Surface Of Synthetic Diamond Research Articles

Micropatterning of synthetic diamond by metal contact etching with Ti powder

Due to the high hardness and chemical stability of diamond, micropatterning of diamond surfaces is a manufacturing challenge that limits the wide application of diamond. In this paper, uniformly distributed micropatterns were produced on the surface of synthetic diamond by metal contact etching of spherical Ti powder. The effects of spherical Ti powder particle size and etching temperature on the size and depth of the micropatterns were investigated. The results showed that the proportion of the patterned area on the diamond surface decreased with the particle size increase of spherical Ti powder. However, the size and depth of the micropatterns increased. In addition, both of the pattern area proportion of the diamond surface and the size and depth of the micropatterns increased with the rise of etching temperature. Importantly, diamond etching was achieved using Ti powder without appearance of graphitization of the diamond. This work is of significance for the customization of micropatterns on diamond surface and can further expand the application of diamond.

Dependence of Synthetic Diamond Wear Rate on Lattice Orientation at Traditional Mechanical Treatment

The results of comparative studies of the rate of mechanical polishing of the surface of synthetic diamond in various directions and different crystallographic surface orientations are presented. A free abrasive on a cast-iron disk is used for polishing. A method is proposed for numerical simulation of the polishing of an arbitrarily oriented diamond surface, based on an estimation of changes in the internal energy of the diamond crystal lattice under the action of the abrasive. The method enables determination of the direction of polishing, which ensures the maximum processing rate of a diamond surface of any crystallographic orientation. The validity of the proposed method is confirmed experimentally.

Engineering shallow spins in diamond with nitrogen delta-doping

We demonstrate nanometer-precision depth control of nitrogen-vacancy (NV) center creation near the surface of synthetic diamond using an in situ nitrogen delta-doping technique during plasma-enhanced chemical vapor deposition. Despite their proximity to the surface, doped NV centers with depths (d) ranging from 5 - 100 nm display long spin coherence times, T2 > 100 \mus at d = 5 nm and T2 > 600 \mus at d \geq 50 nm. The consistently long spin coherence observed in such shallow NV centers enables applications such as atomic-scale external spin sensing and hybrid quantum architectures.

Heat-Transfer Resistance at Solid–Liquid Interfaces: A Tool for the Detection of Single-Nucleotide Polymorphisms in DNA

In this article, we report on the heat-transfer resistance at interfaces as a novel, denaturation-based method to detect single-nucleotide polymorphisms in DNA. We observed that a molecular brush of double-stranded DNA grafted onto synthetic diamond surfaces does not notably affect the heat-transfer resistance at the solid-to-liquid interface. In contrast to this, molecular brushes of single-stranded DNA cause, surprisingly, a substantially higher heat-transfer resistance and behave like a thermally insulating layer. This effect can be utilized to identify ds-DNA melting temperatures via the switching from low- to high heat-transfer resistance. The melting temperatures identified with this method for different DNA duplexes (29 base pairs without and with built-in mutations) correlate nicely with data calculated by modeling. The method is fast, label-free (without the need for fluorescent or radioactive markers), allows for repetitive measurements, and can also be extended toward array formats. Reference measurements by confocal fluorescence microscopy and impedance spectroscopy confirm that the switching of heat-transfer resistance upon denaturation is indeed related to the thermal on-chip denaturation of DNA.

Surface Characteristics of Ni-Diamond Composite Powders by Electroless Plating Method

Ni-diamond composite powders with nickel layer of round-top type on the surface of synthetic diamond (140/170 mesh) were coated with semi-batch reactor by an electroless plating method (EN). The effect of nickel concentration and feeding rate of reductant, temperature, reaction time, and stirring speed on the weight percentage of deposited Ni and morphology, mean particle size, and specific surface area of the composite powders were investigated by AAS, FE-SEM, PSA and BET. The weight percentage of Ni in the composite powder increased with time and temperature but decreased with stirring speed, and the weight percentage was 55% at 150 min., 200 rpm and 70oC.

무전해 니켈 도금법으로 제조된 니켈-다이아몬드 복합분체의 특성

Ni-diamond composite powders with nickel layer of round-top type on the surface of synthetic diamond (140/170 mesh) were prepared by the electroless plating method (EN) with semi-batch reactor. The effects of nickel concentration, feeding rates of reductant, temperature, reaction time and stirring speeds on the weight percentage and morphology of deposited Ni, mean particle size and specific surface area of the composite powders were investigated by Atomic Adsortion Spectrometer, SEM-EDX, PSA and BET. It was found that nucleated Ni-P islands, acted as catalytic sites for further deposition and grown into these relatively thick layers with nodule-type on the surface of diamond by a lateral growth mechanism. The weight percentage of Ni in the composite powder increased with reaction time, feeding rate of reductant and temperature, but decreased with stirring speed. The weight percentage of Ni in Ni-diamond composite powder was 55% at 150 min., 200 rpm and 7<TEX>$0^{\circ}C$</TEX> .

Oxidative etching of cleaved synthetic diamond {1 1 1} surfaces

In this study, three commonly used methods for oxidative etching of diamond {1 1 1} faces are compared: gas phase etching using `dry' oxygen, gas phase etching using an oxygen/water vapour mixture and liquid etching in molten potassium nitrate. The synthetic diamond surfaces are prepared by cleavage. The morphology of the surfaces is studied using atomic force microscopy and the kinetics of the reactions is determined by measuring the decrease in thickness of the diamond. The atomic arrangement of the {1 1 1} surfaces etched in oxygen/water is studied using surface X-ray diffraction. Upon dry oxygen etching, the {1 1 1} faces are roughened and become morphologically unstable. This observation conflicts with standard theory, which predicts {1 1 1} to be a stable F-face that should etch via a layer mechanism. A possible explanation for this is chemical roughening. The addition of water vapour to the oxygen has a dramatic effect on the etching mechanism of the {1 1 1} faces. Now etching proceeds via a layer mechanism involving monoatomic steps. Shallow etch pits are formed, of which the slope increases for increasing etching temperature. Surface X-ray diffraction experiments show that the surface is –OH terminated. For potassium nitrate etching, the {1 1 1} face etches also via a layer mechanism and triangular etch pits with rounded corners are formed, having point or flat bottoms. This etching technique appears to be the best method to reveal different types of defects ending on diamond {1 1 1} surfaces.

