Single crystal diamond, applications

When a single crystal diamond (synthetic or natural) is the substrate, epitaxial growth occurs the growing diamond replicates the substrate crystal lattice and turns to single crystal film. The film thickness usually comes to a few microns however, films of 1 mm in thickness were reported. The diamond-coated area would achieve 10 cm in diameter by order for industrial applications, much larger areas (e.g. 40 by 60 cm) are covered. Samples destined for the electrochemical measurements used to have dimensions ca. 1 by 1 cm. 

Although the LPSSS method, invented by Roy s group in 1992, has not generated single crystal diamond films, it provides with useful information for diamond creation in metals. Indeed, the concept was already described in Section 9.2.1 for diamond heteroepitaxy on Ni. It seems that the LPSSS method will find practical applications in the fnture. It would thus be worthwhile to review the LPSSS method here. The LPSSS method using various carbon sources and metals (Mn, Fe, Co, Ni, Pt, Ag, Au, Cu) were published in Refs. [175, 391, 392, 412, 413], but only typical two techniques will be described below. 

Natural Type Ila single crystal diamond heatsinks have been used for the thermal management of microwave and laser diode devices for well over a decade [17,18]. The restriction in the size of available natural diamond has, however, limited the use of diamond to the heat management of small, discrete devices such as single junction laser diodes. The commercial availability of large CVD diamond plates has opened a host of new possible applications in which diamond can be used in the heat management of larger electronic and optoelectronic devices [1,77,78]. 

Single Crystal Diamond for Ultraprecision Machining Applications... 

The ability to deposit single-crystal diamond, or at least a material with a high degree of crystalline orientation and with properties equal to the high-purity single crystal material, would be an important factor in the development of CVD diamond in electronic, semiconductor, optical, and other applications. 

A CVD diamond coating is yet to be produced with the optical clarity of single-crystal diamond and, for that reason, CVD diamond has found little application so far in optics. Typically CVD diamond coatings are translucent. Some are nearly white, some have a black tinge. ... 

DLC is not as good an optical material as single crystal diamond but, as seen above, it has many advantages as a thin coating and is satisfactory in many applications. The following is a review of present and potential optical applications of DLC. 

By beginning with 12C methane, the diamonds formed have only 12C in them. These tiny diamonds may then be used as the carbon source to form large (5 mm) single crystals by growth from molten catalyst metal in a temperature gradient. The resulting nearly pure crystals have outstanding thermal conductivities suitable for special applications as windows and heat sinks (24). 

Two major classifications for diamond crystals are mono- or single crystalline and polycrystalline. The monocrystalline diamond particles tend to have more uniform surfaces and sharp edges. The abrasiveness of the monocrystalline diamond is mainly governed by its particle size. In the case of polycrystalline diamond, it is sometimes determined by the packing arrangement and the interaction of these single crystals that are related to friability [84]. Friability is defined as the readiness of a substance to crumble and form fine particles or fibers under the application of external pressures. 

In order to increase the intensity and focus of electrons, a field emission source may be used. This consists of a single crystal tungsten or LaBeClOO) wire that is sharpened to a tip diameter of ca. 100 nm — 1 j,m. For crystalline tungsten, the axis is suitably aligned with respect to the optical axis of the microscope. For example, a beam with a diameter < 5 nm is possible from alignment of the filament planes perpendicular to (310) and (111). In addition to W and LaBe, a number of other materials are proposed for field emission applications, such as silicon, single-walled nanotubes,and ultrananocrystalline diamond (UNCD) or Cu/Li alloy films deposited onto sharpened tips.t ... 

It was discovered by Sawabe and co-workers [10, 405] by DC plasma CVD that diamond grows heteroepitaxially on Ir(lOO). A single crystal Ir(lOO) film for a substrate was deposited on MgO(lOO) of 10-mm square by electron beam deposition at the substrate temperature of 750 °C, and then annealed in vacuum for 60 min at 950 °C. The Ir film thickness was 500 nm. The setup of the DC plasma CVD reactor that has the third electrode between the anode and the cathode for bias application has been shown in Figure 4.2. 

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