High-performance Diamond Research Articles

STUDY ON THE PROPERTIES OF DIAMOND FILMS ON CEMENTED CARBIDE SUBSTRATES BY SURFACE IMPLANTATION PRETREATMENT PROCESS

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 [Formula: see text]m, 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.

Unusual electrochemical properties of boron and silicon Co-doped diamond electrodes

Boron-doped diamond (BDD) films exhibit exceptional physicochemical properties and have been utilized in numerous fields. As a common impurity in diamond, silicon is inevitably introduced into the diamond lattice during certain growth process. However, there are limited reports on the impact of silicon co-doping on the electrochemical properties of BDD electrodes. In this paper, we prepared a series of BDD electrodes with various silicon contents and made a systematic evaluation of these electrodes in terms of physicochemical properties. The results indicated that silicon and boron co-doped diamond (SiBDD) electrodes displayed a broader potential window and lower background current compared to the pure BDD electrode. Additionally, we observed that the electron transfer rate of the electrodes in the inner ([Fe(CN)6]3−/4−) redox systems exhibited a rising trend with increasing silicon content, whereas the electron transfer rate of the outer ([Ru(NH3)6]3+/2+) redox systems displayed contrasting trend. Surface analyses and electrochemical measurements results suggested that the unusual phenomena might stem from the alterations in surface functional groups and carrier density of the electrode inducing by silicon co-doping. In general, our results demonstrate, for the first time, that Si co-doping can influence the surface functional groups and carrier behavior of BDD electrodes, thereby altering the electrode's electrochemical performance. This provides new insights for the design of high-performance diamond electrodes.

Effects of Ni–Cr–Mo–Si–B prealloy additives on the properties of Fe-based diamond composites

In this study, Fe-based diamond composites with various Ni–Cr–Mo–Si–B prealloy additives were prepared using hot-press sintering, and the effects of the Ni–Cr–Mo–Si–B content on the relative density, bending strength, Rockwell hardness, and frictional wear properties of the Fe–Cu–Co–Sn matrix were investigated. Additionally, the effect of the composition of the Ni–Cr–Mo–Si–B additives on the interface between the matrix and diamond was studied. The Ni and Cr in the additives facilitated a tight bonding interface without notable gaps between the diamond and Fe–Cu–Co–Sn matrix. Considering the overall performance of the materials, the optimal addition of Ni–Cr–Mo–Si–B was determined to be 10 %, which resulted in notably improved comprehensive performance indicators of the Fe-based diamond composite materials. For example, diamond drill bits made with this formulation exhibited a wear ratio of 1600 mm/g and a penetration rate of 29.21 mm/min, representing increases of 29 % and 44.96 %, respectively, compared to those of drill bits without Ni–Cr–Mo–Si–B additives. Developing high-performance diamond drill bits with increased ROP and extended service lives to enhanced performance, efficiency, and cost-effectiveness in drilling operations across different industries, ranging from mining and construction to oil and gas exploration.

Novel approach to produce 3D boron-doped diamond for pollutant removal from water

