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This article describes observation of n-type conductivity for chemical vapor deposition (CVD) diamond films annealed by using 4-MeV Si2+ ion-beam irradiation at a low temperature of 660 °C. Although CVD diamond films grown on the High-Pressure High-Temperature (HPHT) Ib-substrates showed excellent crystallinity, these films were unintentionally auto-doped with highly concentrated N atoms. At first, n-type conductivity had not been judged for the as-grown state. However, after irradiation by 4-MeV Si2+ ions at 660 °C, the grown diamond film exhibited clear and stable n-type conductivity at a relatively low temperature of 250 °C. This fact was ascertained by measuring the electrical conductivity with a Hall effect apparatus. The as-purchased HPHT Ib-substrate after a normal RCA cleaning processes exhibited evident n-type conductivity at above 300 °C due to intrinsically contained dopant N atoms in the substrate. On the other hand, the as-grown CVD film deposited on the Ib-substrate exhibited evident n-type conductivity at a thoroughly lower temperature of 250 °C after 4-MeV Si2+ irradiation. 250 °C temperature is lower than 300 °C for the as-purchased HPHT Ib-substrate. Theoretical simulations were performed to fit Hall-measured data of sheet resistivity and sheet carrier concentration. The simulation results were based on the charge neutrality principles. The author also proposed novel activation energy of N atoms in diamond semiconductors to be 2.5 eV, which is much larger than formerly reported values of 1.4–1.7 eV. Lastly, the author discussed the possibility of MeV-ion irradiations being as novel and useful annealing technology for heavy type-n-dopants ion implantations into diamond semiconductors. [ABSTRACT FROM AUTHOR]

The morphology and crystalline quality of polycrystalline diamond samples were studied by systematically varying the flowrate of nitrogen gas in the microwave plasma. A slight improvement in both crystallite size and crystalline quality is observed for a low concentration of 0.5 sccm nitrogen. With a further increase in nitrogen concentration, diamond switches from micro-crystalline to nanocrystalline (NCD) with a nitrogen flow of 2.5 sccm (10% of methane concentration). The surface roughness of the sample is found to depend strongly on the crystallite size of the sample. Extensive spectroscopic studies have been done to understand the presence and formation of different defect complexes in diamond. XPS and Raman analysis of the films reveal the variation of graphitic content as a function of nitrogen addition. The presence of nitrogen-containing defect complexes has been studied thoroughly and their concentration has been found to be limited by the solubility limit rather than the availability of reactants in the gas environment. In contrast, the effect these complexes have on the strain of the diamond film is found to be negligible. Optical emission spectroscopy of the plasma reveals the presence of C2 dimers as well as C-N radicals. However, they have little role in modifying diamond grain morphology or crystalline quality. [ABSTRACT FROM AUTHOR]

With the miniaturization of electronic devices, thermal management has become a critical challenge, especially for high-power systems where efficient heat dissipation is essential. Polycrystalline diamond films, renowned for their exceptional thermal conductivity, offer a promising solution. However, the thermal boundary resistance (TBR) at the diamond/substrate interface remains a significant bottleneck, severely impacting heat dissipation efficiency. This study presents a measurement approach tailored for quantifying TBR in thick-film diamond heterostructures, focusing on diamond-on-silicon (Diamond-on-Si) systems with a silicon nitride barrier layer. Compared to conventional methods, such as transient thermoreflectance techniques, which often exhibit limited sensitivity for thick layers, this approach demonstrates greater reliability and applicability. The findings establish a foundation for advancing strategies to reduce TBR and improve the thermal management performance of diamond films in high-power electronic applications. [ABSTRACT FROM AUTHOR]

With the development of diamond technology, its application in the field of electronics has become a new research hotspot. Hydrogen-terminated diamond has the electrical properties of P-type conduction due to the formation of two-dimensional hole gas (2DHG) on its surface. However, due to various scattering mechanisms on the surface, its carrier mobility is limited to 50–200 cm2/(Vs). In this paper, the effects of process parameters (temperature, CH4 concentration, time) on the electrical properties of hydrogen-terminated diamond were studied by microwave plasma chemical vapor deposition (CVD) technology, and hydrogen-terminated diamond with a high carrier mobility was obtained. The results show that homoepitaxial growth of a diamond film on a diamond substrate can improve the carrier mobility. Hydrogen-terminated diamond with a high carrier mobility and low sheet resistance can be obtained by homoepitaxial growth of a high-quality diamond film on a diamond substrate with 4% CH4 concentration and hydrogen plasma treatment at 900 ℃ for 30 min. When the carrier concentration is 2.03 × 1012/cm2, the carrier mobility is 395 cm2/(Vs), and the sheet resistance is 7.82 kΩ/square, which greatly improves the electrical properties of hydrogen-terminated diamond. It can enhance the transmission characteristics of carriers in the conductive channel, and is expected to become a potential material for application in devices, providing a material choice for its application in the field of semiconductor devices. [ABSTRACT FROM AUTHOR]

ZnO/micron diamond (MCD) composite structure combines two wide-band gap semiconductor materials, providing stable performance suitable for high-performance electron field emission (EFE) devices operating in various complex environments. Nonetheless, the optical and electrochemical limitations of ZnO constrain its effectiveness. Typically, NiO can compensate these inherent defects in ZnO, thereby enhancing the performance of field-emitting devices. In this research, NiO-decorated ZnO thin films were fabricated on diamond surfaces using hydrothermal/sol-gel two-step method. The impact of varying Ni doping concentrations caused by nickel acetate solutions on the field emission properties was thoroughly investigated. Furthermore, this study involved the fabrication of NiO-decorated ZnO/micron diamond heterojunction composite structures, exploring the impact of the structure on the optoelectronic performance of the devices. The Ni doping concentration increases in the NiO films formed between the ZnO nanorods, the doped Ni exists in the ZnO/MCD composite structure as both Ni2+ and Ni3+, which are important materials for semiconductor electronic devices. The NiO decoration process induced the creation of defect levels within the bandgap of the nanorod array structure, consequently enhancing the photoluminescence performance of ZnO. Furthermore, the interaction between NiO and ZnO facilitated the formation of a p-n junction at the interface, generating an internal electric field. This electric field significantly improved the current conduction field and maximum current density of ZnO, thereby enhancing its electric field emission performance. The optical and electrical properties of ZnO nanorods doped at 0.1M exhibited the most favorable characteristics among all tested samples. At a doping concentration of 0.1 M, the turn-on electric field reaches a minimum value of 0.96 V/μm and the maximum current density J reaches a maximum value of 2.54 mA/cm2. These results offer novel insights for advancing the development of integrated broadband optical devices. [ABSTRACT FROM AUTHOR]

