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This article reviews the state of the art in inversion-type p-channel diamond MOSFETs. We successfully developed the world’s first inversion-channel homoepitaxial and heteroepitaxial diamond MOSFETs. We investigated the dependence of phosphorus concentration (NP) of the n-type body on field-effect mobility (μFE) and interface state density (Dit) for the inversion channel homoepitaxial diamond MOSFETs. With regard to the electrical properties of both the homoepitaxial and heteroepitaxial diamond MOSFETs, they suffer from low μFE and one main reason is high Dit. To improve the interface quality, we proposed a novel technique to form OH-termination by using H-diamond followed by wet annealing, instead of the previous OH-termination formed on O-diamond. We made precise interface characterization for diamond MOS capacitors by using the high-low C–V method and the conductance method, providing further insights into the trap properties at Al2O3/diamond interface, which would be beneficial for performance enhancement of the inversion-type p-channel diamond MOSFETs. Graphic abstract

We successfully fabricated the inversion-type p-channel metal–oxide–semiconductor field-effect transistor (MOSFET) on heteroepitaxially grown free-standing diamond using silicon-based substrates. The drain current–drain voltage (Ids–Vds) and drain current–gate voltage (Ids–Vgs) characteristics were examined. The maximum drain current density and the peak field effect mobility (μFE) were around 0.35 mA/mm and 2.7 cm2 V−1s−1, which were lower than our reported results of the homoepitaxial diamond MOSFETs fabricated on high-pressure, high-temperature (HPHT) substrates. The interface state density (Dit) extracted from the subthreshold region was around 5.5 × 1012 cm−2eV−1, comparable to our reported results of the homoepitaxial diamond MOSFET. To further examine the reason for the low μFE, atomic force microscopy (AFM) measurements were performed for the n-type body of the heteroepitaxial diamond MOSFET, and we found that the surface roughness was much larger than our reported ones of the homoepitaxial diamond MOSFET. It can be deduced that the surface roughness would be one main limiting factor for the field effect mobility of the heteroepitaxial diamond MOSFET. The imperfect diamond heteroepitaxy would also degrade the field effect mobility. This work explores the potential of the inversion-type p-channel heteroepitaxial diamond MOSFETs, which would facilitate the practical application of diamond power devices.

Microwave pulse sequences are the basis of coherent manipulation of the electronic spin ground state in nitrogen vacancy (NV) centers. In this work we demonstrate stimulated Raman transitions (SRTs) and stimulated Raman adiabatic passage (STIRAP), two ways to drive the dipole-forbidden transition between two spin sublevels in the electronic triplet ground state of the NV center. This driving is achieved by a two-photon Raman microwave pulse which simultaneously drives two detuned transitions via a virtual level for SRTs or via two adiabatic and partially overlapping resonant microwave pulses for STIRAP. We lay the theoretical framework of SRT and STIRAP dynamics and verify experimentally the theoretical predictions of population inversion by observing the dipole-forbidden transition in the ground state of a single NV center. A comparison of the two schemes showed better robustness and success of the spin swap for STIRAP compared to SRT.

Diamond coatings are characterised by outstanding mechanical and chemical robustness and hence, thin diamond layers doped with boron are particularly interesting for transparent electrodes, e.g., for spectroelectrochemical applications. In this study, we present a non-destructive chemometric method to determine thickness and boron concentration of as-deposited heavily doped diamond films on silicon substrates, which may be used, e.g., as electroactive infrared transparent windows. Using partial least-squares regression, we readily predicted these parameters with high accuracy from Raman spectra after calibration with a set of diamond films, previously characterised by secondary ion mass spectrometry. Due to the Fano resonance caused by the boron incorporation into the diamond lattice, which is observable in the Raman spectrum, a precise determination of the boron concentration is possible. In addition, for diamond films below the wavelength of the used Raman laser, we were able to determine the thickness of the as-grown films and gain information on the underlying substrate.

International audience; Herein, a technological process for the fabrication of n-type doped V-shaped structures on (100) single-crystalline diamond substrates, designed to overcome the limitations of n-type doping on (100) surfaces, is presented. This doping enhancement process can be applied to realize electronic power devices such as a junction barrier Schottky diode or junction field effect transistors with low on-resistance. Herein, a catalytic etching process is performed by using square-shaped nickel masks on the diamond surface and annealing in a hydrogen atmosphere, resulting in the formation of inverted pyramidal structures with flat {111} sidewalls. The resulting V-shaped structures are subsequently overgrown with phosphorus-doped diamond to achieve n-type doped facets with higher doping concentrations. Cathodoluminescence studies reveal the predominant incorporation of phosphorus donors on the {111} sidewalls of V-shaped structures.

