of diamond thin film electronic devices. The interface model of different metal (gold, titanium, copper, aluminum, and tungsten) /hydrogen-terminated diamond (100) substrates was constructed by first-principles method based on density functional theory, and the bonding properties were studied. The results show that all metal/diamond interfaces exhibit a stable interfacial structure, but the bonding energy of gold, copper, and aluminum metals to hydrogen-terminated diamond substrates is lower, the metal layer is less relaxed, the charge has no obvious transfer on the adsorption surface, and the bonding energy is weak. In contrast, tungsten, titanium have better bonding strength and higher bonding energy with hydrogen-terminated diamond surface, and the metal layer exhibits a significant relaxation phenomenon, showing a strong interface bonding force. [ABSTRACT FROM AUTHOR]

The electrical power consumption, which is approximately equal to the thermal budget, accounts for the majority of the total cost to synthesize diamond films by the hot filament chemical vapor deposition (HFCVD) apparatus. In this study, two strategies, visualizing as certain additional parts in the apparatus, are proposed for reducing the thermal budget and synthesis cost. Detailed effects are proven by the finite volume method (FVM) simulation, temperature measurement and deposition experiments, demonstrating that the reduction of thermal conductivity of the worktable (by changing the worktable material) and the insertion of the circular ring copper shielding will significantly contribute to the reduction of the heat dissipation and substrate temperature rise. Influences of major filament parameters on substrate temperature values and distributions are then clarified, suggesting that in order to control the substrate temperatures in a similar and reasonable range in the modified apparatus, the best choice is to synchronously reduce the filament diameter and the electrical power, while retaining the filament temperature still in a high level (around 2200 °C). Finally, the energy saving ratios are as high as 28.4% (experimental apparatus) and 27.4% (commercial apparatus), and the substrate temperature distributions can also be improved, guaranteeing the uniformity of as-deposited diamond films on mass substrates. [Display omitted] • Two strategies are proposed for reducing the thermal budget and synthesis coast of HFCVD diamonds. • Thermal conduction from worktable to cooling water is reduced by changing worktable material. • Thermal radiation from filaments to water-cooled wall is reduced by inserting copper shielding. • Filament diameter and electrical power should be both reduced to obtain appropriate temperatures. • Energy saving ratios are as high as 28.4% (experimental apparatus) and 27.4% (commercial apparatus). [ABSTRACT FROM AUTHOR]

A low-temperature brazing method of diamond and Cu was proposed by using composite filler of Au-Si eutectic + NiTi particle. Prior to joining, diamond surface was modified by an active alloy of AgCu28 +TiH 2 , the resulting Ag-Cu coating could ensure the good wettability of Au-Si filler during brazing and formed TiC layer could ensure a tight interfacial bonding. In the brazing process, it was found that melting point depressant element of Si in Au-Si filler could be completely consumed by (i) reacted with NiTi alloy and formed NiTiSi whiskers and (ii) precipitation in form of Ti 5 Si 3 C and TiCuSi in modified layer, while the interdiffusion between Au and Cu substrate lead to a ductile seam matrix of heat-resistant (Au, Cu)ss. Attributed to the excellent plasticity and high melting temperature of (Au, Cu)ss and the strengthening effect of NiTiSi whiskers, the joint brazed at 600 ℃ not only have a high shear strength of 108 MPa at room temperature, but also exhibited a excellent heat-resistance, the joint showed a shear strength of 89 MPa and 28 MPa at 300 ℃ and 500 ℃, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ti-coated diamond wheel was used to mechanochemically grind diamond film. • Vacuum micro-evaporation coating technique was employed to deposit Ti on diamond. • A diamond-TiC-Ti structure was formed on micro-diamond abrasives. • Ti coating on protruding diamond abrasives enhanced material removal rate. • Ti reacted with diamond film and facilitated graphitization at contact locations. The outstanding hardness and wear resistance of diamond materials pose significant challenges in their grinding processes for semiconductor substrate materials. To overcome this, a mechanochemical effect-based approach is used, which employs a grinding wheel comprising titanium (Ti)-coated diamond abrasives. A uniform Ti coating is vacuum-evaporated onto micrometer-scale diamond abrasives. The coating layer forms a diamond-TiC-Ti structure extending from the diamond matrix to the Ti coating direction. The material removal rate (MRR) of the DF is significantly increased as a result of the protruding active Ti coating on the diamond abrasives reacting with the DF at the interface contact locations. Increasing the grinding speed from 300 rpm to 700 rpm under a fixed grinding pressure of 300 N results in an MRR increment from 32 nm/min to 913 nm/min. Similarly, maintaining a grinding speed of 600 rpm while increasing the grinding pressure from 300 N to 600 N leads to an MRR increase from 388 nm/min to 1662 nm/min. The primary mechanism behind material removal is the reaction between the Ti coating and the DF, as well as the graphitization of the DF. [ABSTRACT FROM AUTHOR]