Telecommunication of the next generation demands filters that can operate in the 10 GHz range with sufficient bandwidths. For surface-acoustic-wave (SAW) devices this prerequisite translates into high sound velocities and high piezoelectric couplings. Wurtzite AlN on diamond, which exploits the strong piezoelectricity of AlN with the very high SAW velocity of diamond, has been considered a promising platform. A significant boost (up to a factor of 4) of the piezoelectric response can be obtained by alloying AlN with Sc. Here, the main challenge lies in the synthesis of highly-oriented thin (Sc,Al)N films on diamond. In this work, we aim at establishing a platform for SAW devices using plasma-assisted molecular beam epitaxy for the deposition of Sc0.2Al0.8N on diamond. We investigate the structural properties related to SAW generation gearing towards applications at high frequencies. To this end, we prepare (Sc,Al)N thin films on polished polycrystalline diamond wafers and demonstrate the efficient generation of SAW modes with frequencies up to 8 GHz. Systematic studies of the dependence of the SAW velocity and electromechanical coupling coefficient on the Sc0.2Al0.8N film thickness is presented for various SAW modes. Our result demonstrates the potential of this material combination for future application that requires large bandwidth in the ultra-high frequency range. [ABSTRACT FROM AUTHOR]

The electrochemical detection of two pharmaceuticals, diclofenac (DCF) and carbamazepine (CBZ), was investigated as an oxidation current using boron‐doped nanocrystalline diamond (BDD) thin‐film electrodes. Both voltammetry and flow injection analysis with amperometric detection (FIA‐EC) were used to measure the drugs in standard solutions and a urine simulant. The oxidation potential for DCF was ca. 0.7 V vs. Ag/AgCl (3 M KCl) in 0.1 M phosphate buffer (pH 7.2) and was ca. 1.2 V for CBZ in 0.1 M perchloric acid. The DCF oxidation reaction was diffusion controlled at the detection potential with evidence of some surface fouling by reaction products. The CBZ oxidation reaction was also controlled by diffusion at the detection potential, but with no surface fouling. The voltammetric peak currents for both drugs increased linearly with the concentration in the micromolar range (r2≥0.994). FIA‐EC analysis of DCF and CBZ revealed a linear dynamic range from at least 0.1 to 100 μM with the actual minimum concentration detectable (S/N=3) being less than the lowest concentration measured. The recovery percentage for DCF in the urine simulant ranged from 94–108% and from 97–100% for CBZ, both assessed using square wave voltammetry. FIA‐EC data revealed that the BDD electrodes offer excellent intra and inter‐electrode repeatability with an RSD for DCF and CBZ of 4.90% and 3.81%, respectively. The BDD electrode provided good reproducibility and response stability over eight days of continuous use detecting both DCF and CBZ. Overall, BDD electrodes are a viable material for the sensitive, selective, and reproducible electrochemical detection of these two pharmaceuticals. [ABSTRACT FROM AUTHOR]

In this work, a nanoporous ultrananocrystalline diamond film (B-UNCDWS/TDNT/Ti) was obtained and compared with a commercial electrode in the degradation of methomyl, a recalcitrant pesticide. The morphological and structural differences between the materials were highlighted by SEM and XRD analysis: while the commercial electrode presented a regular and planar surface with microcrystalline grains, supported by XRD features, the B-UNCDWS/TDNT/Ti electrode presented a porous morphology with DRX features indicating a high film renucleation rate. Those differences affected the electrooxidation of methomyl; B-UNCDWS/TDNT/Ti was responsible for faster and more economic degradation of the pollutant, achieving a methomyl degradation of 78% (against 35% by the commercial electrode). The highly porous surface of UNCDWS/TDNT/Ti provides an electrochemical area threefold greater than the one found in the commercial electrode, justifying the better efficiency in the formation of persulfate, which can be singled out as the main mechanism in methomyl degradation. [ABSTRACT FROM AUTHOR]

Integrating nanocrystalline diamond (NCD) films on silicon chips has great practical significance and many potential applications, including high-power electronic devices, microelectromechanical systems, optoelectronic devices, and biosensors. In this study, we provide a solution for ensuring heterogeneous interface integration between silicon (Si) chips and NCD films using low-temperature bonding technology. This paper details the design and implementation of a magnetron sputtering layer on an NCD surface, as well as the materials and process for the connection layer of the integrated interface. The obtained NCD/Ti/Cu composite layer shows uniform island-like Cu nanostructures with 100~200 nm diameters, which could promote bonding between NCD and Si chips. Ultimately, a heterogeneous interface preparation of Si/Ag/Cu/Ti/NCD was achieved, with the integration temperature not exceeding 250 °C. The TEM analysis shows the closely packed atomic interface of the Cu NPs and deposited Ti/Cu layers, revealing the bonding mechanism. [ABSTRACT FROM AUTHOR]

The growth of diamond film with texture on stainless steel can significantly improve its wear properties, while conventional methods such as laser etching and ultrasonic vibration superimposed machining suffered from complex processes and extra equipment. Here, we propose a simple new method to prepare textured diamond film on stainless steel without any special apparatus. In this method, a W/W-N interlayer was first deposited on the stainless steel surface, and then the sample with the interlayer was put into a hot filament chemical vapor deposition (HFCVD) chamber to grow diamond films. The interlayer becomes cracked during the warm-up stage due to the large tensile stress formed by the thermal expansion coefficient difference between the interlayer and the steel. Then the deposited diamond films copy the morphology of the interlayer, forming the textured diamond film. The textured diamond film exhibits a small amount of stress, ~3.4 GPa, and greatly improved wear resistance. Our results provide a way to prepare textured diamond films with good wear resistance. [ABSTRACT FROM AUTHOR]

To minimize the detrimental effects of cobalt binder on the thermal stability of polycrystalline diamond compact (PDC) under high temperature working conditions and enhance the PDC's properties. Hot filament chemical vapor deposition diamond coated polycrystalline diamond compact (HFCVD-PDC) was prepared by depositing homogeneous epitaxial diamond film on the polycrystalline diamond layer (PCD layer) treated with cobalt binder removal. The effect of deposition pressure on the microstructure of the diamond film was investigated, and the PDC's wear resistance was assessed using the abrasion ratio test. The drop hammer impact test was utilized to evaluate the impact toughness of the original PDC, cobalt removal PDC, and HFCVD-PDC. The results showed that a continuous and dense nanodiamond film with a cauliflower-like structure was formed on the PDC surface at the deposition pressure of 3 kPa. The abrasion ratio of the HFCVD-PDC increased by 67.44% compared to the original PDC, and by 33.29% compared to the cobalt removal PDC. Furthermore, filling nanodiamonds into the pores of cobalt removal PDC improved its impact toughness. These findings suggest that the application of homogeneous epitaxial diamond on the PCD layer can significantly improve the PDC's wear resistance and impact toughness. [ABSTRACT FROM AUTHOR]

