Papers by Keyword: CVD Diamond

Abstract: The growth of diamond films on different substrates has been studied extensively to support the emerging technologies ranging from mechanical to nano/microelectronics. It is known that the performance of these applications is affected by diamond film properties, such as structure and morphology. Using chemical vapor deposition (CVD) technique, we have deposited ultrananocrystalline diamond (UNCD) and microcrystalline diamond (MCD) films on 4H-SiC substrates and investigated their basic material properties. The understanding and exploitation of the material properties are fundamental to evaluate the potential of UNCD-on-SiC and MCD-on-SiC structures for fabrication of electronic devices and sensors.

Abstract: This Research is Focused on the Chemical Mechanical Sharpening of CVD Diamond Micro Tool, which has High Strength and Good Wear Resistance. the Diamond Grinding Wheels were Usually Used for Sharpening, but this Method could Not get High Quality Surface of the Diamond Efficiently and Small Cutting Edge Radius. in Order to Seek a Better Mode for Sharpening, the Copper Based Tungsten Carbide Disc and Abrasive were Used for Grinding. for Better Understanding the Effects of Different Parameters on the Grinding Process and Optimizing them, the Orthogonal Method was Used to Design the Experiments. Grinding Direction, Feed Rate and the Grinding Velocity were Investigated to Obtain Sharper Cutting Edge and Smooth Flank Face. Analysis of Range was Also Introduced to Evaluate the Contribution of each Parameter in Orthogonal Experiment. the Results Showed that down Grinding, Medium Feed Rate and Low Velocity could Achieve a Better Sharpening Result.

Abstract: Microstructure patterning in single-crystal chemical vapor deposition (SC-CVD) diamond films was investigated to establish a direct patterning procedure by using proton beam writing with a focused microbeam of protons. Test microstructural patterns on SC-CVD diamond with different total fluences from 0.5 to 10 pC/μm² were formed with a probe diameter of approximately 1 μm, a maximum scanning area of 800 × 800 μm, and a beam current of up to 100 pA. The most intensively irradiated pattern with beam fluence of 10 pC/μm² was visualized with both transmission and reflection optical microscopy. The other patterns created with lower beam fluences were characterized by the changes in reflective index and were visible only in the transmission microscopy images. The depth of patterns was precisely controlled by changing proton energies in range of 0.75–3 MeV. The structures in depth from 5 to 45 μm were successfully observed in optical microscope images.

Abstract: This study is focused on the optimization of the grinding process parameters for the grinding of the CVD diamond micro-milling tool. Two types of CVD diamond i.e. CDM and CDE are used for the study. Feed rate and the grinding velocity are used as the grinding parameters. The optimizations of the parameters are done by studying the two results i.e. grinding force and cutting edge radius. Highest grinding velocity and medium feed rate is found to have the best result for the grinding of the CVD diamond. Keywords: CVD diamond, Grinding, Micro-tool

Abstract: CVD diamond is the main trend of future diamond materials. Surface uniformity of CVD diamond film polishing is one of the key technologies to expand the application of CVD diamond. Based on the catalytic polishing method, rotation velocity of the planet wheel is achieved when the lapping plate is in different rotation velocity and different bias distance by mechanics analysis. The lapping surface uniformity is analyzed to find out the best bias distance and velocity ratio by simulating the lapping times of different CVD diamond film with different velocity ratio and bias distance. At last, the lapping planet velocity and bias distance are achieved when polishing is in the best condition. The high uniformity surface can be achieved when polishing is carried out in these parameters.

Abstract: A prototype sensor able to work at zero bias has been fabricated using high quality single crystal diamond and two Schottky junctions. The detector's current in the dark is 3.2±0.2×10^-14 A, while the current measured under irradiation with 1.6 Gymin^-1 of 6 and 15 MV x-ray photons is 7.5±0.2×10^-10 A. The sensitivity is strongly dependent on the applied voltage whereas at zero bias we have measured 37±2 nCGy^-1, independent of the beam quality. The sensitivity increases with a sub-linear trend up to 100V, as the sensor photocurrent dependence on voltage. Moreover, the device shows very fast response on the rise and fall transients, with the signal stability under irradiation better than 0.3%. The linearity with the dose rate is spread over three orders of magnitude from 1.3×10^-3 Gymin^-1 to 1.2 Gymin^-1 as measured with Co-60 photons.

Abstract: In order to realize a smart nano-machining and measurement system based on atomic force microscope (AFM), we have been developing diamond probes with a high-aspect-ratio, sharpened diamond tip. In this paper, we described the most important micromachining techniques for the fabrication of the diamond probes. The high-aspect-ratio diamond microstructures were successfully fabricated by employing our proposed two-step reactive ion etching (RIE) processes. A novel bonding technique of diamond to Si at wafer level was also developed by using an inorganic-organic hybrid sol-gel film (MeSiO_3/2) as an adhesive layer to prepare a diamond/SOI wafer as the starting material. Moreover, we demonstrated the applicability of a fabricated diamond probe not only to AFM measurements but also to a tool for nanomachining.

Abstract: Silicon Nitride is largely used as the base material to manufacture cutting tools. Due to its low thermal expansion coefficient it is ideal candidate for CVD diamond deposition. In this work, we functionalized the surface of silicon nitride inserts (Si₃N₄) with a polymer (PDDA Poly (diallyldimethylamonium chloride - Mw 40000)) to promote seeding with nanodiamond particles. The seeding was performed in water slurry containing 4 nm diamond particles dispersed by PSS Poly (sodium4-styrenesulfonate) polymer. CVD diamond films, with high nucleation density, were deposited in a hot filament reactor. Film morphology was characterized by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Diamond film quality was determined by Raman Spectroscopy. CVD diamond film adherence was evaluated using Rockwell C indentation.

Abstract: Diamond coatings were prepared on mono-crystalline silicon by hot filament chemical vapor deposition (HFCVD). Hardness, elastic modulus and other mechanical properties of the diamond were analyzed by nanoindenter. The results showed that the process parameters such as chamber pressure, substrate temperature, methane volume ratio have a greater impact on the mechanical properties of the diamond coating. The micro-hardness and elastic modulus of the coating would both decrease with too high or too low substrate temperature, chamber pressure or volume ratio of methane. The results showed that when the substrate temperature is 750°C, champer pressure is 2.5kPa and methane volume ratio is 2%, the diamond coatings have high micro-hardness and elastic modulus.

Abstract: The growth of nano CVD diamond films on low index faces such as (111) face and (100) face under different proposed surface chemical reaction model was simulated by using Kinetic Monte Carlo (KMC) method from atomic scale. The results, for example the influence of deposition time t, substrate temperature T_s, and atomic hydrogen concentration [H] on the film deposition rate, surface roughness, and H embedded in the film under different processing conditions, were systematically analyzed and compared. And the adsorption of various species on {111}-oriented diamond cluster was preliminarily computed from electronic scale by Local Density Approximation (LDA) method to assist understanding the surface adsorption mechanism. It is indicated that the film morphology and quality obtained from atomic scale KMC simulation varies according to the chemical reaction models. And our initial electronic scale computation on {111}-oriented diamond cluster showed that single-carbon species can be adsorbed on the activated site more easily than double-carbon species and the former will result in a more stable state than the latter. In order to reveal the nano CVD diamond film growth mechanism, more work about various species adsorption on many different morphological CVD diamond surfaces is needed.