Diamond growth from Chemical Vapor Deposition (CVD) on foreign substrates can require different pretreatment not only to improve the film nucleation but also to assure its adhesion by decreasing the expected film/substrate interface stress. To improve boron-doped film nucleation, growth, and adherence, different substrate pretreatments have been used mainly from the seeding process with diamond powder at various particle sizes. Despite this, the development of diamond growth on a Ti mesh remains difficult because of the requirement of a cohesive film to cover a 3D macroporous sample with varying growth rates based on its distinct network geometry. Then, this work describes a novel approach to growing boron-doped diamond (BDD) and boron-doped ultrananocrystalline diamond (B-UNCD) on titanium dioxide nanotubes (TDNT) produced simultaneously on both sides of Ti mesh by an anodization process. The films were obtained from two-step growth processes by assuring the entire diamond overlay on both TDNT/Ti mesh sides, including their outer/inner surfaces, as a 3D sample. TiO2 - TiC conversion has dominated the renucleation process, facilitating the nanometric scale control. The film morphologies were systematically analyzed by FEG-SEM images at different sample planes and depths for both sample sides at different stages of film growth. The unique morphology of titania nanotubes associated with columnar and/or renucleation development of BDD, considering the film defects and valley, can systematically increase the electrode specific area. Raman spectra showed the film quality and its micro and/or ultrananodiamond structure and the boron doping features. Also, this growth process allowed a dopant-controlled adjustable conductivity. Then, the boron doping levels for both films were evaluated from Mott-Schottky plots at around 1019 Bcm−3, characterizing them with good conductivity. In addition, electrochemical measurements from Cyclic Voltammetry (CV) confirmed the expected diamond response on redox pair following the quasi-reversible criteria as high-performance diamond electrodes and in situ Raman spectroelectrochemical measurements assessed the stability of samples during electrochemical measurements, ensuring structural integrity. Finally, the samples were applied to the degradation of methylene blue, proving to be superior materials for electrochemical applications due to their advantages compared to those of similar 2D electrodes.

Efficient manufacture of high-performance electroplated diamond wires utilizing Cr-coated diamond micro-powder

The slicing of silicon ingots using electroplated diamond wires is a fundamental process in the creation of semiconductor devices such as chips and photovoltaic cells. Composite electroplating, a process that uses nickel (Ni) plating to fix diamond particles onto a steel wire, is a critical step in the manufacturing of these diamond wires. In this work, chromium (Cr)-coated diamond was used to achieve rapid and high-quality composite electroplating, thereby aiding the production of high-performance diamond wire saws. The Cr-coated diamond micro-powder was prepared utilizing vacuum slow evaporation technology at a temperature of 850 °C. This resulted in a uniform and firm Cr coating that was firmly bonded to the diamond surface via Cr3C2. Subsequent electrochemical tests were conducted in the composite electroplating bath. Linear scanning voltammetric curves revealed that the Cr-coated diamond was capable of inducing a more positive shift in the overpotential of Ni deposition, thus enhancing the reaction beyond that of uncoated diamond micro-powder. Additionally, the electrochemical impedance spectra indicated a decrease in charge transfer resistance during composite electroplating, attributable to the conductivity of the Cr-coated diamond. Electroplated diamond wires incorporating Cr-coated diamond demonstrated a greater abrasive density per unit length. SEM results showed that Ni was able to deposit on the Cr-coated diamond surface, resulting in the abrasives being completely covered by the Ni plating. The Cr-coated diamond wire exhibits a stronger resistance to abrasive detachment after cutting, which could increase the diamond-protrusion of the wire. The utilization of Cr-coated diamond micro-powder as an abrasive is anticipated to enhance the manufacturing efficiency of diamond wires and improve product quality, thereby promoting advancements in hard and brittle material processing technology.

First-principles comparative study on diamond/carbide combinations: Interfacial adhesion and bonding nature

Joining diamond and metal is vital to expand their application scope in electronic and military industries. A metallic carbide layer will be inevitably introduced on diamond to ensure strength and wettability, its tight interfacial adhesion with diamond needs to be satisfied in priority. Here, the bonding characteristics of diamond(001)/carbide(001) interfaces were comparatively studied through first-principles calculations, wherein six experimentally possible carbides MxCy (TiC, Cr3C2, V8C7, Mo2C, ZrC, and WC) were employed. By evaluating the thermal stability, activity, and mechanical properties of bulk MxCy, as well as the corresponding interface energy and adhesion work, three outstanding interface structures (with Cr, W, and Ti) were yielded. Further analysis of electronic structures showed the interfacial bonding originated from M–C bonds and stronger CC covalent bonds. Besides, bonding strength was found to be significantly related to interfacial charge density and orbital hybridization. Overall, Cr might be the preferable carbide former with high interfacial stability and strength. This study provided atomic insights into the tailoring of diamond/carbide combination with superior interfacial compatibility to develop high-performance diamond devices.

