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Photoluminescence of silicon vacancy centres as conceptual indicator for the condition of diamond protection coatings
摘要： Due to the outstanding properties polycrystalline diamond coatings are used for wear protection on tools and work pieces. Thereby adhesive and abrasive wear as well as spalling of the coating can lead to damage and downtimes of the working machines. By depositing silicon doped multilayer diamond coatings, an indication of the condition of the coatings could be achieved. In this study the behaviour and transmission of the zero-phonon line of silicon vacancy centres is investigated in doped multilayer diamond coatings. The in-situ silicon doped diamond coatings were synthesized in use of an atmospheric laser-based plasma chemical vapour deposition. Photoluminescence measurements were performed with an excitation area of 18 mm2 and a wavelength of 248 nm. While the photoluminescence of the doped layers conceptually proves suitability as an indicator for the condition of the coating, the undoped diamond layers in the coatings show a high transmissivity to the zero-phonon line for the used parameters.
关键词： Wear,Luminescent materials,Protective coating,Diamond films,Chemical vapour deposition
更新于2025-09-23 15:21:21
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[IEEE 2018 20th International Symposium on High-Current Electronics (ISHCE) - Tomsk, Russia (2018.9.16-2018.9.22)] 2018 20th International Symposium on High-Current Electronics (ISHCE) - Luminescence of Crystals Excited by a Excilamps
摘要： The photoluminescence spectra of six diamond samples under the action of excilamp radiation at wavelengths of 172, 206, 222, 282 and 308 nm was studied. The influence of the wavelength on the excitation of the centers of the band-A, the 3H center, and the 1.4 eV center is revealed. The luminescence of the 2.56 eV centers and the H3 center was observed for all excitation wavelengths.
关键词： diamond,photoluminescence,defect,vibronic system,excilamp,ultraviolet,spectroscopy
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Structural characterization and emission properties of phosphorus-doped NCD films
摘要： Phosphorus-doped NCD films were grown on n-type silicon substrate by plasma-enhanced CVD with H2, CH4, and PH3 gas mixture for cold cathode application. The structure properties were characterized by Raman spectroscopy with a green laser of 532 nm at room temperature, scanning electron microscope, transmission electron microscope, and electron energy-less spectroscopy. Grown films show a good conductivity and have a typical structure with a combination of sp3 diamond gains with size around 20-100 nm and sp2 grain boundaries. The electron emission properties were characterized as comparing with single crystal, NCD film, and tip-array NCD. The tip-array NCD shows good emission properties with lower threshold electric filed and higher saturation current.
关键词： Structural characterization,Nano crystal diamond (NCD),PECVD,electron emitter,Phosphorus doping
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Electron sources based on diamond pin-diodes
摘要： Efficient electron sources are of ongoing interest in particular for space and terrestrial power telecommunications and radar applications. With conventional cathode technology based on thermionic- and field electron emission a novel approach for direct electron emission is realized through a diamond pin diode. Electrons injected into the conduction band of the intrinsic layer of the diode can be released into vacuum with a negative electron affinity surface of the i-layer. The diamond pin diodes were prepared on boron doped (p-type) substrates with (111) surface orientation. A high purity intrinsic and a phosphorus doped diamond layer (n-type, ~400nm thickness) were deposited in dedicated PECVD systems, respectively. An additional contact layer comprised of nanostructured carbon was grown in a dedicated PECVD. The layered device was processed by lithography utilizing an aluminum hard mask to etch mesa structures with diameters ranging from 50μm to 200μm. The final devices were treated in a pure hydrogen plasma to induce the negative electron affinity properties of the i-layer. After an annealing step in high vacuum individual pin diodes were biased in forward current and voltages up to 20V. The observation of light from the diode was attributed to the UV exciton state and indicated bipolar transport. At a diode current of about 80mA an electron emission current of 25μA was observed from a single 200μm diameter diode.