Vertical diamond Schottky diodes with blocking voltages $V_{\text{BD}} > 2.4 \text{ kV}$ and on-resistances $R_{\text{On}} < 400 \text{ m}��\text{cm}^{2}$ were fabricated on homoepitaxially grown diamond layers with different surface morphologies. The morphology (smooth as-grown, hillock-rich, polished) influences the Schottky barrier, the carrier transport properties, and consequently the device performance. The smooth as-grown sample exhibited a low reverse current density $J_{\text{Rev}} < 10^{-4} \text{ A}/\text{cm}^{2}$ for reverse voltages up to $2.2 \text{ kV}$. The hillock-rich sample blocked similar voltages with a slight increase in the reverse current density ($J_{\text{Rev}} < 10^{-3} \text{ A}/\text{cm}^{2}$). The calculated 1D-breakdown field, however, was reduced by $30 \text{ } \%$, indicating a field enhancement induced by the inhomogeneous surface. The polished sample demonstrated a similar breakdown voltage and reverse current density as the smooth as-grown sample, suggesting that a polished surface can be suitable for device fabrication. However, a statistical analysis of several diodes of each sample showed the importance of the substrate quality: A high density of defects both reduces the feasible device area and increases the reverse current density. In forward direction, the hillock-rich sample exhibited a secondary Schottky barrier, which could be fitted with a modified thermionic emission model employing the Lambert W-function. Both polished and smooth sample showed nearly ideal thermionic emission with ideality factors $1.08$ and $1.03$, respectively. Compared with literature, all three diodes exhibit an improved Baliga Figure of Merit for diamond Schottky diodes with $V_{\text{BD}} > 2 \text{ kV}$., Accepted April 20, 2020

A summary of photo- and electrochemical surface modifications applied on single-crystalline chemical vapor deposition (CVD) diamond films is given. The covalently bonded formation of amine- and phenyl-linker molecule layers are characterized using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), cyclic voltammetry and field-effect transistor characterization experiments. Amine- and phenyl-layers are very different with respect to formation, growth, thickness and molecule arrangement. We detect a single molecular layer of amine linker-molecules on diamond with a density of about 1014 cm-2 (10 % of carbon bonds). Amine molecules are bonded only on initially H-terminated surface areas to carbon. In case of electrochemical deposition of phenyl-layers, multi-layer formation is detected due to three dimensional (3D) growths. This gives rise to the formation of typically 25 {\AA} thick layers. The electrochemical grafting of boron doped diamond works on H-terminated and oxidized surfaces. After reacting of such films with heterobifunctional crosslinker-molecules, thiol-modified ss-DNA markers are bonded to the organic system. Application of fluorescence and atomic force microscopy on hybridized DNA films show dense arrangements with densities up to 1013 cm-2. The DNA is tilted by an angle of about 35o with respect to the diamond surface. Shortening the bonding time of thiol-modified ss-DNA to 10 minutes cause a decrease of DNA density to about 1012 cm-2. Application of AFM scratching experiments show threshold removal forces around 75 nN for DNA bonded on phenyl linker-molecules and of about 45 nN for DNA bonded to amine linker-molecules. DNA sensor applications using Fe(CN6)3-/4- mediator redox-molecules, impedance spectroscopy and DNA-field effect transistor devices performances are introduced and discussed.

