Semi-conductor

In the above presentation of the band theory, the temperature was implicitly assumed to be 0 K. In case of an insulator, the effect of temperature is to promote the electrons of the valence band into the conduction band. These two energy bands are then neither totally filled nor totally empty respectively, and both contribute to conductivity. If conductivity becomes relatively significant (= lO -lO Q cm ), we refer to semi-conduction. Charge carriers are the electrons present in the conduction band, in concentration n, and also the electrons of the valence band. For the latter, their contribution with respect to the different physical properties, conductivity, specific heat, etc., is the same as positively charged particles called electron holes, with concentration p, the fraction of unoccupied states. The concentrations n and p are fixed by the following relationships  

nif are the effective masses of conduction electrons and electron holes (defined below). Or even  

2 At least for non-degenerated semi-conductors, i.e. when the double condition 

Intrinsic semi-conductivity Under effect of temperature only  

We refer to the intrinsic semi-conductivity. On closer examination of the values of Eg for a certain number of semi-conductor oxides or carbides (see Table 11.1) we can see that the concentrations of electrons and holes may be significant only at veiy high temperatures, unlike what we see for more traditional semi-conductors like silicon 

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The incorporation of minute amounts of arsenic in semi-conductors has been mentioned (p. 166). 

Zinc—bromine storage batteries (qv) are under development as load-leveling devices in electric utilities (64). Photovoltaic batteries have been made of selenium or boron doped with bromine. Graphite fibers and certain polymers can be made electrically conductive by being doped with bromine. Bromine is used in quartz—haUde light bulbs. Bromine is used to etch aluminum, copper, and semi-conductors. Bromine and its salts are known to recover gold and other precious metals from their ores. Bromine can be used to desulfurize fine coal (see Coal conversion processes). Table 5 shows estimates of the primary uses of bromine. 

C fi3 diamond films can be deposited on a wide range of substrates (metals, semi-conductors, insulators single crystals and polycrystalline solids, glassy and amorphous solids). Substrates can be abraded to facilitate nucleation of the diamond film. 

Wilson, A.H. (1939) Semi-conductors and Metals (Cambridge University Press, Cambridge). 

Hittinger, W., Metal Oxide Semi-Conductor Technology, Scientific American (August 1973)... 

Semi-conductors Ultra-high purity water Total organic carbon (TOC) reduction... 

The structure of the isomeric benzo-l,2,3-thiadiazole 11.30 is unknown, but the 1 1 adduct with AsFs (11.31) has been structurally characterized. The AsFs molecule is coordinated to the carbon-bonded nitrogen atom. Cycloocteno-l,2,3-selenadiazole is an effective source of selenium for the production of semi-conductors such as cadmium selenide." ... 

Semi-conductor solid solutions, 133 Silver, partial molar heat of solutions in tin, 133... 

Measurements of photoconductivity and of the Hall potential [367] are accurate and unambiguous methods of detecting electronic conduction in ionic solids. Kabanov [351] emphasizes, however, that the absence of such effects is not conclusive proof to the contrary. From measurements of thermal potential [368], it is possible to detect solid-solution formation, to distinguish between electronic and positive hole conductivity in semi-conductors and between interstitial and vacancy conductivity in ionic conductors. 

Wydeven [865] concludes that, in the presence of Co304 (6.8%), up to 60% of the reactant NaC103 decomposed in the solid state. During subsequent melting, there was an increase in reaction rate. The catalytic activity of the additive was ascribed to the electron accepting properties of the oxide (Co304 is a p-type semi-conductor). The apparent value of E increased from 120 to 200 kJ mole 1 between a = 0.05 and 0.5. 

The catalytic activity of doped nickel oxide on the solid state decomposition of CsN3 decreased [714] in the sequence NiO(l% Li) > NiO > NiO(l% Cr) > uncatalyzed reaction. While these results are in qualitative accordance with the assumption that the additive provided electron traps, further observations, showing that ZnO (an rc-type semi-conductor) inhibited the reaction and that CdO (also an rc-type semi-conductor) catalyzed the reaction, were not consistent with this explanation. It was noted, however, that both NiO and CdO could be reduced by the product caesium metal, whereas ZnO is not, and that the reaction with NiO yielded caesium oxide, which is identified as the active catalyst. Detailed kinetic data for these rate processes are not available but the pattern of behaviour described clearly demonstrates that the interface reactions were more complicated than had been anticipated. 

A.I. Gubanov, Quantum-Electronic Theory of Amorphous Semi-Conductors, Izd. Akad. Nauk SSSR, Moscow-Leningrad, 1963. 

Diffusion length in typical semi conductor electrodes, 492... 

Daikhin s analysis, 52, 53 double layer capacitance of solid at, 52 semi conductor, diffusion length, 492... 

Surface recombination, at semi conductors, 490 Surface reconstruction of gold, 83 and work of Kolb, 86 Surface tension and determination of the potential of zero charge, 32 Surface tension methods, and the potential of zero charge, 32 Surfaces,... 

Contact metallization and metallization of alumina in semi conductor applications. 

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