Diamond film electrically insulating

In addition to silicon and metals, a third important element being deposited as thin films is diamond (Celii and Butler, 1991 May, 2000). For many years, diamonds were synthesized by a high pressure/high temperature technique that produced bulk diamonds. More recently, the interest in diamonds has expanded to thin films. Diamond has a slew of properties that make it a desired material in thin-film form hardness, thermal conductivity, optical transparency, chemical resistance, electrical insulation, and susceptibility to doping. Thin film diamond is prepared using chemical vapor deposition, and we examine the process in some detail as a prototypical chemical vapor example. Despite its importance and the intensity of research focused on diamond chemical vapor deposition, there remains uncertainty about the exact mechanism. 

Single pulse, shock tube decomposition of acetic acid in argon inv olves the same pair of homogeneous, molecular first-order reactions as thermolysis (19). Platinum on grapliite catalyzes the decomposition at 500—800 K at low pressures (20). Ketene, methane, carbon oxides, and a variety of minor products are obtained. Photochemical decomposition yields methane and carbon dioxide and a number of free radicals, wliich have complicated pathways (21). Electron impact and gamma rays appear to generate these same products (22). Electron cyclotron resonance plasma made from acetic acid deposits a diamond [7782-40-3] film on suitable surfaces (23). The film, having a polycrystalline stmcture, is a useful electrical insulator (24) and widespread industrial exploitation of diamond films appears to be on the horizon (25). 

So far there have been only a few reports concerning the chemical modification of diamond, either insulating or electrically conducting diamond films that would potentially be useful as electrodes. Smentkowski and Yates reported on a facile approach for modifying the hydrogen-... 

Another application for diamond films depends on the possibility of producing the material for microelectronic components by building up layers of carbon atoms on a diamond film. Although diamond is an electrical insulator, like silicon and other materials, it becomes a conductor when small quantities of other substances, such as boron, are added to it. We say that the diamond has been doped and behaves as a semiconductor. (We will discuss semiconductors in Section 13.5.) In principle, diamond could supplant silicon as the material for constructing microelectronics devices, and theoretically these devices would be much faster than ones constructed from silicon. 

In Nature the diamond structure isn t transfer electrons thus is the electrical insulator material. However a technique by modifieation diamond films with boron-doped can increase the electron transfer this characteristie electrical of hybrid can be compared to semiconductors. Without used any pretreatment and a wide potential window (approaching 3 V) including characteristics good electrochemical reactivity, mechanical hardness, and lower adsorption on surface by contamination, the diamond electrodes are highly useful for electrochemical measurements [16]. 

Cubic boron nitride (cBN) is a very promising material that, after diamond, displays the highest hardness, excellent thermal conductivity, and important characteristic properties such as high electrical insulation and chemical and thermal stability. The cBN film can be deposited on a cemented carbide insert using activated reactive evaporation with a gas activation nozzle. Figure 20 shows the relation between the micro Vickers hardness (10 g load) of a BN film and its... 

The next point to realize is that the best emitter is a metal. Many forms of carbon initially studied are semiconductors or even insulators, including nanodiamond [8-11] and diamond-like carbon (DLC) [12-13,4]. Combine this with local field enhancement means that there is never uniform emission from a flat carbon surface, it emits from local regions of field enhancement, such as grain boundaries [8-11] or conductive tracks burnt across the film in a forming process akin to electrical breakdown [13]. Any conductive track is near-metallic and is able to form an internal tip, which provides the field enhancement within the solid state [4]. Figure 13.2 shows the equipoten-tials around an internal tip due to grain boundaries or tracks inside a less conductive region. 

---