In this work, the diamond films with 150 mm in diameter were prepared in our home-made 915 MHz microwave plasma chemical vapor deposition (MPCVD) system. The appropriate height of the pocketed substrate holder was researched in order to reduce the edge effect as much as possible. And the diamond thin films which were deposited in the designed substrate holder present relative high uniformity which demonstrated the feasibility of the structure of the substrate holder. Furthermore, the φ 150 mm diamond thick film was deposited using relative higher gas mixture flow rate and microwave power. The thickness variation of the diamond thick film is about 13.4% and the full width at half maximum (FWHM) of the diamond peak increases from 5.78 cm−1 to 7.23 cm−1 with the distance to the center of the diamond film increasing from 0 mm to 70 mm. The I(C 2)/I(H α) across the plasma shows a relative uniform distribution which was kept in the range of 2.9–3.4 in our experiments. Besides that, the φ 200 mm diamond film was attempt to synthesis which illustrates the feasibility of depositing the diamond films with the diameter more than 150 mm, although some improvements on the plasma environment should be considered. • The height of the substrate holder was researched. • The uniform diamond thin and thick films with 150 mm in diameter were prepared. • The plasma for the deposition of large area diamond films was diagnosed. • Some previous researches were carried out in the deposition of φ200 mm diamond film. [ABSTRACT FROM AUTHOR]

The excellent properties of diamond make it a highly promising substrate material for future sensors and semiconductor devices. The surface roughness of the substrate material directly impacts the performance of the devices. Therefore, achieving efficient and low-damage processing of diamonds is crucial. However, diamond has high hardness and chemical inertness, which makes it difficult to process. To tackle the above-mentioned problem, the diamond film was ground using a grinding wheel containing nickel (Ni)-plated diamond abrasives based on the mechanochemical effect. The maximum average material removal rate of the diamond film reached 2469 nm/min under a grinding pressure of 600 N at a speed of 600 rpm, and the minimum average surface roughness of the diamond film reached 3.93 nm under 500 N 600 rpm. The rapid reaction removal of the diamond film can be attributed to the catalytic effect of the Ni plating, inducing graphitization of the diamond film at the interface contact points under the generated high temperature during friction; subsequently, it can be removed under the mechanical action of the abrasives. This work has tremendous potential for the efficient and low-damage grinding of diamond films. [Display omitted] • Ni-plated diamond abrasives were used to mechanochemically grind diamond film. • Ni plating was prepared on diamond abrasives by palladium-free electroless plating. • Ni plating induced graphitization of diamond film at interface contact points. • Max average material removal rate was 2469 nm/min. • Min average surface roughness was 3.93 nm. [ABSTRACT FROM AUTHOR]

Diamond has significant advantages in the future application of semiconductor devices due to its excellent properties. Therefore, achieving efficient and low-damage processing of diamonds is crucial. However, processing diamonds is extremely challenging due to their high hardness and chemical inertness. To overcome this challenge, we propose a novel method to expedite the grinding diamond films based on mechanochemical effect. Specifically, a grinding wheel containing Cr-coated diamond abrasives was employed to achieve the rapid grinding of diamond film. The reason for the rapid reactive grinding of diamond film is that the Cr coating on the diamond abrasives reacted with the diamond film in situ to form carbide while facilitating graphitization of diamond film at the contact points at high temperatures due to friction. The results indicated that the Cr-coated diamond grinding wheel exhibited a higher material removal rate (MRR) compared with the uncoated diamond grinding wheel. The maximum MRR of the diamond film reached 1438 nm/min under the grinding condition of 700 N 600 rpm, and the minimum surface roughness of the diamond film reached 35.8 nm under 600 N 600 rpm. This mechanochemical grinding method provides an innovative approach for efficient and precise processing of hard and difficult-to-machine new-generation semiconductor materials. • Cr-coated diamond wheel was used to rapidly grind diamond film. • Cr-coated diamond abrasives were prepared by Vacuum micro-evaporation coating • In-situ reaction of Cr coating with diamond film led to rapid removal. • Cr coating facilitated graphitization of diamond film due to friction. [ABSTRACT FROM AUTHOR]

A composite model, which combined diamond thin film with surface microstructure, was designed on the surface of silicon carbide by picosecond laser and hot filament chemical vapor deposition. And the multifunctional friction and wear tester was used to study the tribological performance of the friction pair (silicon carbide-graphite) under oil-poor conditions to examine the tribological performance of the friction pair in terms of surface temperature rise and time-varying wear. The results show that the friction coefficient under the composite modeling of surface microstructure and diamond film reaches 0.009, and at the same time, the surface temperature of the composite modeling is only 61.2 ℃, which is 5.1% lower than that of only diamond film and 62.1% lower than that of no surface treatment, which indicates that the high frictional heat has caused a significant graphitization transition in the film. And the surface of the friction sub-surface with the lowest temperature (surface microstructure and diamond thin film composite modeling) kept the carbon content at more than 90% without the formation of Si-C bonding, which guaranteed the complete carbon friction transfer film; At the same time, the I D /I G ratio of the friction surface under the composite modeling of the surface microstructure and diamond film is about 0.06 at the abrasion mark, the I D /I G ratio of the diamond film only is about 0.33, and the I D /I G ratio of the friction surface without any surface treatment is about 1.37. Transient high temperatures lead to abrasion and localized spalling on the surface of friction pairs, causing graphite oxidation to become progressively more severe, thus transforming abrasive wear into adhesive wear. As a result, double composite surface configuration with diamond film and laser texture further reduced the transient temperature rise of the surface and improved the tribological performance of the friction pairs. • The article studies the tribological properties of friction pairs under diamond film and laser textured composite surfaces. • The friction performance of friction pairs was investigated from the point of view of transient temperature rise. • The formation of an oxide layer and the gradual worsening of graphitization lead to the appearance of adhesive wear. [ABSTRACT FROM AUTHOR]