Porous semiconductors

Germanium-Based Porous Semiconductors from Molecular Zintl Anions... 

Scheme 1 Typical Zintl clusters (a) [Gcg], (b) [Nl3 (Ge9)2], (c) [Pt Pbi2], (d)[GegZn]° and (e) [Sn9Pt2] as building block candidates for the construction of porous semiconductors...

Starodub NF, Starodub VM (2002) Porous silicon some theoretical aspects and practical application as transducer for immune sensor. In Extended abstracts of the 3rd international conference porous semiconductors science and technology, Puerto de la Cruz, Tenerife, Spain, pp 155-157, 10-15 Mar 2002... 

Canham LT (1997) Porous semiconductors a tutorial review. Proc Mat Res Soc Symp 452 29-42... 

Cf are the resistance and capacitance due to the particulate semiconductor film R m and are the resistance and capacitance of the parts of the BLM which remained unaltered by the incorporation of the semiconductor particles Rsc and Csc are the space charge resistance and capacitance at the semiconductor particle-BLM interface and Rss and Css are the resistance and capacitance due to surface-state on the semiconductor particles in the BLM. Electrolytes short circuit the porous semiconductor particles (Rf = Rsol = 1.4 kO) such that their contribution, along with that due to the Helmholtz layer, can be neglected. This allows the simplification of the equivalent circuit to that shown in Fig. 108c. As seen, the working electrode is connected (via ions) to the semiconductor particulate film. 

The optical properties of porous silicon have given rise to renewed interest in the processes leading to pore formation and the relationship between the structure and characteristic properties of porous layers. Indeed, porous semiconductors may be considered a new class of materials, since pore formation is not limited to silicon and has been observed for a wide range of compound semiconductors. 

J.-N. Chazalviel, R. B. Wehrspohn, and F. Ozanam, Electrochemical preparation of porous semiconductors From phenomenology to understanding. Mater. Sci. Eng. B69-70, 1, 2000. 

Many speciahzed laboratory reactors and operating conditions have been used. Sinfelt has alternately passed reactants and inert materials through a tubular-flow reactor. This mode of operation is advantageous when the activity of the fixed bed of catalyst pellets changes with time. A system in which the reactants flow through a porous semiconductor catalyst, heated inductively, has been proposed for studying the kinetics of high-temperature (500 to 2000°C) reactions. An automated microreactor... 

Fig. 33 is a schematic illustration of a porous semiconductor electrode interpenetrated with a redox electrolyte. Two situations are shown the dark equilibrium situation and the situation under constant illumination from the electrolyte side (comparable illustrations for a bulk semiconductor/electrolyte interface are given in Figs. 4 and 5). In the dark at equilibrium, the electron Fermi-level in the porous network, Ep , is equal to the Fermi-level of the redox system Ep,redox = — Ueq) and independent of the spatial co-ordinate x normal to the substrate. If an electrolyte with a sufficiently positive redox potential is chosen, can be located in the middle of the gap, which means that the density of electrons in the nanostructured network is... 

Photocurrent generation is one of the most interesting direct applications of photosynthetic studies. The adsorption of sensitizers onto semiconductor surfaces has been found to be an efficient way to generate photocurrents and has been studied extensively. Ruthenium bipyridyl complexes, in particular, have been the focus of recent research [137-139]. In these cases, only the first layer of molecules, which is in direct contact with the surface, is active. A highly porous semiconductor material was therefore employed to compensate for the low level of absorption of the single molecular layer. Other varieties of chromophores, semiconductor materials, and electron carriers for totally solid systems have been the subjects of extensive studies. The present... 

An alternative route exists for the preparation of porous semiconductors. Many n-type single crystals, such as GaP, GaAs,... 

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