Articles

Diamond is valuable material with extraordinary high thermal conductivity and transparency in a wide spectral range from UV to IR and longer wavelengths. Defects and impurities in the diamond lattice can absorb and emit light at wavelengths specific for each of such “color centers.” Particularly, the vacancy-related defects in diamond, such as nitrogen-vacancy (NV) or silicon-vacancy (SiV) centers, are actively investigated due to their potential for biomedicine, quantum optics, local thermometry and magnetometry. Although a great variety of different color centers in diamond are discovered, only a limited number of those point defects can be reliably reproduced in synthetic diamond, obtained either by chemical vapor deposition (CVD) or high-pressure high-temperature (HPHT). An alternative approach to producing luminescent diamond-based materials is to integrate stable non-diamond sources of luminescence in the form of nano- or microparticles of foreign materials into the pristine diamond. The produced diamond composites possess excellent properties of diamond combined with optical emission characteristics, which cannot be provided with intrinsic defects in diamond. The good candidates for the materials of such impurities are well-investigated fluorides and oxides doped by rare-earth elements (RE) or other luminescent chalcogenides such as sulfides, selenides and tellurides. Here we briefly review recent achievements in fabrication and properties of these new luminescent diamond-RE composites, compare them with luminescent properties of doped diamond, and outline prospects for applications of the luminescent diamond composites for photonics, markers, monitors of high-power synchrotron, X-ray beams and X-ray lasers.

Diamond field-effect transistor (FET) has great application potential for high frequency and high power electronic devices. In this work, diamond FETs were fabricated on (0 0 1) single crystal diamond with homoepitaxial layer. The nitrogen impurity content in the homoepitaxial layer is greatly decreased as measured by the Raman and photoluminescence spectra. The diamond field effect transistor with 100 nm Al2O3 as gate dielectric shows ohomic contact resistance of 35 Ω . mm, maximum drain saturation current density of 500 mA/mm, and maximum transconductance of 20.1 mS/mm. Due to the high quality of Al2O3 gate dielectric and single crystal diamond substrate, the drain work voltage of −58 V is achieved for the diamond FETs. A continuous wave output power density of 4.2 W/mm at 2 GHz is obtained. The output power densities at 4 and 10 GHz are also improved and achieve 3.1 and 1.7 W/mm, respectively. This work shows the application potential of single crystal diamond for high frequency and high power electronic devices.

Ferri/ferro-cyanide ([Fe(CN)6]3−/4−) redox couple has been extensively used as a benchmark to assess electrocatalytic degradation capability of boron-doped diamond (BDD) electrodes. However, the [Fe(CN)6]3−/4− is far more sensitive to the surface terminal groups of BDD surface than the other factors (e.g. surface morphology and electrode configuration) that are closely related to electrocatalytic degradation properties. Thus, inconsistency exists while correlating the degradation properties of BDD with electrochemical properties determined from ferri/ferro-cyanide redox couple. Herein, an exemplar pollutant, reactive blue 19 (RB-19), was electrochemically degraded using various terminated BDD electrodes, including hydrogen-terminated (H-BDD), oxygen-terminated (O-BDD) and porous oxygen-terminated BDDs (OE-BDD), obtained via cathodic and anodic polarization as well as oxygen plasma etching, respectively. Surprisingly, OE-BDD with the lower heterogeneous electron transfer rate constant for [Fe(CN)6]3−/4− showed a better electrocatalytic degradation capability toward RB-19, indicating the inconsistency for qualitatively evaluating degradation properties according to the kinetic parameters extracted from [Fe(CN)6]3−/4− redox system.

Semiconductor devices generally take advantage of the charge of electrons, whereas magnetic materials are used for recording information involving electron spin. To make use of both charge and spin of electrons in semiconductors, a high concentration of magnetic elements can be introduced in nonmagnetic III-V semiconductors to make magnetic semiconductor. In this work, Fe-Diamond was obtained with low solubility by modified microwave plasma chemical vapor deposition technique. Magnetic measurements revealed that the magnetic transition temperature from paramagnetic to ferromagnetic-like is above room temperature. The bandgap of Fe-Diamond is calculated to be 1.65 eV, which indicates that Fe-Diamond is a room temperature diluted ferromagnetic semiconductor.

The sensitivity of practical solid quantum sensing can be boosted up by increasing the number of probes. However, the effects of spin dephasing caused by inhomogeneous broadening and imperfect quantum control can reduce the fidelity of quantum control and the sensitivity of quantum sensing with the dense ensemble of probes, such as nitrogen-vacancy (NV) centers in diamond. Here, we present a robust and effective composite-pulse for high fidelity operation against inhomogeneous broadening and control errors via optimized modulation of the control field. Such a composite-pulse was verified on NV center to keep high fidelity quantum control up to a spectrum detuning as large as 110% of Rabi frequency. The sensitivity of the magnetometer with NV center ensemble was experimentally improved by a factor of 4, comparing to dynamical decoupling with a normal rectangular pulse. Our work marks an important step towards high trustworthy ultra-sensitive quantum sensing with imperfect quantum control in practical applications. The used principle is universal and not restricted to NV center ensemble magnetometer.