The advent of the new 5G communication standard has introduced demanding requirements for the performance of RF front-end filters, necessitating high frequency, large bandwidth, and other improved parameters. Consequently, researchers have been actively investigating the potential of surface acoustic wave resonators and film bulk acoustic resonators to address these needs, leading to the development of numerous novel structures. Through finite element simulation, a new heterogeneous stack structure Al/LN/diamond/Si with an interdigitated electrode resonant cavity is proposed. And the advantageous role of a diamond thin film in the surface acoustic wave resonant structure, including the excitation of high-frequency acoustic resonance modes and modulation of the electromechanical coupling coefficient has been studied. This structure holds promise for addressing the increasing demands for high-frequency, large-bandwidth RF front-end filters in the context of the new 5G communication standard. The results show that the central resonant frequency of the new structure resonator is 5284 MHz, the electromechanical coupling coefficient is 10.96%, and the Q factor value is 10 316, which has potential application value in the field of high-frequency filtering. [ABSTRACT FROM AUTHOR]

For the wafer-scale fabrication of diamond devices, the growth of diamond substrates by heteroepitaxial chemical vapor deposition is the most promising option currently available. However, the transfer of growth and also structuring processes from small homoepitaxial to larger heteroepitaxial samples is not straightforward and requires adaptation. In this study, we present an approach for the fabrication of functional microstructures including pyramids and mesas as well as more complex structures with hollow centers. The associated methods were previously demonstrated by homoepitaxial growth and are now evaluated on heteroepitaxially grown diamond films. After optimizing the growth procedures to ensure a sufficient quality of the bare diamond substrates, precursor structures for overgrowth were fabricated by e-beam lithography and plasma etching. In the overgrowth of nanopillars, a truncated pyramidal shape was achieved. The characterization with scanning electron microscopy revealed the growth of higher-index facets. Nevertheless, photoluminescence spectroscopy reveals localized doping on the sides of the microstructures. In addition, optically detected magnetic resonance reaches a contrast of 6 % of one preferred nitrogen vacancy orientation per facet and a transverse relaxation time T 2 ∗ of 96 ns. [ABSTRACT FROM AUTHOR]

Ultra-nanocrystalline diamond (UNCD) films exhibit excellent mechanical properties because of their unique structure, such as small grain size and high grain boundary ratio. The effect of nitrogen atoms in nitrogen-doped UNCD films on their structure and mechanical properties deserves in-depth study. In this study, we focus on the microstructure control of UNCD films and its effect on the mechanical properties. Ultra-nanocrystalline diamond films were prepared using microwave plasma chemical vapor deposition under varying nitrogen flow rates. It was observed that the hardness and elastic modulus of UNCD films initially increased and then decreased with the increase of nitrogen flow rate. The structure of UNCD films was characterized using transmission electron microscopy and the crystal quality was analyzed through Raman spectroscopy. Nitrogen-interstitial atom defects were identified in the photoluminescence spectra. These defects contribute to shorter interatomic bonds and enhance the covalent bonds in the crystalline structure, resulting in an increase in hardness. The sp2/sp3 ratio and effective nitrogen atom concentration in the UNCD film were analyzed by X-ray photoelectron spectroscopy. The results indicate that an increase in the effective nitrogen atom concentration corresponds with a notable reduction in grain size, which is simultaneously accompanied by a rise in the number of grain boundaries. Meanwhile, the increase of sp2 content in the UNCD leads to the increase of grain boundary width and density, resulting in the increase of hardness and elastic modulus. This work provides theoretical basis and experimental guidance for the development of high performance UNCD films through precisely regulating the microstructure. [ABSTRACT FROM AUTHOR]

To address the issue of heat dissipation caused by the high output power density of gallium nitride (GaN) devices, using diamond‐integrated devices is an effective solution. Recent studies have suggested that incorporating a dielectric layer, such as silicon nitride (SiNx), between diamond and GaN can improve adhesion while also reducing thermal boundary resistance (TBR). In this study, plasma‐enhanced chemical vapor deposition (CVD), low‐pressure CVD, and metal‐organic CVD (MOCVD) techniques are utilized to grow the SiNx layer. The interface behavior of diamond/SiNx/GaN is analyzed through scanning electron microscopy, transmission electron microscopy (TEM), scanning TEM, and energy‐dispersive X‐ray spectroscopy, while time‐domain thermoreflectance measurement is used to characterize thermal properties. After analyzing the impact of the growth dielectric layer on the interface thermal resistance of the three growth modes, it is concluded that the dielectric layer produced by the MOCVD technique exhibits a smoother surface and lower TBR compared to the other two methods. Therefore, the use of the MOCVD technique is recommended to achieve optimal thermal performance in diamond/SiNx/GaN systems. [ABSTRACT FROM AUTHOR]

Optical diamond materials are essential for infrared optical windows, microwave windows, and laser windows due to their exceptional properties. However, dark features inside the diamond are significant factors limiting optical properties, particularly at high deposition rates. This work focuses on adjusting crystallographic parameters to prepare (110) oriented optical-grade polycrystalline diamond films, aiming to mitigate dark features. Diamond films deposited via microwave plasma chemical vapor deposition (MPCVD) exhibit discernible quality stratification. Characterization analysis of diamond film samples with varying levels of black defects reveals a correlation: films with higher dark feature content tend to exhibit a preference for the (111) orientation, accompanied by a significant presence of penetration twins and interstitial voids. Conversely, transparent diamond films demonstrate a prominent (110) orientation, featuring numerous contact twins that alleviate competition from penetration twins and original grains during growth. Electron backscatter diffraction (EBSD) and scanning electron microscope (SEM) results reveal that transparent diamond films cultivated with a pronounced preference for the (110) orientation manifest consistent and seamless contact twins, leading to fewer dark features and improved optical transmittance. In contrast, (111) oriented diamond film exhibits numerous penetration twins, and holes form between them. Based on the analysis, 5-inch optical polycrystalline diamond films with (110) orientation were achieved successfully by suppressing dark features. [ABSTRACT FROM AUTHOR]