Technological Principles of Complex Plasma-Beam Surface Treatment of Al2O3/TiC and SiAlON Ceramics

Thermomechanical action during high-performance diamond grinding of sintered cutting Al2O3/TiC and SiAlON ceramics leads to increased defectiveness of the surface layer of the deposited TiZrN and CrAlSiN/DLC coatings. It predetermines the discontinuous and porous coatings and reduces its effectiveness under abrasive exposure and fretting wear. The developed technological approach is based on “dry” etching with beams of accelerated argon atoms with an energy of 5 keV for high-performance removal of defects. It ensures the removal of the defective layer on ceramics and reduces the index of defectiveness (the product of defects’ density per unit surface area) by several orders of magnitude, compared with diamond grinding. There are no pronounced discontinuities and pores in the microstructure of coatings. Under mechanical loads, the coatings ensure a stable boundary anti-friction film between the ceramics and counter body that significantly increases the wear resistance of samples. The treatment reduces the volumetric wear under 20 min of abrasive action by 2 and 6 times for TiZrN and CrAlSiN/DLC coatings for Al2O3/TiC and by 5 and 23 times for SiAlON. The volumetric wear under fretting wear at 105 friction cycles is reduced by 2–3 times for both coatings for Al2O3/TiC and by 3–4 times for SiAlON.

Adhesive and tensile properties of diamond(001)/TiC(111) interfaces: A first-principles investigation

Since a nanometer-thick carbide layer will be indispensably produced on diamond to ensure wettability with metallic parts, the interfacial properties of diamond/carbide directly affect the service performance of diamond devices. Herein, first-principles calculations were performed to investigate the interfacial properties and tensile responses of diamond(001)/TiC(111) interfaces. Taking into account Ti- and C-termination of TiC(111), and interfacial stacking of hollow- and top-site, four interface models were established. The results showed that Ti-termination could only be stacked by hollow-site. The analysis of energy and electronic structure suggested that hollow-site or C-termination favored to produce a more stable interface, attributing to stronger interfacial C-C covalent bonds and even the additional ionic attraction from Ti atoms, which enhanced the bonding strength significantly. Furthermore, the tensile simulations indicated cleavage always ignited from Ti-C bonds, of which along the interface for Ti-termination and within the TiC for C-termination. Growing C-terminated TiC could greatly improve interfacial stability, but at the expense of mechanical strength. This owed to the homogenization of C-termination by diamond surface. The results provided an atomic insight to characterize the structure and bonding of diamond/TiC interfaces, laying the foundation for developing high-performance diamond devices.

High breakdown electric field diamond Schottky barrier diode with HfO2 field plate

In this work, we fabricated a vertical diamond Schottky barrier diode (SBD) with a high breakdown electric field of 4.8 MV/cm and a forward current density of 2361 A/cm2. Compared with a regular diamond SBD, the breakdown electric field of SBD with a HfO2 field plate (FP) increased from 183 to 302 V, the current swing (ION/IOFF) was on the order of 1011. As the thickness of the HfO2 FP increased from 200 to 400 nm, the breakdown voltage of the SBD increased from 280 to 314 V, and the corresponding breakdown electric field increased from 4.5 to 5 MV/cm. We also measured the current–voltage characteristics at different temperatures to investigate the cause of the high on-resistance. As the measured temperature increased from 25 to 150 °C, the on-resistance of the device decreased from 4.7 to 1.7 mΩ·cm2. By studying the interface between HfO2 and the diamond, we found that HfO2 can reduce the interface state density of the Schottky contact. The interface state density of Zr/HfO2/diamond was lower than 1.5 × 1013 eV−1·cm−2. This work provides a simple strategy for realizing high-performance diamond SBDs.

High-Performance Diamond Phototransistor with Gate Controllable Gain and Speed.