Nanoindentation of diamond, graphite and fullerene films

The recently developed method of nanoindentation is applied to various forms of carbon materials with different mechanical properties, namely diamond, graphite and fullerite films. A diamond indenter was used and its actual shape determined by scanning force microscopy with a calibration grid. Nanoindentation performed on different surfaces of synthetic diamond turned out to be completely elastic with no plastic contributions. From the slope of the force–depth curve the Young's modulus as well as the hardness were obtained reflecting a very large hardness of 95 GPa and 117 GPa for the {100} and {111} crystal surfaces, respectively. Investigation of a layered material such as highly oriented pyrolytic graphite again showed elastic deformation for small indentation depths but as the load increased, the induced stress became sufficient to break the layers after which again an elastic deformation occurred. The Young’s modulus was calculated to be 10.5 GPa for indentation in a direction perpendicular to the layers. Plastic deformation of a thin fullerite film during the indentation process takes place in the softer material of a molecular crystalline solid formed by C60 molecules. The hardness values of 0.24 GPa and 0.21 GPa for these films grown by layer epitaxy and island growth on mica and glass, respectively, vary with the morphology of the C60 films. In addition to the experimental work, molecular dynamics simulations of the indentation process have been performed to see how the tip–crystal interaction turns into an elastic deformation of atomic layers, the creation of defects and nanocracks. The simulations are performed for both graphite and diamond but, because of computing power limitations, for indentation depths an order of magnitude smaller than the experiment and over indentation times several orders of magnitude smaller. The simulations capture the main experimental features of the nanoindentation process showing the elastic deformation that takes place in both materials. However, if the speed of indentation is increased, the simulations indicate that permanent displacements of atoms are possible and permanent deformation of the material takes place.

Frictional characteristics of diamond sliding on as-grown surfaces of large GEM quality single crystal synthetic diamond

Sliding friction measurements are reported on {{111}} and {{001}} surfaces of synthetic diamonds in the as-grown condition. The measurements were done in ambient air, and the lowest friction coefficient observed was 0.004 on {{111}} faces in 〈112〉 directions. The friction coefficient varies with sliding direction, as has been previously reported. The frictional energy loss is primarily associated with adhesion. Polished surfaces of natural diamonds were also measured for comparison. Ultra-fine polishing of a surface reduces the friction compared with a conventional polish. Synthetic diamonds with different dopants were investigated, but no correlation between friction and dopant was found.

Electron spectroscopy of the surface of diamond and cubic boron nitride

The paper presents an AES investigation of the modification of the surface of synthetic diamond and cubic boron nitride (BN c) by electron beams and argon and oxygen ion beams in the energy interval from 2 to 10 keV.

Reflection electron microscopy of as-grown diamond surfaces

It has been found that the abrasion of diamond-on-diamond depends on the crystal orientation. For a {100} face, the friction coefficient for sliding along &lt;011&gt; is much higher than that along &lt;001&gt;. For a {111} face, the abrasion along &lt;11&gt; is different from that in the reverse direction &lt;&gt;. To interpret these effects, a microcleavage mechanism was proposed in which the {100} and {111} surfaces were assumed to be composed of square-based pyramids and trigonal protrusions, respectively. Reflection electron microscopy (REM) has been applied to image the microstructures of these diamond surfaces.{111} surfaces of synthetic diamond:The synthetic diamonds used in this study were obtained from the De Beers Company. They are in the as-grown condition with grain sizes of 0.5-1 mm without chemical treatment or mechanical polishing. By selecting a strong reflected beam in the reflection high-energy electron diffraction (RHEED) pattern, the dark-field REM image of the surface is formed (Fig. 1).

The morphology changes in diamond synthesized by hot-filament chemical vapor deposition

Hot-filament-assisted chemical vapor deposition has been used to study the growth morphology of synthetic diamond deposited on silicon substrate in a dilute (1 vol %) CH3COCH3/H2 at high substrate temperature (about 777 °C). Scanning electron microscope pictures of the diamond particles show that the surfaces of synthetic diamond consist of rough-octahedral (111) faces and smooth-cubic (100) faces, which is cubo-octahedron. And also the (110) facets on the octahedral face are observed. The relative growth rate of (111) faces to that of (100) faces in the cubo-octahedron is double that derived from the calculated specific surface energy. So the apparent growth rate of the octahedral face must be explained by the growths of two constituent crystallographic planes of (100) and (110). The observed roughness of (111) faces arises from the competing growths of (100) and (110) planes. The (110) faces separate the (111) faces into three (110) planes. For the study of diamond crystal growth during deposition, it is suggested that the growth mechanism of cubo-octahedral diamond is the competing growths of (100) and (110) crystallographic planes.

A STUDY OF SYNTHETIC DIAMOND SURFACE USING REFLECTION ELECTRON MICROSCOPY

The surface of synthetic diamond have been observed employing reflection electron microscopy with both TBM and STEM instrument. It is found that there are slip steps of screw dislocations, growth steps and microcrystals on the surface. The result shows that the surface of sythetie diamonds is characteristic of crystallization from solution.