The structure and properties of polycrystalline chemical vapor deposition (CVD) diamond coatings grown by microwave plasma CVD in H2–CH4 mixtures can be effectively controlled by nitrogen admixture in the process gas. Here, a comparative study of adding nitrogen from different precursors, N2 and ammonia NH3, in concentrations up to 0.4%vol on grain size, texture, surface roughness, and sp2/sp3 ratio of the produced films on Si substrates is performed. A transition from microcrystalline to smooth nanocrystalline diamond structure is found to occur at a certain concentration of the precursor, for NH3 this threshold concentration being much lower, 0.02–0.1%, than for N2. The higher activity of ammonia is associated with easier formation of cyano radicals in the plasma as detected with optical emission spectroscopy, in accord with the lower bond‐dissociation energy for NH3 compared to N2. On the contrary, a smaller addition (0.004%) of either N2 or NH3 promotes almost doubling of the growth rate, while preserving the microcrystalline structure of the film. The results establish ammonia as a convenient alternative precursor to commonly used N2 added in the plasma for the diamond film structure modifications. [ABSTRACT FROM AUTHOR]

The deposition of diamond films on tungsten carbide-based tools can greatly improve the life and performance of cutting tools. However, the deposition of diamond coatings on cemented carbide (WC-Co) suffers from poor film-base bond strength. In this paper, diamond coatings were deposited of phytocrystalline metal micropowders (pure, Nb, Ti, Ta) pretreatment method and the properties of diamond films were analyzed by energy spectrometry (EDS), scanning electron microscopy (SEM), Raman spectroscopy and bonding strength test of diamond films. The results show that through the experiment of the pretreatment process of surface implanted crystal metal micropowder, the best implanted crystal metal micropowder was obtained, the surface quality of implanted crystal titanium (Ti) coating was improved, the diamond Raman peaks were sharp and the indentation cracks had a crack diameter of 389 μm, which is small and has the highest bond strength. The pretreatment process of phytocrystalline diamond micropowder can deposit high-performance diamond coatings and improve the bonding strength between the coating and the substrate film base. [ABSTRACT FROM AUTHOR]

Doped diamond has found a commercial use for achieving durable and reproducible electrical measurements in atomic force microscopy (AFM). Yet so far it has not been used on self‐sensing AFM probes due to thermally and mechanically sensitive integrated detection circuits. Herein, conventional microwave plasma chemical vapor deposition (CVD) is employed while taking advantage of thermal conductivity along the silicon AFM cantilever probe for growing high‐quality B‐doped nanocrystalline diamond film on the probe apex that is selectively seeded by dip coating in nanodiamond solution. By investigating various CVD process parameters, it is shown that the detection circuit remains functional up to 400 °C for 2 h deposition or up to 8 h at 300 °C. Scanning electron microscopy and Raman spectroscopy corroborate quality of the diamond coating and doping. The self‐sensing probes are successfully tested in conductive AFM (C‐AFM) regime and surface spreading resistance regime, showing linear response in current–voltage spectroscopy and capability of conductivity mapping on metals and semiconductor devices. In the results, prospects for stable C‐AFM measurements when conventional optical detection is not suitable, such as on photosensitive materials or in probe‐electron microscopy, are opened. [ABSTRACT FROM AUTHOR]

Diamond is renowned as the ultimate semiconductor thanks to its exceptional physical properties, including unmatched hardness, exceptional wear resistance, superior mechanical and tribological characteristics, and high fracture strength. Diamond solution-gate field-effect transistors (D-SGFETs) leverage these advantages, along with their outstanding high-power and high-frequency performance, excellent thermal conductivity, wide bandgap, high carrier mobility, and rapid saturation speed. These features make D-SGFETs highly promising for fast and precise biomedical detection applications. This paper provides a comprehensive review of the fabrication techniques for diamond SGFETs, encompassing diamond film synthesis, surface conduction layer formation, source/drain fabrication, and FET packaging. Furthermore, the study delves into the surface functionalization of diamond SGFETs and their diverse applications in biomedical detection. Finally, the paper discusses the future outlook of diamond SGFETs in advancing biomedical detection technologies. [ABSTRACT FROM AUTHOR]

Diamond films possess numerous extraordinary physical and chemical properties, but their high-temperature applications are limited by its poor thermal stability. Herein, we fabricated the undoped microcrystalline diamond (MCD) film and heavy boron-doped diamond (h-BDD-1, 2.94 × 1021 atoms·cm−3; h-BDD-2, 9.10 × 1021 atoms·cm−3) films to investigate the effect of boron doping on the thermal stability of diamond films. A series of evidences, including air annealing experiments, thermogravimetric-differential scanning calorimetry (TG-DSC) analysis, and in-situ ultra-high-temperature confocal laser-scanning microscope (CLSM), demonstrated that the thermal stability of diamond films was obviously enhanced by boron doping. Consequently, the h-BDD-2 film exhibited the best thermal stability with an initial oxidation temperature above 900 °C, which was much higher than that of MCD film (709 °C). By deconvolving the X-ray photoelectron spectra, we believed that the transition of B–C bonds to stable oxy-boron carbide complexes (B 4 O–C, B 3 O–C) is the key to improving the thermal stability. These results not only reveal a new antioxidant mechanism of boron-doped diamond films but also pave a way for the application of diamond in high-temperature environments. [ABSTRACT FROM AUTHOR]

Singlet fission (SF), as an effective way to break through the Shockley–Queisser limit, can dramatically improve energy conversion efficiency in solar cell areas. The formation, separation, and relaxation of triplet-pair excitons directly affect the triplet yield, especially triplet-pair separation; thus, how to enhance the triplet-pair separation rate becomes one of the key points to improve SF efficiency; the decay mechanism where the singlet state is converted into two triplet states is significant for the study of the SF mechanism. Herein, we employ ultrafast transient absorption spectroscopy to study the singlet-fission process of nano-amorphous 6, 13-bis(triisopropylsilylethynyl)-Pentacene (TIPS-pentacene) films in a diamond anvil cell (DAC). A kinetics model related to the structural geometric details, as well as an evaluation of the pressure manipulation impacts, is demonstrated based on the experimental results. The results indicate that pressure manipulation enhanced the triplet-pair separation rates of SF-based materials according to their structural micro-environmental improvement when compressed in DAC, while the triplet-exciton transportation lifetime is prolonged. This work shows that pressure may effectively optimize the structural disorder of SF materials, which were found to improve triplet-pair separation efficiency and potentially offer an effective way to further improve SF efficiency. [ABSTRACT FROM AUTHOR]