This paper presents a fabricated solar-blind phototransistor based on hydrogen-terminated diamond. The phototransistor shows a large photocurrent and enhancement of responsivity over conventional two-terminal diamond-based photodetector. These enhancement effects are owing to the internal gain of the phototransistor. The fabricated phototransistor exhibits a high photoresponsivity (R) of 2.16 × 104 A/W and a detectivity (D*) of 9.63 × 1011 jones, with gate voltage (VG) and drain voltage of approximately -1.5 V and -5 V, respectively, under 213 nm light illumination. Even at ultralow operating voltage of -0.01 V, the device records satisfactory performance with R and D* of 146.7 A/W and 6.19 × 1010 jones, respectively. By adjusting the VG, photocurrent generation in the device can be continuously tuned from the fast photoconductive effect to the optical gating effect with high optical gain. When VG increases from 1.4 to 2.4 V, the decay time decreases from 1512.0 to 25.5 ms. Therefore, responsivity, dark current, Iphoto/Idark, and decay time of the device can be well tuned by VG.

Inhomogeneous heterojunction performance of Zr/diamond Schottky diode with Gaussian distribution of barrier heights for high sensitivity temperature sensor

Herein, we demonstrated the fabrication and operation of vertical diamond Schottky barrier diode (SBD) as a high-performance temperature sensor. The current transport mechanism and temperature sensor properties of Zr/p-diamond SBD were comprehensively investigated with operating temperatures up to 448 K. At room temperature, Zr/p-diamond SBD exhibits outstanding performances with a high rectification ratio of 2.28 × 1010, a low specific on-resistance of 0.5 mΩ•cm2, a large Schottky barrier height (SBH) of 1.43 eV, a low ideality factor of 1.77, and an extremely low saturation current of 4.42 × 10−22 A. The enhanced-performance with a higher forward current and a lower reverse leakage current is observed to be across a wide temperature range from 323 to 448 K. Additionally, a significant improvement of rectifying current curve with a highest rectification ratio over 1012 is obtained at 423 K. The SBH increases whereas the ideality factor decreases with temperature increasing, indicating barrier inhomogeneities at Zr/p-diamond interface. The temperature-dependent electrical transport characteristics on spatially inhomogeneous Schottky contacts can be successfully described by potential fluctuations model. The extracted original value of Richardson constant (A*) is 0.0153 A/cm2•K2, which is much lesser than theoretical value of 96 A/cm2•K2. The discrepancy of A* value from theoretical value has been well explained by thermionic emission model with Gaussian distribution of barrier inhomogeneity. The values of mean SBH and A* extracted from modified Richardson plot depending on SBH inhomogeneity are 1.76 eV and 105.51 A/cm2•K2, respectively. With a Gaussian distribution take into account, the A* value is close to the theoretical value, and confirmed the existence of SBH inhomogeneity at Zr/p-diamond interface. Furthermore, for Zr/p-diamond SBD operating as a temperature sensor, the voltage drop across the diode decreases linearly with increasing temperature at a specific forward current level, contributing to a highest sensor sensitivity of 6.8 mV/K. The reported results in this work are among the best to date in diamond SBD temperature sensor. Although not optimized for temperature sensor, the high and thermally stable rectifying barriers make Zr/p-diamond SBD a strong candidates for high-performance diamond rectifying diode and temperature sensor.

Self-aligned patterning technique for fabricating high-performance diamond sensor arrays with nanoscale precision.

Efficient, nanoscale precision alignment of defect center creation in photonics structures in challenges the realization of high-performance photonic devices and quantum technology applications. Here, we propose a facile self-aligned patterning technique based on conventional engineering technology, with doping precision that can reach ~15 nm. We demonstrate this technique by fabricating diamond nanopillar sensor arrays with high consistency and near-optimal photon counts. The sensor array achieves high yield approaching the theoretical limit, and high efficiency for filtering sensors with different numbers of nitrogen vacancy centers. Combined with appropriate crystal orientation, the system achieves a saturated fluorescence rate of 4.34 Mcps and effective fluorescence-dependent detection sensitivity of 1800 cps−1/2 . These sensors also show enhanced spin properties in the isotope-enriched diamond. Our technique is applicable to all similar solid-state systems and could facilitate the development of parallel quantum sensing and scalable information processing.