关键词： Diamond,solid state electronics,doping,phosphorus,electron emission,plasma-enhanced chemical vapor deposition,nanostructured carbon,pin diode,single crystal
更新于2025-09-23 15:21:21
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Fabrication of Two-Dimensional Arrays of Fluorescent Centers in Single-Crystalline Diamond Using Particle Beam Writing
摘要： Micrometer-scale patterning was performed using the particle beam writing technique with a focused heavy-ion microbeam, allowing the creation of a unique two-dimensional distribution of fluorescent centers in single-crystalline diamond. The focused nitrogen microbeam was scanned over the target of single-crystalline diamond prepared by chemical vapor deposition to create nitrogen-vacancy (NV) centers at defined positions. Imaging using a custom-built confocal fluorescence microscopy system revealed that the desired NV distribution was generated in the target crystal with a spatial resolution similar to the beam resolution. A two-dimensional matrix barcode test pattern was successfully generated in a diamond substrate to demonstrate the encryption of information inside a solid-state target.
关键词： diamond,particle beam writing,two-dimensional,chemical vapor deposition,nitrogen vacancy centers,confocal fluorescence microscopy
更新于2025-09-23 15:21:21
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Influence of diamond tool chamfer angle on surface integrity in ultra-precision turning of singe crystal silicon
摘要： Ultra precision diamond machining enables the economical production of freeform optics on infrared materials such as silicon. To produce optics with acceptable surface integrity, it is important to have a good understanding of process-work material interaction between diamond tool and brittle and hard single crystal IR materials. Chamfered cutting edges are known to have high strength, which makes them suitable for machining difficult-to-cut materials. This study investigates the influence of chamfer angle on the surface integrity of silicon. Diamond tool chamfer angles of ? 20°, ? 30°, and ? 45° are considered under practical diamond turning conditions of single crystal silicon. State-of-the-art techniques were used to investigate the surface integrity of the machined silicon surfaces. The results show that chamfer angle of 30° yields more favorable results compared to 20° and 45° under the conditions tested. The results indicate the complex interplay between tool geometry and process parameters in reaching an acceptable level of surface integrity. A machinability map indicating ductile and brittle machining conditions for 30° chamfered diamond tool has been presented which includes directly transferable knowledge to the precision machining industry.
关键词： Silicon,Surface integrity,Phase transformation,Diamond machining
更新于2025-09-23 15:21:21
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The Infrared spectrum of very large (periodic) systems: global versus fragment strategies—the case of three defects in diamond
摘要： The calculation of the full vibrational spectrum (Infrared or Raman) of very large systems (say larger than one thousand atoms) is not only very expensive, but also of relatively low interest, as in many (most of the) cases only a subset of modes, well separated from the large, diffuse bands resulting from the superposition of thousands of peaks, is used for the spectroscopic characterization of the specific system under study. Here, a fragment strategy, consisting in computing and diagonalizing a reduced (in size) Hessian matrix centered around the zone of interest, is illustrated, and its accuracy and efficiency documented, by comparison with the full Hessian diagonalization (FHD) scheme. Three test cases are considered, showing different vibrational features. They are defects in diamond: the VN3 H defect (V stands for the vacancy), where the interesting point is the characterization of the bending and stretching modes of H, well separated from the large band resulting from the perturbation of the diamond manifold; the VH4 defect (four H atoms in the vacancy, with vibrational modes related to H appearing both at high and low wave numbers); and the I2N interstitial defect, with modes in which the N atoms are involved, appearing at wave numbers not far from the manifold of the perfect diamond modes. So the three cases, apparently similar, explore three different situations of interest for the fragment strategy: (1) localized modes very well separated from the large diamond continuous band ( VN3H); (2) modes at upper border of the large diamond continuous band ( I2N ): a case in which the modes of interest appear both as separated from and merged with the large continuous band ( VH4 ). It turns out that in all cases relatively small fragments, containing from 2 to 40 atoms, permit to reproduce with high accuracy (the difference with respect to the FHD being always smaller than 5 cm?1 for the wave numbers, and a few percent for the IR intensity) the spectral feature(s) of interest, at a computational cost that is only a small fraction of the one required by the FHD.