Multilayer films of diamond‐like carbon (DLC) on monocrystalline diamond substrates have been for the first time obtained by plasma‐chemical deposition. Their chemical composition and structural and morphological properties are studied. The DLC individual layers differ in their sp3 carbon content. The multilayer nature of the resulting coatings is confirmed by periodic density modulation on the small‐angle X‐ray reflectometry curve and modulations in the CsC8, CsC6, CsC4 lines on the crater depth profile of secondary ions of elements (secondary ion mass spectrometry). The dependence of the deposition rate of multilayer DLC films on diamond, their composition and properties on the argon additive to the reaction gas mixture, as well as on methane flow, pressure and growth time, are studied. [ABSTRACT FROM AUTHOR]

We present a study of the structural features of polycrystalline a diamond film (PCDF) synthesized by the microwave plasma-enhanced chemical vapor deposition method from a hydrogen/pentane mixture and consider its photoelectric response to synchrotron radiation. Raman spectroscopy analysis of the PCDF cross-section revealed the presence of sp2-hybridized inclusions. As the distance from the PCDF growth surface increases, the amount of the non-diamond phase also increases, while its morphology changes from amorphous to crystalline graphite-like carbon. The investigation of the photoelectric response of PCDF was carried out at the "Cosmos" station using synchrotron radiation from the VEPP-4M storage ring. The PCDF detector exhibited maximum sensitivity at low bias voltage. This effect was attributed to the increased efficiency of collecting photo-induced charge carriers from the diamond to the sp2-hybridized inclusions followed by their subsequent transport through conductive paths along the boundaries between diamond crystallites. [ABSTRACT FROM AUTHOR]

This work shows considerable advance in combining the exceptional properties of chemical vapor deposition (CVD) diamond with the toughness of steel, a subject that has been sought since the early 1990s. Combining both the previously developed techniques for vanadium carbide (VC) deposition, namely laser cladding vanadium carbide (LCVC) and thermo-reactive deposition (TRD) in a salt bath, made it possible to achieve the deposition of a CVD diamond film on a D6 tool steel, with a very low stress level of 1.8 ± 0.1 GPa. This was the lowest value for growth at 750 °C substrate temperature. The LCVC step was a fast processing to thicken the VC layer, while the short-term TRD (only 1 hour) closed the cracks left in the LCVC coating, relieved the residual stresses resulting from the rapid solidification after the laser incidence, and promoted a phase transformation from V8C7 to V6C5, a phase with lower thermal expansion coefficient. Hot Filament Chemical Vapor Deposition (HFCVD) was used to perform the CVD diamond deposition. The vanadium carbide layer has been an intermediate layer capable of acting as an excellent diffusion barrier and able to satisfactorily mitigate the thermal stress of the CVD diamond. The samples were characterized by Scanning Electron Microscopy with Field Emission Gun (FEG-SEM) equipped with Energy-Dispersive X-ray Spectroscopy (EDS), X-ray diffractometry, Rockwell A (588.6 N) indentation tester. Raman spectroscopy was used to further characterize HFCVD diamond, to compute the thermal compressive stress. [ABSTRACT FROM AUTHOR]

In this study, three different substrate holder shapes—trapezoidal, circular frustum, and adjustable cyclic—were designed and optimized to enhance the quality of polycrystalline diamond films grown using microwave plasma chemical vapor deposition (MPCVD). Simulation results indicate that altering the shape of the substrate holder leads to a uniform distribution of the electric field on the surface, significantly suppressing the formation of secondary plasma. This design ensures a more even distribution of the temperature field and plasma environment on the substrate holder, resulting in a heart-shaped distribution. Polycrystalline diamond films were synthesized under these three different substrate holder conditions, and their morphology and crystal quality were characterized using optical microscopy, Raman spectroscopy, and high-resolution X-ray diffraction. Under conditions of 5 kW power and 90 Torr pressure, the adjustable cyclic substrate holder produced high-quality 3-inch diamond films with low stress and narrow Raman full width at half maximum (FWHM). The results confirm the reliability of the simulations and the effectiveness of the adjustable cyclic substrate holder. This approach provides a viable method for scaling up the size and improving the quality of polycrystalline diamond films for future applications. [ABSTRACT FROM AUTHOR]

Nucleation is important in processing of good quality diamond crystals and textured thin films by microwave plasma enhanced chemical vapor deposition (MPECVD) for applications in quantum devices and systems. Bias-enhanced nucleation (BEN) is one approach for diamond nucleation in situ during MPECVD. However, the mechanism of diamond nucleation by BEN is not well understood. This paper describes results on the nucleation of diamond within a carbon film upon application of electric field during the BEN-facilitated MPECVD process. The nature of the diamond film and nuclei formed is characterized by SEM (scanning electron microscopy), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). The HRTEM images and associated diffraction patterns of the nucleation layer show that the diamond nuclei are formed within the carbon film close to the Si (100) substrate surface under the influence of microwaves and electric fields that lead to formation of the textured diamond film and crystal upon further growth. These results are expected to develop diamond films of optimum quality containing a nitrogen-vacancy center for application in quantum systems. [ABSTRACT FROM AUTHOR]

The signature of the anisotropic superconducting order parameter (Δ) in heavily boron-doped nanocrystalline diamond (BNCD) films is demonstrated from the low-temperature resistivity and magnetoresistance measurements. Due to the presence of boron acceptors predominantly at the well-aligned grain boundaries, Rashba-type spin-orbit coupling can arise which influences the superconducting properties of these films. The one-dimensional (1D) filamentary channels of the grain boundaries suggest the modulation of the Δ which explains the peaks observed in the temperature-dependent resistance. This also explains the oscillatory magnetoresistance as a function of the magnetic fields and their angle dependence. From the observed superlattice-like microstructure of the BNCD films, a possible mechanism for creating Fulde–Ferrel and Larkin–Ovchinnikov (FFLO)-type state and chiral vortex lines from the superposition of multiple (Andreev) bound states is discussed. Overall, the interface states of the diamond films can be explained by the well-known Su-Schrieffer-Heeger “soliton” model which is supported by the observation of a zero-bias conductance peak. [ABSTRACT FROM AUTHOR]

This document is a special issue of the journal "Processes" focused on micro/nano manufacturing processes and optimization techniques. The articles in this issue cover a range of topics including the fabrication of micro/nano-structured surfaces, simulation and experimental investigation of laser manufacturing, and optimization techniques in microscale machining. The articles provide insights into various methods and technologies used in these areas and discuss their advantages, disadvantages, and potential applications. The authors also propose new approaches and techniques to address challenges and improve performance in micro/nano manufacturing processes. [Extracted from the article]