High performance diamond-based solar-blind photodetectors enabled by Schottky barrier modulation

Diamond, which possesses an ultra-wide bandgap, high thermal conductivity, and super thermal and chemical stability, is a promising material for deep-ultraviolet optoelectronics. However, it is still difficult for diamond photodetectors to meet the requirements of practical applications due to their relatively low responsivity. Here, we demonstrate a high-performance diamond photodetector realized via Schottky barrier modulation. Defect states and hydrogen terminals are introduced onto the surface of the diamond by hydrogen plasma treatment. Under illumination, photon-generated electrons are trapped by the defect states at the surface of the diamond, which lowers dramatically the Schottky barrier height, leading to high photocurrent of the photodetector. As a result, our device exhibits a responsivity of 524.9 A/W, a gain of 2958, and a detectivity of 3.42 × 1015 cm Hz1/2 W−1, all of which are among the highest values ever reported for diamond-based photodetectors. Thus, our results suggest a novel strategy for design and fabrication of high-performance diamond photodetectors.

Energy absorption of metal-composite hybrid tubes with a diamond origami pattern

The metal origami tubes which are employed as energy absorption devices have been widely studied. Because the tubes can deform in a high-performance diamond mode (DM) with lots of creases turning into the traveling plastic hinge lines under axial crushing. However, for the composite origami tube, several large fragments rather than the traveling plastic hinge lines were observed in the axial crushing experiments, which means that the origami pattern cannot trigger the DM. Therefore, in this research, the metal origami tube is introduced on the outside of the composite origami tube, forcing the composite origami tube to deform with the deformation of the metal tube (i.e., the DM). Hence more traveling hinge lines are generated resulting in more fiber and matrix damage, which can effectively improve the energy absorption. The experimental results show that the energy absorption of the composite tube can be greatly improved by about 58.64% in the hybrid tube, compared to the single composite tube. In addition, the parameter studies of the hybrid origami tube indicate that it can deform in the DM in a wide range of geometric parameters.

EFFECT OF MECHANICAL AND TRIBOLOGICAL PROPERTIES OF DIAMOND FILMS ON VARIOUS SUBSTRATES

Geological drilling required high-performance diamond drill bits. In this paper, diamond films were deposited on different drill bit substrates based on the MPCVD equipment. The properties of diamond films were analyzed by scanning electron microscopy (SEM), Raman spectra, X-ray diffraction (XRD) and tribological tests. The results showed that surface morphology of the four different substrates was good and the grain size was uniform. The diamond drill bit substrates include polycrystalline diamond compact (PDC), cemented carbide (WC–Co), impregnated diamond (IPD) and diamond thick-film welded (DT) sheets. The coefficients of friction of the deposited protective films are 0.15, 0.25, 0.23 and 0.29, respectively. What is more, the wear rates of protective films are [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text][Formula: see text]mm3/N[Formula: see text]m, respectively. Addition of diamond films could effectively reduce the friction coefficient on the surface and improve the service life of drill bit.

Hydrogen-Terminated Diamond MOSFETs Using Ultrathin Glassy Ga2O3 Dielectric Formed by Low-Temperature Liquid Metal Printing Method

The p-type surface conductivity of hydrogen-terminated diamond (H-diamond) provides a viable approach toward diamond-based wide-bandgap metal-oxide-semiconductor field-effect transistors (MOSFETs) for high-power and high-frequency electronics. A facile, low-cost, and low-temperature method to form gate dielectrics on diamond that also preserves the integrity of hydrogen-termination is highly desirable for high-performance diamond surface electronics with process flexibility and high yield. In this work, we demonstrate a p-channel diamond MOSFET with an ultrathin glassy Ga2O3 dielectric layer derived from liquid metal. A liquid metal printing method was employed to transfer an amorphous Ga2O3 layer over the desired active p-channel region of H-diamond at low temperature, allowing the protection and preservation the hydrogen-terminated surface while also forming an efficient gate dielectric. The results of this work suggest that the liquid metal method can provide an efficient, low-cost, and high-yield pathway to form high-quality dielectrics for diamond-based transistors.