关键词： fragment strategy,vibrational modes,large systems,Infrared spectrum,diamond defects
更新于2025-09-23 15:21:21
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Reinforcement of a laser-textured 316L steel with CuCoBe-diamond composites through laser sintering
摘要： The aim of this work was the production and the characterization of a laser textured 316L stainless steel reinforced with CuCoBe-diamond composites by laser sintering. The composites were obtained from CuCoBe and synthetic diamond with different particle sizes by mechanical alloying. The influence of the reinforcement on the physical, chemical and surface properties was analyzed. The results showed that the textured pattern consisted of square pyramids with a machined area of approximately 80%. The interfaces between the steel and the reinforcement after sintering are well defined and sharp. A good adherence of the diamond particles to the CuCoBe matrix was achieved. The laser sintering process did not induce any phase transformations or oxidation of the reinforcement. The steel reinforced with the biggest diamond particles exhibited substantially better surface performance than the untextured material.
关键词： composites,sintering,diamond,steel,Mechanical,316L,CuCoBe,alloying,texturing,laser
更新于2025-09-23 15:21:01
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The influence of positive pulses on HiPIMS deposition of hard DLC coatings
摘要： Diamond-like carbon (DLC) coatings were deposited by a novel HiPIMS method that incorporates positive voltage pulses at the end of the conventional HiPIMS discharge. Different positive voltage amplitudes (100, 200, 300, 400 and 500 V) were used to evaluate the effect of this operation mode on the discharge process and the mechanical properties of the deposited DLC coatings. The application of positive pulses was observed to enhance the ionization of both the sputtered carbon and argon species. Mass spectroscopy measurements showed that a larger amount of high-energy C+ ions are generated, with ion energies proportional to the amplitude of the overshoot voltage. The ion bombardment induced by the positive pulses led to higher compressive residual stresses and densification of deposited DLC coatings. Moreover, their Raman spectra exhibited lower D-band and G-band intensity ratios (ID/IG) as the pulses voltage was increased which is indicative of higher sp3 content. Mechanical properties were evaluated by nanoindentation testing and the hardness of the deposited DLC films was observed to increase from 9.6 GPa (for no voltage pulse applied) to 22.5 GPa (for an applied positive pulse voltage of 500 V).
关键词： HiPIMS,Hard coatings,Diamond-like Carbon (DLC),Tribology
更新于2025-09-23 15:21:01
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Ellipsometry - Principles and Techniques for Materials Characterization || Spectroscopic Ellipsometry - Application on the Classification of Diamond-Like Carbon Films
摘要： Diamond-like carbon (DLC) films have been spreading from their theoretical basis to worldwide industrial applications because of their unique properties. Since their properties depend strongly on the conditions of synthesis, the effective classification of DLC films becomes quite necessary. From the ternary phase diagram to the Japan New Diamond Forum standard, the classification attempts are also accompanied by the continuous development of their applications. Generally, the hydrogen content and sp3/(sp2 + sp3) ratio are the primary parameters for their classification. However, researchers are afraid that currently sp3/(sp2 + sp3) ratio estimated included not only network sp3 but also sp3 hybrid carbons in the hydrogen-terminated cluster. Simultaneously, the above classification methods need to use the large equipment, such as the synchronous radiation source. Therefore, to realize more straightforward to classify DLC films efficiently, the optical constants (refractive index (n) and extinction coefficient (k)) have been proposed in 2013 to be effective method to classify the DLC films, for which a lot of considerable discussion in the past ISO/TC-107 meetings has been made. The purpose of this chapter is to introduce the latest developments of optical constants on the classification of DLC films and explore their relationship with the current standard.
关键词： spectroscopic ellipsometry,diamond-like carbon film,classification
更新于2025-09-23 15:21:01