Semiconductor comparison with metal

The specificity of chemical bonds and defect structure of semiconductors in comparison with metals determines the necessity of further development of the concept of a nonstoichiometric phase. Semiconductor compounds with one-sided wide homogeneity region represent a special group of nonstoichiometric phases. We discussed the specificity of properties of such phases using SnTe as an example. The conducted studies yielded the following results. 

A number of zinc selenium complexes have now been characterized, with particular interest in the formation of zinc selenide semiconductors and quantum dots. In many cases analogous structures to those observed with thiol or thiolates are recorded. 77Se NMR is frequently used in characterization, and comparison with the sulfur equivalent is relevant. Zinc selenium compounds are of particular interest as precursors for metal/selenide materials and their relevance as models for selenocysteine-containing metalloproteins. 

Yu HZ, Liu YJ (2003) Alkyl monolayer passivated metal-semiconductor diodes 2 Comparison with native silicon oxide. ChemPhysChem 4 335-342... 

After some general remarks on the relations between semiconductor properties and their use as photocatalysts, this text will first deal with oxidations of organic compounds.The interactions of illuminated semiconductors with gaseous C>2 (and, for comparison, with gaseous NO) will be then presented, whereas the last part will consider metal/semiconductor photocatalysts and the organic reactions they allow. In this presentation, the results of this laboratory will be highlighted. 

In a similar manner, during the process of the existing metal particles growth and the deposition of new species using cathodically biased electrode in a solution of metal ions, the growing metal phase will be also localized at the sites of the surface exposure of the continuous donor centers. The reason for this is that namely these sites possess substantially enhanced electrocatalytic activity in comparison with the stoichiometric oxide surface and exhibit the properties of current channels non-restricted by the Schottky barrier at the interface with the electrolyte. Actually, a peculiar decoration of the sites of donor centers accumulation and donor clusters localization by the metal nanoparticles takes place in the dark processes of metal particle deposition onto the surface of the chemically inert wide-band-gap oxides. The increased electrocatalytic activity of the wide-band-gap semiconductor electrodes resulted from the deposition of metal nanoparticles on their surface may be also regarded as a kind of such decoration . 

The foregoing discussion strictly refers to semiconductors in single-crystal form. Amorphous and polycrystalline counterparts present other complications caused by the presence of defects, trap states, grain boundaries and the like. For this reason, we orient the subsequent discussion mainly toward single crystals, although comparisons with the less ideal cases are made where appropriate. The distinction between metal and semiconductor electrodes also becomes important when we consider the electrostatics across the corresponding solid-liquid interfaces this is done next. 

There are many reviews of the vast literature on CPs, including 15 books compilations in various encyclopedias and an excellent overview by Kanatzidis. They cover all aspects of the theory, energy band structure, chain structure, morphology, comparison of conductivities with metals, semiconductors and insulators, doping, synthesis and characterization, electrochemistry, processing, and potential... 

First, noble metal diffusion in DIP and Pc were carried out. As Ag diffusion in polymers is well studied and understood [12, 13, 15-17, 32, 33], depth profiles for Ag diffusion in Pc and DIP were obtained. Comparison with the depth profiles of polymers will help to further the understanding of the nature of noble metals in these organic semiconductors. 

The data calculated from first-principles and their comparison with experimental results for metals, semiconductors, oxides, and intermetaUic compounds are presented in Table 9.1. 

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