Diamond inverter consisted of high mobility and low on-resistance enhancement-mode C[sbnd]H diamond MISFET

Hydrogenated diamond (CH diamond) inverters have been fabricated by normally-off Al/BaF2/C-H diamond metal-insulator-semiconductor field effect transistors (MISFETs) and load resistors. Electron beam evaporation was used to deposit BaF2 film on the diamond surface at room temperature to reduce thermal degradation effect on the CH bond and adsorbates during the deposition. The resulting 4-μm normally-off MISFET achieves the maximum saturation drain current, on-resistance, maximum transconductance and switching ratio of −113.4 mA/mm, 37.1 Ω·mm, 35.4 mS/mm and 108, respectively. Effective hole mobility of more than 200 cm2/V·s is achieved in a large gate voltage range (−0.35 V ≤ VGS -VTH ≤ −4.35 V). Correspondingly, based on the high-performance diamond MISFET, the diamond inverters exhibit good voltage transfer characteristics and dynamic switching characteristics at the frequency of 50 kHz.

Diamond MOSFET with MoO3/Si3N4 doubly stacked gate dielectric

A hydrogen terminated diamond MOSFET with MoO3/Si3N4 doubly stacked gate dielectrics was fabricated on a single crystalline diamond sample. Compared to a device with single MoO3 layer gate dielectrics, the device performance was improved due to the improvement in the gate voltage, which benefited from the doubly stacked gate dielectric. The device with 4 μm gate length shows a maximum output current of 118.67 mA/mm and an ultra-low resistance of 36.15 Ω mm at the gate voltage of −5 V. In addition, the device shows a maximum transconductance of 35 mS/mm. These results indicate that the dielectric with high work function has high potential to achieve a high-performance diamond MOSFET.

Charge stability of shallow single nitrogen-vacancy centers in lightly boron-doped diamond

Nitrogen vacancy (NV) centers in diamond must be in a stable negatively charged state for their application to quantum sensing and quantum information processing. In this study, we investigated the charge-state stability of single NV centers in lightly boron-doped diamond ([B] ≈ 1 × 1015 cm−3). Photoluminescence and optically detected magnetic resonance measurements indicated that single NV centers near the diamond surface are negatively charged despite the presence of boron acceptors. This unique phenomenon can be explained by charge transfer between the NV centers and their local environment under laser excitation. This study provides a new perspective on the charge stability of single NV centers in lightly doped diamond and insights for further development of high-performance diamond quantum devices.

Phase-field modeling of selective laser brazing of diamond grits

Diamond grit is widely used in cutting, grinding, and polishing tools for its superior mechanical properties and performance in machining hard materials. Selective laser brazing (SLB) of diamond grits is a new additive manufacturing technique that has great potential to fabricate the next generation of high-performance diamond tools. However, fundamental understanding and quantitative analysis for the design and tuning of the SLB process and the resulting bonding efficiency are not yet established as the process is complicated by heating, fusion, wetting, solidification, grit migration, bonding, reaction, and the interplay between these effects. We present a thermodynamically consistent phase-field theoretical model for the prediction of melting and wetting of SLB on diamond grits using a powder-based additive manufacturing technique. The melting dynamics is driven by laser heating in a chamber filled with argon gas and is coupled with the motion of multiple three-phase contact lines. The relevant wetting dynamics, interfacial morphology, and temperature distribution are computationally resolved in a simplified two-dimensional (2D) configuration.