Semiconductors, characteristic

Considerable interest in the sohd-state physics of sihcon carbide, that is, the relation between its semiconductor characteristics and crystal growth, has resulted from the expectation that SiC would be useflil as a high temperature-resistant semiconductor in devices such as point-contact diodes (148), rectifiers (149), and transistors (150,151) for use at temperatures above those where sihcon or germanium metals fail (see Semiconductors). 

Germanium was the semiconductor material used in the development of the transistor in the early 1950s. However, it exhibits high junction leakage current due to its narrow bandgap and is now largely replaced by silicon. It is a brittle metalloid element with semiconductor characteristics. The properties of germanium are summarized in Table 8.3.1 lP l... 

Figure 4.22 Schematic diagram of a field effect transistor. The silicon-silicon dioxide system exhibits good semiconductor characteristics for use in FETs. The free charge carrier concentration, and hence the conductivity, of silicon can be increased by doping with impurities such as boron. This results in p-type silicon, the p describing the presence of excess positive mobile charges present. Silicon can also be doped with other impurities to form n-type silicon with an excess of negative mobile charges.

It is thus evident that the characteristics of nanocarbons (conductivity, local structure, presence of defects and functional groups, morphology, etc.) are critical to determining the properties of the hybrid nanomaterial with the semiconductor. However, most of the literature studies put emphasis on the analysis of semiconductor characteristics, while often nanocarbons are only described in generic terms (CNT, for example). Yet, it is well known how the properties of nanocarbons can be considerably different from case to case (depending on details in preparation), even if the structure is formally the same (MWCNT, for example). 

Tellurium is a silver-white, brittle crystal with a metallic luster and has semiconductor characteristics. It is a metalloid that shares properties with both metals and nonmetals, and it has some properties similar to selenium and sulfur, located just above it in group 16 of the periodic table. 

The link between chemisorption and semiconductivity, as illustrated by this example, was first clearly perceived by Wagner and Hauffe (2) in 1938. Whereas the production of a semiconductor by chemisorption presents relatively little interest for our purpose, the reverse problem is currently receiving a great deal of attention. How is a given semiconductor going to behave in chemisorption Is it possible to relate semiconductor characteristics with catalytic properties and, if so, what are the properties of the semiconductor that have to be changed in order to modify and control catalytic activity ... 

Substrate Treatment. When the desired image is developed in the resist, the pattern created provides a template for substrate modification. The various chemical and physical modifications currently used can be classified into additive and subtractive treatments. Examples of additive treatments include the insertion of dopants (by either diffusion or ion implantation) to alter the semiconductor characteristics and metal deposition (followed by lift-off or electroplating) to complete a conduction network. In most cases, however, the substrate material is etched by a subtractive process. 

Fig. 7a. A glass cover plate protects the cell. Sunlight passes through the cover plate and the electrolyte to illuminate the semiconductor surface. Electrical current passes between the semiconductor and the counterelectrode through slots cut in the semiconductor. Characteristic features of this configuration are that no shadows are cast upon the semiconductor and that reaction products could be separated if a membrane were placed between the semiconductor and the counterelectrode.

ZnO exhibits many unusual properties including uniaxial piezoelectric response and n-type semiconductor characteristics. 

Since the rate and direction of light-induced charge transfer is governed by the relative position of occupied and unoccupied electronic states in the electrode and the electrolyte, this aspect of semiconductor characteristics of phthalocyanines is reviewed briefly. Knowledge of the position of the highest occupied... 

Polyaniline has been known for more than 100 years. Its semiconductor characteristics as well as possible application as battery electrodes were first... 

The insulator diamond has a band gap energy of 5.5 eV, while silicon has 1.1 meV and germanium 0.7 meV. Germanium loses its semiconductor characteristics at 100°C, compared to 200°C for sihcon. 

Beside their well-known extra-high mechanical properties, single-walled carbon nanotubes (SWNTs) offer either metallic or semiconductor characteristics based on the chiral structure of fullerene. They possess superior thermal and electrical properties so SWNTs are regarded as the most promising reinforcement material for the next generation of high performance structural and multifunctional composites, and evoke great interest in polymer based composites research. The SWNTs/polymer composites are theoretically predicted to have both exceptional mechanical and functional properties, which carbon fibers cannot offer [105]. 

The semiconductor characteristics of diamond and its device applications including recent progress have been reviewed in this chapter. 

Models of Mixed Ionic and Electronic Conducting (MIEC) Electrodes These specialised electrode models usually consider the MIEC electrode in combination with the electrolyte and focus on correlating performance with the semiconductor characteristics of the electrode (and sometimes electrolyte) [70-72]. Recent modelling of oxygen reduction and oxygen permeation at perovskite electrodes includes both MIEC effects and classical diffusion-type analysis [73-75]. 

---