Conductive, boron doped diamond BDD is an extraordinary material with many applications in electrochemistry due to its wide potential window, outstanding robustness, low capacitance and resistance to fouling. However, in photoelectrochemistry, BDD usually requires UV light for excitation, which impedes e. amp; 8201;g., usage in CO2 to fuel reduction. In this work, a heavily boron doped, nanostructured diamond electrode with enhanced light absorption has been developed. It is manufactured from BDD by reactive ion etching and presents a coral amp; 8208;like structure with pore diameters in the nanometer range, ensuring a huge surface area. The strong light absorbance of this material is clearly visible from its black color. Consequently, the material is called Diamond Black DB . Electrochemical and X amp; 8208;ray photoelectron spectroscopy measurements performed at near amp; 8208;ambient pressure conditions of water vapor demonstrate increased surface reactivity for the hydrogen amp; 8208;terminated DB compared to oxidized surfaces. Depending on the surface termination, the wettability and hence the electrochemically accessible area can be changed. Photoelectrochemical conversion of CO2 was demonstrated using a Cu2O amp; 8208;modified electrode in ionic liquids under solar illumination. High formic acid production rates at low catalyst deposition times can be obtained paired with an increased catalyst stability on the DB surface

This paper summarizes recent progress in growth of ultra-pure CVD diamond, starting from the selection proper substrates to plasma treatments for the growth of dislocation-minimized diamond. Typical properties of ultra-pure diamonds are introduced like cathodoluminescence, carrier mobilities and optical absorption. The doping of diamond with nitrogen is the central topic of the second part. It covers incorporation probability, nitrogen atomic arrangements and detection schemata like IR and UV optical absorption. Finally, the formation of NV center in the bulk and close to the surface of diamond is introduced in combination with spin coherence properties, which are dominated by 13C, nitrogen, and phosphorus spin bathes. The properties of NV centers generated by implantation close to the surface are compared with bulk properties.

Schottky diodes fabricated on free-standing B doped monocrystalline diamond substrate have been investigated. As expected, reverse leakage current due to Schottky barrier lowering has been observed due to the high electric field at the metal-semiconductor interface. Forward current is highest under operating temperatures between 400 and 450K due to incomplete ionization hole mobility dependence on temperature. It is demonstrated that the static device characteristics in the temperature range from 300K to 450K can be modelled by parametrizing an analytical introduced for unipolar SiC and Si diodes.

Solid-state quantum emitters embedded in a semiconductor crystal environment are potentially scalable platforms for quantum optical networks operated at room temperature. Prominent representatives are nitrogen-vacancy (NV) centers in diamond showing coherent entanglement and interference with each other. However, these emitters suffer from inefficient optical outcoupling from the diamond and from fluctuations of their charge state. Here, we demonstrate the implementation of regular n-type gallium nitride nanowire arrays on diamond as photonic waveguides to tailor the emission direction of surface-near NV centers and to electrically control their charge state in a p-i-n nanodiode. We show that the electrical excitation of single NV centers in such a diode can efficiently replace optical pumping. By the engineering of the array parameters, we find an optical read-out efficiency enhanced by a factor of 10 and predict a lateral NV-NV coupling 3 orders of magnitude stronger through evanescently coupled nanowire antennas compared to planar diamond not covered by nanowires, which opens up new possibilities for large-scale on-chip quantum-computing applications.

We present a novel bonding process for gallium nitride-based electronic devices on diamond heat spreaders. In the proposed technology, GaN devices are transferred from silicon (Si) onto single (SCD) and polycrystalline diamond (PCD) substrates by van der Waals bonding. Load-pull measurements on Si and SCD heat spreaders at 3 GHz and 50 V drain bias show comparable power-added-efficiency and output power (Pout) levels. A thermal analysis of the hybrids was performed by comparison of 2 × 1mm2AlGaN/GaN Schottky diodes on Si, PCD, and SCD, which exhibit a homogeneous field in the channel in contrast to gated transistors. Significantly different currents are observed due to the temperature dependent mobility in the 2DEG channel. These measurements are supported by a 3D thermal finite element analysis, which suggests a large impact of our transfer technique on the thermal resistance of these devices. In summary, we show a promising new GaN-on-diamond technology for future high-power, microwave GaN device applications.

To improve the growth rate of diamond films, we grew single-crystalline (100) diamond films by hot-filament chemical vapor deposition (HFCVD), and investigated their growth mechanism. The methane/hydrogen concentration (CH4/H2) dependence of the growth rate was evaluated at a filament temperature of 3000 °C. The growth rate reached 17.9 μm/h at CH4/H2 = 5% and saturated at higher CH4/H2. We then investigated the filament-temperature dependence of the CH4 reaction rate at CH4/H2 = 5% (at which the methane supply is sufficient). The growth rate decreased with inverse filament temperature, indicating that the growth rate is governed by reactions on the filament surface. From the Arrhenius plot, the activation energy of diamond growth was estimated as 440 kJ/mol, close to that of CH4 → CH3⁎ + H⁎ decomposition. This result indicates that decomposition of CH4 and the formation of CH3 by the filament surface affect the growth rate of HFCVD-grown diamond.

