Electrical properties silicon carbide

Polysilanes can be regarded as one-dimensional analogues to elemental silicon, on which nearly all of modern electronics is based. They have enormous potential for technological uses [1-3]. Nonlinear optical and semiconductive properties, such as high hole mobility, photoconductivity, and electrical conductivity, have been investigated in some detail. However, their most important commercial use, at present, is as precursors to silicon carbide ceramics, an application which takes no advantage of their electronic properties. 

Electrical Properties. The electrical properties of silicon carbide are highly sensitive to purity, density, and even to the electrical and thermal... 

NISTCERAM National Institute of Standards and Techology Gas Research Institute, Ceramics Division mechanical, physical, electrical, thermal, corrosive, and oxidation properties for alumina nitride, beryllia, boron nitride, silicon carbide, silicon nitride, and zirconia... 

Silicon nitride is prized for its hardness (9 out of 10 on the Mohr scale), its wear resistance, and its mechanical strength at elevated temperatures. It melts and dissociates into the elements at 1,900 °C, and has a maximum use temperature near 1,800 °C in the absence of oxygen and near 1,500 °C under oxidizing conditions.41 It also has a relatively low density (3.185 g/cm3). Unlike silicon carbide, silicon nitride is an electrical insulator. The bulk material has a relatively good stability to aggressive chemicals. This combination of properties underlies its uses in internal combustion engines and jet engines. 

The preparation, manufacture, and reactions of SiC have been discussed in detail in Gmelin, as have the electrical, mechanical, and other properties of both crystalline and amorphous of SiC. Silicon carbide results from the pyrolysis of a wide range of materials containing both silicon and carbon but it is manufactured on a large scale by the reduction of quartz in the presence of an excess of carbon (in the form of anthracite or coke), (Scheme 60), and more recently by the pyrolysis of polysilanes or polycarbosUanes (for a review, see Reference 291). Although it has a simple empirical formula, silicon carbide exists in at least 70 different crystalline forms based on either the hexagonal wurtzite (ZnS) structme a-SiC, or the cubic diamond (zinc blende) structme /3-SiC. The structmes differ in the way that the layers of atoms are stacked, with Si being fom-coordinate in all cases. 

Silicon carbide, SiC (i), and silicon nitride, Si3N4 (2), have been known for some time. Their properties, especially their high thermal and chemical stability, their hardness, and their high strength, have led to useful applications for both of these materials. The conventional methods for the preparation of SiC and SiaN4, the high-temperature reaction of fine-grade sand and coke (with additions of sawdust and NaCl) in an electric furnace (the... 

Mechanical and electrical properties of multilayer composites of silicon carbide... 

A.O. Konstantinov, C.I. Harris and E. Janzen, Electrical properties and formation mechanism of porous silicon carbide, Appl. Phys. Lett., 65, 2699-2701 (1994). 

Thermal oxidation of the two most common forms of single-crystal silicon carbide with potential for semiconductor electronics applications is discussed 3C-SiC formed by heteroepitaxial growth by chemical vapour deposition on silicon, and 6H-SiC wafers grown in bulk by vacuum sublimation or the Lely method. SiC is also an important ceramic ana abrasive that exists in many different forms. Its oxidation has been studied under a wide variety of conditions. Thermal oxidation of SiC for semiconductor electronic applications is discussed in the following section. Insulating layers on SiC, other than thermal oxide, are discussed in Section C, and the electrical properties of the thermal oxide and metal-oxide-semiconductor capacitors formed on SiC are discussed in Section D. 

Various electrical and optical properties that have been measured for the wet thermal oxide on silicon carbide are summarised in TABLE 3. In general, no systematic variation of any of the oxide properties has been reported with oxide growth temperature in the range of 1000 to 1250°C. However, oxide grown with a wet process has been shown to have lower oxide charges than oxide grown in dry oxygen. Variations in the measured electrical properties... 

TABLE 3 Electrical and optical properties of the thermal oxide on silicon carbide at room temperature from... 

It is highly probable that the metal contamination strongly affects the electrical properties of silicon carbide crystals and reduces the carrier lifetimes, as in other semiconductors. Unfortunately, no detailed studies of this effect have been reported thus far. 

The extraordinary mechanical, thermal and electrical properties of carbon nanotubes (CNT) have prompted intense research into a wide range of applications in structural materials, electronics, and chemical processing.Attempts have been made to develop advanced engineering materials with improved or novel properties through the incorporation of carbon nanotubes in selected matrices (polymers, metals and ceramics). But the use of carbon nanotubes to reinforce ceramic composites has not been very successful. So far, only modest improvements of properties were reported in CNTs reinforced silicon carbide and silicon nitride matrix composites, while a noticeable increase of the fracture toughness and of electrical conductivity has been achieved in CNTs reinforced alumina matrix composites. ... 

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