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Direct writing of single germanium vacancy center arrays in diamond
摘要： Single photon emitters in solid-state systems with superior optical properties are of fundamental importance for they are building block candidates of many quantum optics applications. The ideal qubit will have a bright narrow band emission (i.e. high Debye Waller (DW) factor) and an access to optically read out and manipulate its spin states. Numerous candidates have been studied in diamond including the nitrogen vacancy (NV) center and more recently the silicon vacancy (SiV) center. The advantage of the SiV is its high DW factor, with nearly 80% of its emission is within its zero phonon line (ZPL). But its coherence time is limited by the narrow ground state splitting (~40 GHz) which favors single-phonon absorption from the lower branch to the upper one. This necessitates the search for an alternative system with a larger ground state splitting to suppress the phonon-mediated processes. Color centers in diamond are promising solid-state qubits for scalable quantum photonics applications. Amongst many defects, those with inversion symmetry are of an interest due to their promising optical properties. In this work, we demonstrate a maskless implantation of an array of bright, single germanium-vacancy (GeV) centers in diamond. Employing the direct focused ion beam technique, single GeV emitters are engineered with the spatial accuracy of tens of nanometers. The single GeV creation ratio reaches as high as 53% with the dose of 200 Ge+ ions per spot. The presented fabrication method is promising for future nanofabrication of integrated photonic structures with GeV emitters as a leading platform for spin-spin interactions.
关键词： diamond,germanium-vacancy centers,single photon emitters,quantum photonics,focused ion beam
更新于2025-09-09 09:28:46
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Strain engineering for thermal conductivity of diamond nanothread forests
摘要： Thermal properties of the diamond nanothread (DNT) forest array are studied using non-equilibrium molecular dynamics simulations. We find a strong anisotropic thermal property in this structure, i.e. the thermal conductivity in thread direction is over 300 times of that in the perpendicular direction. When subject to external strain, the thermal conductivity of the DNT forest decreases with increasing compressive/tensile strain in the thread direction, while thermal conductivity increases exponentially with increasing compressive strain in the perpendicular direction. The increase in thermal conductivity is attributed to the enhanced interactions among DNTs induced by compression. These results are explained by phonon spectra and structural deformation. Our findings show that diamond nanothread forest has a great potential application in the super-capacitors.
关键词： Anisotropy,Diamond nanothread,Thermal conductivity,Molecular dynamics
更新于2025-09-09 09:28:46
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Ductile behavior of optical glass in single point diamond turning
摘要： Single point diamond turning tests were carried out on a B270 type glass. Sub-micrometer cutting conditions were applied in order to generate ductile response during single point machining. The profile generated by the rapid removal of the tool tip from the machined surface, analyzed by atomic force microscopy, showed that the brittle-to-ductile transition occurs at a few tenths of micrometers. According to the machining results, the maximum feed rate capable of generating a ductile mode machining behavior is of 0.9 micrometer/revolution. Furthermore, it was shown that with the cutting depth lower than 0.100 micrometer/revolution, the material removal mechanism is totally ductile. Ribbon-like chips were not observed when ductile machining was performed, as commonly seen during ductile machining of semiconductor crystals. The chips removed had a small needle-like shape. This material’s fragile behavior during machining may be related to high densification during tool/material interaction with subsequent elastic recovery response.