Polishing diamond is the key process for diamond semiconductor research as well as gemology field. In this study, we proposed a novel method based on carbon solid solution into nickel (Ni) via high-temperature annealing, without mechanical damage formation. Single-crystal (100) diamond substrates were surface-planarized by putting them in contact with flat and mirror-surface Ni substrates via thermal annealing; the sample prepared through two annealing steps, at 1150 °C for 4 h and then at 900 °C for 4 h, exhibited the best surface morphology compared with the unannealed and one-step annealed (at either temperature) ones. For the diamond substrate with two-step annealing process, the surface roughness, measured in terms of root mean square roughness (Sq) via laser microscopy (LM) analysis over a scanning area of 129 × 130 μm2, was reduced by almost one order of magnitude compared to the unannealed sample (i.e., from ~0.67 to 0.07 μm). Moreover, atomic force microscopy (AFM) over a scanning area of 300 × 300 nm2 revealed a local reduction of Sq down to 0.62 nm. Then, diamond surfaces prepared via the proposed method and mechanical polishing were irradiated with hydrogen plasma to examine and compare their surface damages. The mechanical-polished sample showed characteristic linear and deep pits that, in contrast, were not observed on the two-step annealed sample, which, in comparison, also exhibited a density of shallow V-shaped pits of typical ~104–105 cm−2 which is about two orders of magnitude lower.

In this study, we report originally the excellent electrochemical performance of a micro-supercapacitor based on diamond-coated silicon nanowire (SiNW) electrodes using an aqueous electrolyte (0.1 M LiClO4). The deposition of a nanometric boron-doped diamond coating on SiNWs allowed the enlargement of the electrochemical window up to 3 V maintaining an extraordinary capacitive electrochemical response due to its high overvoltage. Thereby, the device exhibited an areal capacitance of 0.4 mF cm-2, a high power density of 50 mW cm-2 as well as an outstanding cycling stability after 2·106 galvanostatic charge-discharge cycles at a high current density of 10 mA cm-2. In addition, an ultra-fast charge-discharge rate was determined to be 1.5 ms, demonstrating the supercapacitor's enormous ability to deliver high power values at very rapid pulse times (Pmax: 321 mW cm-2). These results also evidence the potential of diamond coating to overcome the main drawbacks of silicon (e.g. rapid silicon oxidation due to presence of water) to be employed in aqueous electrolyte supercapacitors. Consequently, the role of diamond paves the way to high performance SiNW-based micro-supercapacitor development at large electrochemical windows in aqueous electrolytes, which are at present limited to 1 V.

We present a new approach combining top down fabrication and bottom up overgrowth to create diamond photonic nanostructures in form of single-crystalline diamond nanopyramids. Our approach relies on diamond nanopillars, that are overgrown with single-crystalline diamond to form pyramidal structures oriented along crystal facets. To characterize the photonic properties of the pyramids, color centers are created in a controlled way using ion implantation and annealing. We find very high collection efficiency from color centers close to the pyramid apex. We further show excellent smoothness and sharpness of our diamond pyramids with measured tip radii on the order of 10 nm. Our results offer interesting prospects for nanoscale quantum sensing using diamond color centers, where our diamond pyramids could be used as scanning probes for nanoscale imaging. There, our approach would offer signifikant advantages compared to the cone-shaped scanning probes which define the current state of the art., 6 pages, 4 figures