Y 2 O 3 /AlN composite films with different thicknesses of AlN interlayer were prepared on CVD diamond by RF magnetron sputtering. The influence of AlN thickness on the microstructure, adhesion strength, film stress, thermal shock resistance and infrared transmittance of the films was investigated by X-ray diffractometer, scanning electron microscopy, scanning probe microscopy, UV–Vis spectrophotometer, Fourier transform infrared spectrometer, scratch tester and 3-D optical surface profiler. The results show that CVD diamond coated with Y 2 O 3 /AlN composite films with different thicknesses of AlN have different degrees of anti-reflective effects in the 8–10 μm infrared band. The adhesion strength and quality of the composite film were improved with the AlN thickness increased, and the anti-reflective and anti-thermal shock of the film showed a trend of first increasing and then decreasing. CVD diamond coated with Y 2 O 3 /AlN composite films with 700 nm AlN interlayer has an average transmittance of 77 % in the 8–10 μm band and a good adhesion between interfaces. It can withstand rapid temperature changes and effectively protect the diamond substrate with little or no degradation of infrared optical properties. [ABSTRACT FROM AUTHOR]

Graphite-based metal transition-layer substrates hold great potential for preparing large-area diamond films and achieving crack-free release. In this study, a five-inch crack-free free-standing diamond film was prepared on a graphite substrate with a sacrificial Mo/Ti double-layer transition layer using direct-current arc plasma jet chemical vapor deposition (DC jet CVD). The interfacial bonding and diffusion behavior between the diamond and the transition layers were investigated. The effect of abundant metal particles and elemental diffusion between layers on film adhesion and stress release are discussed and analyzed. The surface of Ti layer prepared by the multi-arc ion-plating contains numerous metal particles that provide a template for the fine-crystalline Mo layer. Metal particles are encapsulated and embedded in the diamond and act as anchors that ensure the stability of the substrate–diamond bond during high-temperature deposition. After deposition, those metal particles act as weak points and play crucial stress-release roles. Mutual elemental diffusion occurs between the Ti, Mo, and diamond layers. Ti penetrates the Mo layer to form a continuous 140-nm-thick thin layer during the initial deposition period, facilitating diamond nucleation. Carbon from the plasma and diamond diffuses into the metal transition layer. Thermal stress generated between the diamond and the graphite substrate is released by destroying the metal transition layer with high thermal expansion coefficient and low elastic modulus during cooling from the deposition temperature. Cracks rapidly propagate along the interface between destroyable transition layers and graphite substrate, which results in the liftoff of a fully crack-free diamond film. [Display omitted] [ABSTRACT FROM AUTHOR]

Along with the increasing integration density and decreased feature size of current semiconductor technology, heterointegration of the Si‐based devices with diamond has acted as a promising strategy to relieve the existing heat dissipation problem. As one of the heterointegration methods, the microwave plasma chemical vapor deposition (MPCVD) method is utilized to synthesize large‐scale diamond films on a Si substrate, while distinct structures appear at the Si‐diamond interface. Investigation of the formation mechanisms and modulation strategies of the interface is crucial to optimize the heat dissipation behaviors. By taking advantage of electron microscopy, the formation of the epitaxial β‐SiC interlayer is found to be caused by the interaction between the anisotropically sputtered Si and the deposited amorphous carbon. Compared with the randomly oriented β‐SiC interlayer, larger diamond grain sizes can be obtained on the epitaxial β‐SiC interlayer under the same synthesis condition. Moreover, due to the competitive interfacial reactions, the epitaxial β‐SiC interlayer thickness can be reduced by increasing the CH4/H2 ratio (from 3% to 10%), while further increase in the ratio (to 20%) can lead to the broken of the epitaxial relationship. The above findings are expected to provide interfacial design strategies for multiple large‐scale diamond applications. [ABSTRACT FROM AUTHOR]

Nanocrystalline diamond (NCD) films are attractive for many applications due to their smooth surfaces while holding the properties of diamond. However, their growth rate is generally low using common Ar/CH4 with or without H2 chemistry and strongly dependent on the overall growth conditions using microwave plasma chemical vapor deposition (MPCVD). In this work, incorporating a small amount of N2 and O2 additives into CH4/H2 chemistry offered a much higher growth rate of NCD films, which is promising for some applications. Several novel series of experiments were designed and conducted to tailor the growth features of NCD films by fine-tuning of the gas-phase compositions with different amounts of nitrogen and oxygen addition into CH4/H2 gas mixtures. The influence of growth parameters, such as the absolute amount and their relative ratios of O2 and N2 additives; substrate temperature, which was adjusted by two ways and inferred by simulation; and microwave power on NCD formation, was investigated. Short and long deposition runs were carried out to study surface structural evolution with time under identical growth conditions. The morphology, crystalline and optical quality, orientation, and texture of the NCD samples were characterized and analyzed. A variety of NCD films of high average growth rates ranging from 2.1 μm/h up to 6.7 μm/h were successfully achieved by slightly adjusting the O2/CH4 amounts from 6.25% to 18.75%, while that of N2 was kept constant. The results clearly show that the beneficial use of fine-tuning of gas-phase compositions offers a simple and effective way to tailor the growth characteristics and physical properties of NCD films for optimizing the growth conditions to envisage some specific applications. [ABSTRACT FROM AUTHOR]

This study aims to optimize the performance of silicon nitride (Si3N4) ceramic bearings in high-temperature and heavy-duty environments and to address the issues of insufficient lubrication and heat generation in vacuum environments. To this end, we prepared diamond and MoS2-TiN composite films on silicon nitride ceramic substrates using a hot-wire chemical vapor deposition system and a physical vapor deposition system. The experimental results show that increasing the deposition time of the diamond films can significantly improve their hardness and elastic modulus, enhance the bonding of the films with the substrate, reduce the friction coefficient, and increase the thermal conductivity. Furthermore, by appropriately reducing the sputtering power of the MoS2 film, we can effectively minimize damage to the diamond film and further enhance the overall performance of the composite film. This study offers valuable insights for addressing lubrication and heat dissipation challenges in vacuum environments. [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]

We have developed an oxide reactive sputtering technique aiming at rapidly sputtering high-quality oxide films on a diamond surface, providing excellent thermal insulation in high-pressure and temperature experiments using a laser-heated diamond anvil cell (LH-DAC). We identified conditions for rapid deposition of an alumina layer on diamond anvils, showing deposition rates as high as 0.67 um/hr. We also investigated the deposition conditions of zirconia, which have lower thermal conductivity than alumina. Laser-heating tests were performed at high pressures and temperatures to evaluate the thermal insulation of the oxide film deposited on the diamond anvils. The heating efficiency of zirconia-deposited anvils was higher than that of the alumina-deposited ones. Our zirconia-sputtered anvils were capable of generating up to 2580 K at around megabar pressure without additional thermal insulation, demonstrating the potential of this technique for ultra-high temperature generation. [ABSTRACT FROM AUTHOR]