Herein, the mid-infrared (7.7–13.7 μm) diamond-based phase shifter was designed and optimized by finite-element analysis. The ridge-shaped diamond waveguide is designed and doped to form the internal p–n structure, and the internal carrier distribution is changed by applying forward and reverse voltages to change the effective refractive index to achieve the effect of π-phase shift. The results show that when p-doping concentration is 4 × 1017 cm−3 and n doping concentration is 1 × 1018 cm−3, upon the reverse voltage (8 V) is applied, the change of the real part of effective refractive index (ΔR) is 1.6 × 10−5, and the length of the phase shifter (L) required to realize the π-phase shift is 241 mm; upon the forward voltage (–8 V) is applied, ΔR increases to 3.2 × 10−4, and the length of the phase shifter required is shortened to 12.03 mm. Such a short length is relatively easy in industrial production. In order to make the refractive index distribution more uniform, the carrier concentration has been optimized as 1 × 1017 cm−3 for p-type and 4 × 1017 cm−3 for n-type, respectively.

A new technique of diamond and InGaP room temperature bonding in atmospheric air is reported. Diamond substrate cleaned with H2SO4/H2O2 mixture solution is bonded to InGaP exposed after removing the GaAs layer by the H2SO4/H2O2/H2O mixture solution. The bonding interface is free from interfacial voids and mechanical cracks. An atomic intermixing layer with a thickness of about 8 nm is formed at the bonding interface, which is composed of C, In, Ga, P, and O atoms. After annealing at 400 °C, no exfoliation occurred along the bonding interface. An increase of about 2 nm in the thickness of the atomic intermixing layer is observed, which plays a role in alleviating the thermal stress caused by the difference of the thermal expansion coefficient between diamond and InGaP. The bonding interface demonstrates high thermal stability to device fabrication processes. This bonding method has a large potential for bonding large diameter diamond and semiconductor materials.

As a fascinating nanocarbon photocatalytic material, nanodiamonds (NDs) have attracted more and more attention recently due to their high chemical stability, high carrier mobility, narrowing band gap, easy surface modification, and mass production. This review summarizes the latest progress related to elaborated construction of NDs and NDs-based nanocomposite, including microstructure regulation of pristine NDs, elemental doping and formation a heterojunction by coupled with another semiconductor. The construction and properties of each category of NDs-based material are reviewed on their structure, preparation methods, texture control, and photocatalytic performance. Photocatalytic applications of NDs-based nanomaterials for hydrogen evolution from water splitting, organic pollution degradation, CO2 reduction, N2 reduction, graphene oxide reduction, and the latest advances in photocatalytic reaction mechanism have been also systematically reviewed. Finally, the challenges and prospects of the photocatalytic application of NDs are also briefly analyzed.

In this article, a series of highly boron-doped diamond ([B] > 1021 cm−3) electrodes with small gradient variations in boron concentration were prepared by hot filament chemical vapor deposition (HF-CVD). Reactive blue 19 (RB-19) dye solution was used as a prototype wastewater. Interestingly, we found that the electrochemical properties (electrochemically active surface area and oxygen evolution potential) and the electrochemical degradation performance did not deteriorate linearly with increasing boron concentration. Specifically, the electrochemically active surface area of the electrode at [B]/[C] = 50,000 ppm was the highest of 9.366 cm2, the chromaticity removal rate of RB-19 dye wastewater reached 100% after 90 min, and the TOC removal rate reached 74.48% after 180 min with the lowest energy consumption.

Active phased array antenna typically featured high performance, high device integration, and high heat flux, making it difficult to dissipate heat. Diamond, the substance with the closest arrangement of atoms in nature, has the advantages of a high thermal conductivity and strong adaptability to the space environment. The batch applications of high-thermal-conductivity diamonds for the thermal management of the phased array antennas of the inter-satellite links were introduced in this paper. The diamond was developed by the direct-current arc-plasma chemical vapor deposition method. The product size, thermal conductivity, precision, and application scale all met the engineering requirements. The high-precision assembly of the diamond and the structural frame enabled the efficient heat collection and transfer from the distributed point heat sources of multiple transmit/receive (T/R) modules. Verified on the ground, the thermal matching design between the diamond and the metal frame exhibited an outstanding heat dissipation performance. After four satellites using the diamonds were launched, the flight data showed good antenna thermal control, with temperature gradients of the T/R modules less than 2.2 °C, further verifying the rationality and effectiveness of using high-thermal-conductivity diamonds in the thermal design and implementation of antennas.