关键词： soda-cal-silicates,Atomic Force Microscope,Brittle-to-ductile transition,diamond turning
更新于2025-09-09 09:28:46
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Quantum behavior of hydrogen-vacancy complexes in diamond
摘要： Hydrogen plays an essential role in the growth process of artificial diamond and can easily form complexes with lattice vacancies. Despite substantial efforts to resolve the electronic structure and the ground-state properties of the hydrogen-vacancy (HV) center, the final remarks are ambiguous, while the complexes of vacancy with two and more hydrogen atoms remain unexplored. In this paper, we used spin-polarized, hybrid density-functional theory method to investigate electronic structure and magneto-optical properties of various hydrogen-vacancy clusters in diamond. Our theoretical results indicate a very strong tendency toward the formation of HnV complexes up to four hydrogen atoms that are mostly electrically and optically active centers. One of the investigated defects introduce highly correlated electronic states that pose a challenge for density-functional theory and, therefore, require special treatment when charge- and spin-density-related properties are determined. We introduced an extended Hubbard model Hamiltonian with fully ab initio provided parameters to analyze the complex electronic structure of highly correlated H2V0 defects. The role of quantum tunneling of hydrogen in HV center and its impact on the hyperfine structure was discussed. We demonstrate that experimentally observed HV1? center is similar to well-known NV1?, i.e., I) it possesses triplet 3A ground state and 3E excited state in C3v symmetry; II) the calculated zero-phonon line is 1.71 eV (1.945 eV for NV1?). A detailed experimental reinvestigation based on optically detected electron paramagnetic resonance spectroscopy is suggested to verify whether the HV1? center has metastable singlet shelving states between the ground and excited state triplets and, as a result, whether it may exhibit a spin-selective decay to the ground state.
关键词： quantum tunneling,diamond,hydrogen-vacancy complexes,magneto-optical properties,density-functional theory,quantum behavior
更新于2025-09-09 09:28:46
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Synthesis of nanopolycrystalline mesoporous diamond from periodic mesoporous carbon: Mesoporosity increases with increasing synthesis pressure
摘要： We report the catalyst-free synthesis of monolithic mesoporous nanopolycrystalline diamond from periodic mesoporous carbon at pressures between 15 and 21 GPa and a temperature of 1300 °C. We investigated the pressure-dependence of the porosity with 3-dimensional electron tomography. We have observed that surface areas increase from 56 to 90, 138 m2 g?1, and porosities increase from 10, 24, to 33% for materials produced at 15, 18, and 21 GPa, respectively. The increased porosity at higher pressure may be due to the earlier onset of the nucleation of diamond at higher pressure.
关键词： Synthesis,Diamond,Nanopolycrystalline,Electron tomography,Mesoporous
更新于2025-09-09 09:28:46
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Noise spectroscopy of a quantum-classical environment with a diamond qubit
摘要： Knowing a quantum system’s environment is critical for its practical use as a quantum device. Qubit sensors can reconstruct the noise spectral density of a classical bath, provided long enough coherence time. Here, we present a protocol that can unravel the characteristics of a more complex environment, comprising both unknown coherently coupled quantum systems, and a larger quantum bath that can be modeled as a classical stochastic field. We exploit the rich environment of a nitrogen-vacancy center in diamond, tuning the environment behavior with a bias magnetic field, to experimentally demonstrate our method. We show how to reconstruct the noise spectral density even when limited by relatively short coherence times, and identify the local spin environment. Importantly, we demonstrate that the reconstructed model can have predictive power, describing the spin qubit dynamics under control sequences not used for noise spectroscopy, a feature critical for building robust quantum devices. At lower bias fields, where the effects of the quantum nature of the bath are more pronounced, we find that more than a single classical noise model are needed to properly describe the spin coherence under different controls, due to the back action of the qubit onto the bath.
关键词： nitrogen-vacancy center,diamond qubit,noise spectroscopy,dynamical decoupling,quantum-classical environment
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - The use of Films of Metal-Containing Nanocomposites with a Silicon-Carbon Matrix in Thermal Imitators of the Components of Micro-and Nanoelectronics
摘要： The installation scheme and features of the technology for obtaining alloyed diamond-like silicon-carbon films are presented and the heating elements based on these films are created to be used as thermal imitators of micro- and nanoelectronical products and their modules with increased specific heat flux (such as microprocessors, high-frequency microcircuits of the transmit-receive modules, LEDs, lasers, etc.). The matrix of the alloyed diamond-like silicon-carbon film has an amorphous nanocomposite structure, into which the inclusions having nanodimensions and composed of chromium and its compounds with carbon are introduced. Due to the controlled change in the parameters of the process of film deposition, it is possible to obtain a given specific resistance of a doped diamond-like silicon-carbon film over a wide range: from 10-4 to 1014 (cid:525)·cm. The electrical resistance of the manufactured heating elements with dimensions of 7x30x1 mm on the basis of a diamond-like silicon-carbon film 1 (cid:541)m thick, doped with chromium, was 15 (cid:525). Using four such heating elements with a total resistance of 60 ohms made it possible to create a compact detachable thermal imitator of the electronic module with a maximum power of 806 W. Application of the developed thermal imitator accelerates the process of research and improvement of heat sink devices for products of micro- and nanoelectronics.