Maintaining the geometrical stability of hot filament is a challenge in chemical vapor deposition (CVD) over a larger area since deformation varies the distance between the filament and the substrate and, consequently, destroys the uniformity of diamond deposition. Herein, Ta filament is straightened with a tensile stress ranging from 4.40 to 11 MPa to suppress deformation, and the stability during the CVD process of diamond film is evaluated. Scanning electron microscopy and energy dispersive X‐ray are further utilized to investigate the morphological and structural evolutions of Ta filament. Results show that straightened Ta filament maintains geometrical stability without any visible deformation or breakage and uniform deposition of diamond film is obtained through Ta filament undergone a transformation from Ta to Ta2C and then to TaC. At high deposition pressure (7 kPa) or a low concentration of methane (1%), the straightened Ta filament goes through a moderate transformation, which implies the cracks caused by rough transformation can be avoided, thus prolonging the lifetime of straightened Ta filament. These works provide significant guidelines for the large‐scale manufacture of diamond deposition. [ABSTRACT FROM AUTHOR]

For high dielectric constant, conductive carbide ceramic fillers are scattered in polymer to fabricate composites. However, high conductivity of carbides will lead to high leakage conductance and dielectric loss. In this work, to balance dielectric properties, polymer/ZrC/diamond blends were prepared via complementation of fillers. To perform property comparison, polymer/ZrC blends were prepared. Crystal forms and micromorphology of fillers were confirmed. All blends were measured to obtain dielectric constant, dielectric loss and conductivity at various frequencies. Compared to polymer/ZrC blends, dielectric constant of ternary blends slightly decreases and dielectric loss sharply reduces. By analysing ternary blends, strong interaction at polymer/ZrC interface results in high dielectric constant and insulating diamond results in low-dielectric loss via greatly-decreased leakage conductance. Partner employment of ZrC and diamond is distinctive. Ternary blend loaded with 5 wt% ZrC and 3 wt% diamond exhibits well-balanced dielectric performances (dielectric constant ~ 35.3; dielectric loss ~ 0.48) at 100 Hz. This work will provide valid route for balancing dielectric properties of polymer/conductive carbide blends. [ABSTRACT FROM AUTHOR]

To further improve the manufacturing process and product performance of decorated bamboo filament board, the Box–Behnken response surface analysis method was used to analyze the correlation between the hot-pressing parameters and surface bonding strength, and the optimal process optimization parameters were obtained. In addition, the wettability and color of each group of samples were tested. The results show that the optimum process parameters of decorated bamboo filament boards were 130 °C, 165 s and 2.00 MPa, and the surface bonding strength was 1.58 MPa. The relative error between the measured value and the predicted value was less than 5%. The contact angle of the bamboo filament after hot pressing was higher than without hot pressing. However, there was no correlation between wettability and the hot-pressing parameters. There was no effect on the change in bamboo surface color. This indicates that the temperature range selected in this study meets the requirements of surface color control in production. [ABSTRACT FROM AUTHOR]

Modern integrated circuits (ICs) take advantage of three-dimensional (3D) nanostructures in devices and interconnects to achieve high-speed and ultra-low-power performance. The choice of electrical insulation materials with excellent dielectric strength, electrical resistivity, strong mechanical strength, and high thermal conductivity becomes critical. Diamond possesses these properties and is recently recognized as a promising dielectric material for the fabrication of advanced ICs, which are sensitive to detrimental high-temperature processes. Therefore, a high-rate low-temperature deposition technique for large-grain, high-quality diamond films of the thickness of a few tens to a few hundred nanometers is desirable. The diamond growth rate by microwave plasma chemical vapor deposition (MPCVD) decreases rapidly with lowering substrate temperature. In addition, the thermal conductivity of non-diamond carbon is much lower than that of diamond. Furthermore, a small-grain diamond film suffers from poor thermal conductivity due to frequent phonon scattering at grain boundaries. This paper reports a novel MPCVD process aiming at high growth rate, large grain size, and high sp3/sp2 ratio for diamond films deposited on silicon. Graphite paste containing nanoscale graphite and oxy-hydrocarbon binder and solvent vaporizes and mixes with gas feeds of hydrogen, methane, and carbon dioxide to form plasma. Rapid diamond growth of diamond seeds at 450 °C by the plasma results in large-grained diamond films on silicon at a high deposition rate of 200 nm/h. [ABSTRACT FROM AUTHOR]

The chemical vapor deposition (CVD) of diamond allows the controllable formation of the material with desirable structure and elemental composition. In this study, Ge-doped microcrystalline and nanocrystalline diamond (NCD) films are synthesized using microwave plasma-assisted CVD in CH4-H2-GeH4-N2 gas mixtures. We grow series of 2 μm thick NCD films with variations in gas composition [N2] = 0 − 4% and [CH4] = 10 − 15%. We investigate and compare the structure, phase composition, and luminescent characteristics of the grown films. The luminescent signals from Silicon vacancy (SiV, 738 nm) and Germanium vacancy (GeV, 602 nm) color centers in diamond are registered. The additional annealing of the as-grown films in air is used to remove the excessive sp2 phase that hinders their luminescent properties. For both SiV and GeV centers, we find conditions for CVD growth of NCD films that are as bright or even brighter than Si-doped and Ge-doped high-quality microcrystalline diamond films (MCD) grown without N2 additions. These results may be used for the fabrication of NCD films and plates with high concentrations of SiV and GeV centers, which may serve as source material for the fabrication of sub-micrometer-sized luminescent diamond particles for local optical thermometry. [ABSTRACT FROM AUTHOR]

A bottom-up method is described to grow patterned polycrystalline diamond on silicon substrates using polymer assisted seeding and photolithography. Diamond seeding densities were > 1011 cm−2. The pattern consists of well-defined features ranging from microns to millimeters in size. A systematic study was carried out to investigate the effects of CH4 concentration (1.5, 2.0, 2.5, and 3.0% in H2) on diamond grown using hot-filament chemical vapor deposition. The study is focused on the early growth regime following 30 min, 45 min, and 2 h process times. Scanning electron microscopy and atomic force microscopy measurements are used to study thickness, growth rate, grain size, grain morphology, and surface roughness of the polycrystalline diamond. SEM cross section images confirm the growth of high seeding diamond films without voids at the substrate interface. An increasing trend of lateral particles sizes, with increasing CH4, is observed reaching ~ 365 nm at the highest CH4 concentration. Material quality is checked using UV micro-Raman spectroscopy including line scans to investigate uniformity of patterned features. The results show that higher CH4 concentration leads to narrow linewidths and higher relative integrated intensities of diamond. These characteristics are consistent with improvements in the diamond quality in the early growth stages. [ABSTRACT FROM AUTHOR]