[Image: see text] Diamond is a highly attractive coating material as it is characterized by a wide optical transparency window, a high thermal conductivity, and an extraordinary robustness due to its mechanical properties and its chemical inertness. In particular, the latter has aroused a great deal of interest for scanning probe microscopy applications in recent years. In this study, we present a novel method for the fabrication of atomic force microscopy (AFM) probes for force spectroscopy using robust diamond-coated spheres, i.e., colloidal particles. The so-called colloidal probe technique is commonly used to study interactions of single colloidal particles, e.g., on biological samples like living cells, or to measure mechanical properties like the Young’s modulus. Under physiological measurement conditions, contamination of the particle often strongly limits the measurement time and often impedes reusability of the probe. Diamond as a chemically inert material allows treatment with harsh chemicals without degradation to refurbish the probe. Apart from that, the large surface area of spherical probes makes sensitive studies on surface interactions possible. This provides detailed insight into the interface of diamond with other materials and/or solvents. To fabricate such probes, silica microspheres were coated with a nanocrystalline diamond film and attached to tipless cantilevers. Measurements on soft polydimethylsiloxane (PDMS) show that the manufactured diamond spheres, even though possessing a rough surface, can be used to determine the Young’s modulus from a Derjaguin-Muller-Toporov (DMT) fit. By means of force spectroscopy, they can readily probe force interactions of diamond with different substrate materials under varying conditions. The influence of the surface termination of the diamond was investigated concerning the interaction with flat diamond substrates in air. Additionally, measurements in solution, using varying salt concentrations, were carried out, which provide information on double-layer and van-der-Waals forces at the interface. The developed technique offers detailed insight into surface chemistry and physics of diamond with other materials concerning long and short-range force interactions and may provide a valuable probe for investigations under harsh conditions but also on biological samples, e.g., living cells, due to the robustness, chemical inertness, and biocompatibility of diamond.

Direct low-temperature bond technologies for III-nitride thin film devices are of great interest to both improve device performance and enable on-wafer integration with other semiconductor technologies. However, thin films released from their growth substrate are rather rough and difficult to prepare for direct bonding. Here, we present a bond technique, which transforms a thin AlN surface layer into a 30 nm solid aluminum hydroxide bond layer. This chemical process is based on the dissolution of AlN and recrystallization of aluminum hydroxides within several nanometers of interfacial water, thereby restructuring and adapting the interfaces to form a homogeneous bond contact without any interfacial voids. AlGaN/GaN microwave transistors bonded on diamond demonstrate an excellent electrical, thermal, and mechanical performance of this bond technology for high-frequency devices as well as many other III-nitride applications.Direct low-temperature bond technologies for III-nitride thin film devices are of great interest to both improve device performance and enable on-wafer integration with other semiconductor technologies. However, thin films released from their growth substrate are rather rough and difficult to prepare for direct bonding. Here, we present a bond technique, which transforms a thin AlN surface layer into a 30 nm solid aluminum hydroxide bond layer. This chemical process is based on the dissolution of AlN and recrystallization of aluminum hydroxides within several nanometers of interfacial water, thereby restructuring and adapting the interfaces to form a homogeneous bond contact without any interfacial voids. AlGaN/GaN microwave transistors bonded on diamond demonstrate an excellent electrical, thermal, and mechanical performance of this bond technology for high-frequency devices as well as many other III-nitride applications.

Diamond is a key material for quantum devices and sensors, microelectromechanical systems, and the next-generation electronic devices. Microfabrication technology of single-crystal diamond (SCD) for device fabrication and processing is required but hardly established. For example, photolithographic techniques using plasma induced etching for the microfabrication of the diamond devices induce damage to its diamond and deteriorate the device-performances. To overcome this problem, we proposed a plasma-free imprint lithographic technique of SCD using nickel (Ni) mold at high temperatures. Prior to contacting with SCD, the native surface oxide film of the Ni mold was reduced by a hydrogen annealing treatment. Then, the samples were contacted with Ni mold closely, and annealed at various temperatures from 800 to 1200 °C for 30 min, aiming at the formation of the microstructure on the SCD surface by imprinting the structure of Ni mold based on the carbon solid solution reaction into Ni. After removing the Ni and the formed graphite by acid treatment from the SCD surface annealed at 1000 °C, imprints with Ni shape structure are revealed on the SCD surface. This microstructure formation processes requires only short periods of time without any specific equipments. Therefore, this diamond imprint lithography is significant and practical for the development of diamond applications.

Diamond offers superior material properties for realizing advanced integrated optical components. Particularly attractive is its wide transparency window which covers visible and infrared wavelengths. To take advantage of the potential for broadband waveguiding, diamond needs to be surrounded by broadband transparent cladding materials. Here we use diamond deposited onto aluminum nitride as a platform for integrated optics. We demonstrate essential photonic circuitry for coupling light into on-chip waveguides and show transmission both in the near-infrared and visible wavelength range. Our approach holds promise for functional diamond devices that cover spectral regions up to the mid-infrared. Left: Scanning electron micrograph of a diamond waveguide with an overlay of the mode profile. Right: material stack consisting of polycrystalline diamond (PCD) on aluminum nitride (AlN) on silicon (Si) (not to scale).

