Small bandgap semiconductors

If small bandgap semiconductors could be stabilized in water for much more prolonged time by polymer coating, it must lead to developments of efficient photochemical cell and water photolysis system. 

As for the photoexcitation center, dye sensitizers, small bandgap semiconductors or dye-sensitized large bandgap semiconductors are candidates... 

The shift of EB can partly be removed by illumination of the sample with white light (W Hal lamp, 40 mW/cm2) (Fig. 4). As the observed surface photovoltage is considerably smaller than the shift of EB due to adsorption the formation of an inversion layer on this small bandgap semiconductor has to be assumed. The... 

The recombination rate Rp has been discussed above there are two main routes [2] (a) direct VB/CB transition and (b) recombination via localised states within the bandgap. The first is important in small bandgap semiconductors, but its importance decreases with increasing energy. The second is likely to be the dominant process for higher bandgap materials since it facilitates energy transfer to the lattice. The trap equilibria have already... 

Figure 3.3 One-dimensionally confined quantum weU created by a thin small-bandgap semiconductor...

Transport and magnetic properties of complex TCNQ salts with symmetric and asymmetric bipyridine donas are presented. The salt with symmetric donor is a small bandgap semiconductor with large anisotropy in the conductivity, the susceptibility indicates strong electron correlations. The asymmetric donor leads to a material in which both the electric and magnetic properties can be discussed by electron localization due to disorder. 

In conclusion, with no disorder present, the interchain coupling leads to a CDW state, where electron correlations on neighbouring chains are correlated and the material is a highly anisotropic small bandgap semiconductor with electron correlation effects playing a decisive role. 

Gerischer73 and Nozik74 have stated that the formation of an inversion layer can also cause a shift of band edges. For small bandgap semiconductors, this effect may be more important. The formation of an inversion layer has been shown experimentally at several semiconductor/electrolyte interfaces.75-78... 

Here, there is no overlap between the band lineups of the materials. Type IIB structure are in fact special case of type II structure, where material B is either a small bandgap semiconductor or a semimetal. This results in little or no barrier for the holes in material A and the electrons in the material B. See Fig. 6c. The superlattices of InAs (Eg = 0.36 eV) and GaSb (Eg = 0.7 eV) are an examples of type III structure. 

Reductive Electropolymerization. Besides the oxidative anodic electropolymerization of the monomer, which is the most convenient and the most widely used method, polythiophene can also be prepared by a cathodic route involving the electroreduction of the complex Ni(2-bromo-5-thienyl)(PPh3)4Br in acetonitrile. This method, initially proposed for the synthesis of poly(p-phenylene) [374-376], has been extended to polythiophene [520]. The major drawback is that the polymer is produced in its neutral insulating form, which leads rapidly to a passivation of the electrode and limits the attainable film thickness to approximately 100 nm. On the other hand, this technique presents the advantage of being applicable to electrode materials subject to anodic corrosion such as small-bandgap semiconductors [521]. 

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