Optically active color centers in diamonds have been intensively studied due to their potential in photonics, energy harvesting, biosensing, and quantum computing. Silicon vacancy (SiV) center offers an advantage of suitable emission wavelength and narrow zero‐phonon line at room temperature. Measurement of surface potential and photovoltage can provide better understanding of the physics and control of SiV light emission, such as charge states and charging effects. Herein, optoelectronic properties of nanocrystalline diamond films with SiV centers at different layer thicknesses (10–200 nm, controlled by the growth time) under ambient conditions are studied. Time‐dependent measurements are performed in the light–dark–light cycle. Positive photovoltage arises on samples with SiV layer thicknesses below 55 nm on both H‐ and O‐terminated surfaces. Above 55 nm the photovoltage switches to negative. This layer thickness thus represents a halfway boundary between surface‐controllable and bulk SiV centers dominant contribution. A band diagram scheme explaining the photovoltage switching mechanism is provided. [ABSTRACT FROM AUTHOR]

Diamonds produced using chemical vapor deposition (CVD) have found many applications in various fields of science and technology. Many applications involve polycrystalline CVD diamond films of micron thicknesses. However, a variety of optical, thermal, mechanical, and radiation sensing applications require more bulky CVD diamond samples. We report the results of a magnetic resonance and structural study of a thick, sizable polycrystalline CVD diamond disc, both as-prepared and treated with e-beam irradiation/high-temperature annealing, as well as gamma irradiation. The combination of various magnetic resonance techniques reveals and enables the attribution of a plentiful collection of paramagnetic defects of doublet and triplet spin origin. Analysis of spectra, electron, and nuclear spin relaxation, as well as nuclear spin diffusion, supports the conclusion of significant macro- and micro-inhomogeneities in the distribution of nitrogen-related defects. [ABSTRACT FROM AUTHOR]

High radiation resistance, chemical inertness, the ability to operate at elevated temperatures, high mobility and efficiency of charge-carrier collection are important properties of diamond for designing detectors and spectrometers of ionizing radiation. Currently, diagnostics of neutrons and neutral particle fluxes based on diamond detectors for the ITER thermonuclear reactor are justified and developed. This work presents the results of a Raman spectroscopy and photoluminescence spectroscopy study of the electronic quality of synthesized epitaxial diamond films obtained by vapor deposition in a hydrogen and methane mixture in the ARDIS reactor on boron-doped single-crystal diamond substrates. To confirm their electronic quality, detectors have been made from films selected by spectrometric methods and the charge collection efficiency and energy resolution have been measured when irradiated with alpha particles from a 241Am source and 14.7 MeV fast neutrons from the ING-07T2 neutron generator. [ABSTRACT FROM AUTHOR]

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]

Creating dense and shallow nitrogen-vacancy (NV) ensembles with good spin properties is a prerequisite for developing diamond-based quantum sensors exhibiting better performance. Ion implantation is a key enabling tool for precisely controlling spatial localization and density of NV color centers in diamond. However, it suffers from a low creation yield, while higher ion fluences significantly damage the crystal lattice. In this work, we realize N2+ ion implantation in the 30–40 keV range at high temperatures. At 800 °C, NV's ensemble photoluminescence emission is three to four times higher than room temperature implanted films, while narrow electron spin resonance linewidths of 1.5 MHz, comparable to well-established implantation techniques, are obtained. In addition, we found that ion fluences above 2 × 1014 ions/cm2 can be used without graphitization of the diamond film, in contrast to room temperature implantation. This study opens promising perspectives in optimizing diamond films with implanted NV ensembles that could be integrated into quantum sensing devices. [ABSTRACT FROM AUTHOR]

We present site-coincident imaging of a high dislocation density boron-doped chemical vapor deposition-grown homoepitaxial (001) diamond film using electron channeling contrast imaging (ECCI), cathodoluminescence, transmission electron microscopy (TEM), and scanning secondary ion mass spectroscopy (SIMS). With growing interest in large area heteroepitaxial substrates, we show that ECCI is a promising technique to accurately evaluate dislocations in diamond films. We find the electron backscatter yield is sufficient to distinguish individual threading dislocations in ECCI despite the low atomic number of carbon, and we have generally good agreement between dislocations observed in ECCI and TEM of the same region. Importantly, relying on luminescence in the 430 nm dislocation-related A-band alone results in an underestimation of the defect density as we find only 20%–40% of the threading dislocations luminesce. We further show that dislocations do not perturb the spatial uniformity of boron doping measured by SIMS, even when the dislocations are clustered with high density, and we can tentatively rule out strong segregation effects at the dislocations. Our results establish the complementary use of microscopy and microanalysis methods to rapidly characterize and understand the impact of dislocations in diamond thin films. [ABSTRACT FROM AUTHOR]

Chemical vapor deposition produced diamonds attract considerable scientific and industrial interest due to their exceptional mechanical and functional properties. Here, hot filament (HF) chemical vapor deposition was used to synthesize two diamond thin films with different cross-sectional microstructure and residual stresses. Structural characterization by scanning electron microscopy, Raman spectroscopy, and cross-sectional synchrotron x-ray nanodiffraction revealed different diamond morphologies. While the microcrystalline diamond film exhibits pronounced microstructural gradients expressed by gradually increasing (i) intensities of the 111 Debye-Scherrer rings, (ii) ⟨ 110 ⟩ fiber texture sharpness, (iii) grain size, and (iv) slightly oscillating residual stress at the level of −0.5 GPa, the nanocrystalline diamond film showed no pronounced cross-sectional variation of microstructure above the nucleation zone of ∼0.5 μm and a steady stress level of 0.25 GPa. In situ micromechanical cantilever bending tests revealed highly different mechanical properties of the two films. In detail, Young's modulus of 830 ± 53 and 459 ± 53 GPa, fracture stress of 12.4 ± 0.8 and 7.8 ± 1.0 GPa, and fracture toughness values of 6.9 ± 0.4 and 3.6 ± 0.3 MPa⋅m½ were evaluated for the micro- and nanocrystalline diamond films, respectively. In summary, this study provides valuable insights into the microstructure-residual stress correlation in micro- and nanocrystalline diamond films, especially illuminating their influence on micromechanical properties. [ABSTRACT FROM AUTHOR]