The silicon vacancy center (SiV) in diamond is promising for future quantum applications due to its unique properties like narrowband emission in the near infrared regime at 738 nm and photostability at room temperature. In this paper we investigate the photoluminescence and electroluminescence properties of SiV centers incorporated into the intrinsic-layer of single crystalline diamond p–i–n junction diodes via in-situ doping during CVD-growth. The experiments reveal electrical excitation of the SiV emission by applying forward currents. The electroluminescence and photoluminescence properties are compared and discussed.

Color centers in diamond nanoparticles are promising photoluminescence sources for various applications like bioimaging and labelling. In this work, Silicon Vacancy (SiV) centers were incorporated into individual diamond nanoparticles via controlled background doping during the CVD growth process. The size of the nanoparticles is measured with a scanning electron microscope whereas the SiV centers are characterized by photoluminescence measurements. Due to the low temperature growth conditions applied, the nanoparticles could be removed from the substrate via an annealing step and ultrasonic treatment, creating a suspension of fluorescent diamond nanoparticles.

The influence of temperature, pressure and holder geometry on the homoepitaxial single crystalline diamond growth in a microwave-assisted chemical vapor deposition reactor will be introduced and discussed in detail. Optimized diamond growth conditions were determined for homoepitaxy on (100)-oriented high-temperature high-pressure (HPHT) seed crystals using Raman scattering and confocal-micro-photoluminescence spectroscopy measurements.

We demonstrate the successful chemical vapor deposition of pinhole-free extremely thin (10–50 nm) nanocrystalline diamond (NCD) films to examine the potential of electrostatic self-assembly seeding with increased salt concentration of nanodiamond colloids as a nucleation enhancement step. The deposited films are characterized by scanning electron microscopy (SEM) and Raman spectroscopy to evaluate their surface morphologies and crystalline qualities. To carefully detect pinholes which are invisible via SEM, linear sweep voltammetry and cyclic voltammetry are also performed on the NCD film surfaces using the electrochemical oxidation of underlying silicon substrates. These investigations reveal that ~ 30 nm thick continuous NCD films are successfully obtained and completely pinhole-free ~ 50 nm thick films are reliably accessible via the proposed seeding technique.

Silicon nanowires (SiNWs) were successfully coated by uniform, adherent and homogenous ultra-thin crystalline diamond films through microwave enhanced chemical vapor deposition (MWCVD). The as-grown functionalized nanowires were employed as electrodes in a symmetric micro-supercapacitor (MSC) using a protic ionic liquid electrolyte [triethylammonium bis(trifluoromethylsulfonyl)imide; Et3NH TFSI]. The electrochemical performance of the device delivered a specific capacitance of 1.5 mF cm−2 and a power density of 25 mW cm−2 using an enlarged cell voltage of 4 V. Furthermore, a remarkable cycling stability was evaluated after 1 · 106 galvanostatic cycles at a high current density of 10 mA cm−2 with an excellent capacitive behavior. These results confirm that diamond-coated SiNW micro-supercapacitors exhibit very promising performances dealing with MSCs based on CVD-grown SiNWs. Keywords: Supercapacitors, Ionic liquid, Diamond, Silicon nanowires

In this paper we present nanocrystalline boron-doped diamond nanoelectrode arrays (BDD-NEAs) for the low-level detection of biogenic substances such as dopamine (DA) without the need for a selective membrane. We achieved a sensitive and reproducible detection of dopamine in the presence of ascorbic acid (AA) with oxygen (O-) terminated BDD-NEAs. To improve the peak separation between dopamine and ascorbic acid, differential pulse voltammetry (DPV) was employed. Therewith, it was possible to measure dopamine with a sensitivity of 57.9 nA μM −1 cm −2 . The detection limit was less than 100 nM with a linear behavior up to a concentration of 20 μM. The choice of the appropriate termination, the combination of the advantages of nanoelectrode arrays together with the outstanding electrochemical properties of boron-doped diamond and the right measurement method allowed successful measurement of dopamine in physiological concentrations in the presence of ascorbic acid.

