Semiconducting glasses

Amorphous selenium glasses, semiconductivity in, 12 587 Amorphous semiconductors, 22 127-141. See also Amorphous silicon (a-Si) amorphous silicon growth for,... 

Semiconductivity in oxide glasses involves polarons. An electron in a localized state distorts its surroundings to some extent, and this combination of the electron plus its distortion is called a polaron. As the electron moves, the distortion moves with it through the lattice. In oxide glasses the polarons are very localized, because of substantial electrostatic interactions between the electrons and the lattice. Conduction is assisted by electron-phonon coupling, ie, the lattice vibrations help transfer the charge carriers from one site to another. The polarons are said to "hop" between sites. 

Se-I 100, 185). These chalcogenide halide glasses belong to the so-called "semiconducting glasses that have attracted much attention in solid-state physics, because of their physical properties (see Section XII,B) they are, however, not treated in this review. 

Chain-transfer constants, 25 571t Chain-transfer rate constants, 19 832 Chain-transfer rates, 19 839 Chain transfer to solvent (CTS), 23 385 Chalcanthite, 7 772 Chalcogenide glasses, 12 575, 584 semiconductivity in, 12 587 Chalcogenides acidic, 12 190-191 gallium, 12 359 in photocatalysis, 19 75 plutonium, 19 691 zirconium, 26 641... 

All systems presented in this section show lasing only in the optical pumping mode. There is much interest in electrically pumped devices, but for molecular glasses the difficulties in achieving high excitation densities and low absorption due to charge carriers and electrodes have yet to be overcome. This problem and the related semiconducting polymer lasers that are based on the same principles will not be covered here, but are treated in recent reviews [214-216]. 

Optically transparent electrodes. In situ spectroelectrochemistry was discussed in the previous chapter. The most common materials for constructing optically transparent electrodes for use in such analyses are thin films of semiconducting oxide deposited on to glass. Such materials are readily available commercially. 

Sometimes, semiconductivity depends on the type of a structural phase that arises from synthesis. Thus, in the case of (TCNQ) Cu the semiconducting phase is thermodynamically disfavored. To prepare this semiconductor, Harris et al. (2005) proposed to perform the reduction of TCNQ in acetonitrile at glass-carbon, gold, or platinum electrode in the presence of Cu. This allows the electrocrystallization of sparingly soluble TCNQCu semiconducting phase to occur by a nucleation... 

Compound Semiconductors. The niobium-based superconducting compounds lead us naturally into another use for intermetallics—namely, semiconductors. This topic, too, was introduced earlier in this chapter (cf. Section 6.1.1.4 and 6.1.1.5), and we shall build upon those principles here to describe the semiconducting properties of compounds, ceramics, and glasses. The classification of intermetallics as ceramics... 

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