关键词： heating element,thermal imitator,micro- and nanoelectronical products,alloyed diamond-like carbon-graphite nanocomposite structure
更新于2025-09-09 09:28:46
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Design, development and use of the spectrometer for investigating coherent THz radiation produced by micro-bunching instabilities at Diamond Light Source
摘要： Schottky barrier diodes (SBDs) are known for their low noise, ultra-fast response and excellent sensitivity. They are often implemented as detectors in the millimetre wavelength regime. Micro-bunch instabilities (MBI) have been detected at many light sources around the world including the Diamond Light Source, UK. These MBI can result in bursts of coherent synchrotron radiation (CSR) with millimetre wavelengths. More research needs to be carried out with regards to the dynamics of MBI in order to con?rm the simulations and to eventually harness the power of the CSR bursts. A single shot spectrometer has been designed and is under operation at the Diamond Light Source (DLS). It is composed of eight SBDs ranging from 33-1000 GHz. Unlike previous measurements carried out, each of the SBDs has been individually characterised thus making the results obtained comparable to simulations. In this paper, we present the assessment of each SBD in the spectrometer and the ?rst results of the spectrometer’s use in the beam.
关键词： Schottky barrier diodes,micro-bunch instabilities,spectrometer,coherent synchrotron radiation,Diamond Light Source
更新于2025-09-09 09:28:46
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High performance single crystalline diamond normally-off field effect transistors
摘要： High performance normally-off hydrogen-terminated diamond (H-diamond) MOSFETs were fabricated on single crystalline diamond grown in our lab. The device with 2-μm gate length shows threshold voltage of -1.0 V, and a drain current of 51.6 mA/mm at VGS = VDS = ?4.5 V and an on-resistance of 65.39 Ω·mm. The transconductance keeps increasing when VGS shifts from VTH towards more negative direction, and reaches the record high value of 20 mS/mm at VGS of ?4.5 V, which benefitted from the almost constant mobility of the holes in the gate voltage range of -4 V < VGS < -2 V. The critical device process to realize these low on-resistance normally-off MOSFETs consists of 2-min UV ozone treatment of the H-diamond surface and thermal oxidation of aluminum film in the air to form an alumina gate dielectric.
关键词： MOSFET,Single crystalline diamond,normally-off
更新于2025-09-09 09:28:46
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Multiphonon Intracenter Relaxation of Boron Acceptor States in Diamond
摘要： The relaxation rates are calculated in the adiabatic approximation, in which the steady-state impurity states are taken to be electronic-vibrational (vibronic) states. The probabilities of transitions between these states with the emission (or absorption) of one or several phonons are calculated in first-order perturbation theory on the assumption that the transitions are a result of the violation of adiabaticity. The electron part of the wave function of the vibronic state is described by a simple Hamiltonian with an isotropic effective mass. The wave function of the ground state is determined by the quantum defect method. According to the calculations, a hole relaxes from the excited boron acceptor state, whose energy is 304 meV higher than the energy of the ground state, to the ground state with the emission of two optical phonons with a rate of ~1011 s–1. This value is an estimate from above, since the model of nondispersive optical phonons used in the study overestimates the number of phonon modes, whose participation in relaxation is allowed by the energy conservation law. However, despite the rough approximation, it can be concluded that the multiphonon relaxation of boron acceptor states in diamond is a fast process.
关键词： diamond,boron acceptor states,multiphonon relaxation,vibronic states,adiabatic approximation
更新于2025-09-09 09:28:46