Diamond provides superior optical and mechanical material properties, making it a prime candidate for the realization of integrated optomechanical circuits. Because diamond substrates have matured in size, efficient nanostructuring methods can be used to realize full-scale integrated devices. Here we review optical and mechanical resonators fabricated from polycrystalline as well as single crystalline diamond. We present relevant material properties with respect to implementing optomechanical devices and compare them with other material systems. We give an overview of diamond integrated optomechanical circuits and present the optical readout mechanism and the actuation via optical or electrostatic forces that have been implemented to date. By combining diamond nanophotonic circuits with superconducting nanowires single photons can be efficiently detected on such chips and we outline how future single photon optomechanical circuits can be realized on this platform.

We employed a high temperature conductance method to investigate the interface state properties of the Al2O3/B-doped diamond MOS structure by considering the surface potential fluctuation. Based on Gaussian approximation of Nicollian's model and Brew's graphical approach, we analyzed the frequency dependent characteristics of parallel conductance (Gp/ω–f) at various gate voltages and extracted the energy distribution of interface state density (Dit), capture cross section (σp), time constant (τit), and the standard deviation of surface potential fluctuation (σs). The Dit extracted by the conductance method exhibited good agreement with that by the high-low method, whereas there exist large errors when surface potential fluctuation was not considered by using the conductance method. The capture cross section extracted by the conductance method was on the order of 10−17 cm2. From the energy dependence of the interface state time constant, the hole capture and emission follow the Shockley–Read–Hall statistics. σs decreases with the energy position away from the valence band edge (Ev) of diamond, indicating that donor-like traps are distributed in the Ev side of diamond.

U-shaped diamond trenches with vertical {111} sidewalls for power devices were successfully obtained by anisotropic etching of diamond (110) surfaces using Ni films in high-temperature (1000 °C) water vapor. The etching rate for the diamond (110) surfaces was estimated to be 3.8 μm/min on the basis of the relationship between etching time and etching depth of diamond trenches with (110) bottoms. These (110) bottoms gradually disappeared as the etching progressed. Finally, they completely vanished and each diamond trench was surrounded by four vertical {111} sidewalls and two slanted {111} sidewalls. The formation mechanisms of the U-shaped diamond trenches are also discussed on the basis of the experimental results.

Electrochemically switchable selective membranes play an important role in selective filtration processes such as water desalination, industrial waste treatment and hemodialysis. Currently, membranes for these purposes need to be optimized in terms of electrical conductivity and stability against fouling and corrosion. In this paper, we report the fabrication of boron-doped diamond membrane by template diamond growth on quartz fiber filters. The morphology and quality of the diamond coating are characterized via SEM and Raman spectroscopy. The membrane is heavily boron doped (> 1021 cm-3) with > 3 V potential window in aqueous electrolyte. By applying a membrane potential against the electrolyte, redox active species can be removed via flow-through electrolysis. Compared to planar diamond electrodes, the ~250 times surface enlargement provided by such a membrane ensures an effective removal of target chemicals from the input electrolyte. The high stability of diamond enables the membrane to not only work at high membrane bias but also to be self-cleaning via in situ electrochemical oxidation. Therefore, we believe that the diamond membrane presented in this paper will provide a solution to future selective filtration applications especially in extreme conditions.

We present the spectroscopy of the local paramagnetic spin bath in nitrogen-15 delta-doped (111) diamond using single shallow nitrogen-vacancy centers as sensors and probe the spin bath dynamics with double spin resonance schemes.

International audience; Diamond is a promising metal-free photocatalyst for nitrogen and carbon dioxide reduction in aqueous environment owing to the possibility of emitting highly reducing solvated electrons. However, the wide band gap of diamond necessitates the use of deep UV to trigger a photochemical reaction. Boron doping introduces acceptor levels within the band gap of diamonds, which may facilitate visible-light absorption through defect-based transitions. In this work, unoccupied electronic states from different boron-doped diamond materials, including single crystal, polycrystalline film, diamond foam, and nanodiamonds were probed by soft X-ray absorption spectroscopy at the carbon K edge. Supported by density functional theory calculations, we demonstrate that boron close to the surfaces of diamond crystallites induce acceptor levels in the band gap, which are dependent on the diamond morphology. Combining boron-doping with morphology engineering, this work thus demonstrates that electron acceptor states within the diamond band gap can be controlled.