Multiple junction

Figure 11.6. Crossed nanowire p-n diode, (a) A typical SEM image of a crossed NW p-n diode, (b) Current-voltage (I-V) relation of the crossed p-n diode. Linear or nearly linear I-V behavior of the p-type and n-type NWs indicates good contact between NWs and metal electrodes. I-V curves across the junction show clear current rectification, (c) An SEM image of an NW p-n diode array, (d) I-V behavior for a 4(p) x l(n) multiple junction array. [Adapted from Ref. 57.]... 

Semiconductor - Metal Junctions Besides the semiconductor-liquid interface, electron-hole separation can be attained also when the couple is generated in the space charge layer of a homo/heterojunction or semiconductor-metal junction. The metal can also act as electrocatalyst (e.g., for reduction of 02, H+ or C02). The development of the proper structure, including arrays of multiple junctions in series to enhance photovoltages and efficiently harvest radiation [53] and/ or the inclusion of suitable electrocatalysts, is crucial. 

When several reactive phenomena co-exist at the same interface, it is necessary to express the equilibrium state by writing that the electrochemical Gibbs energies of reaction are zero for each phenomenon. In particular, keep in mind that when writing the equation for a combination of different equilibria in the form of a single overall equilibrium, this does not provide all the information necessary to give a thorough description of the interface equilibrium, as explained below in the example of multiple junctions. 

In this case, when the multiple junction reaches equilibrium, the iatter s junction voltage is not zero. 

Compared to homojunction stmcture amorphous silicon thin-film cells use a P-I-N hetrojunction stmcture, whereas cadmium telluride (CdTe) cells utilize a N-I-P arrangement. The overall picture embraces a three-layer sandwich with a middle intrinsic (/-type or undoped) layer between an N-t) e layer and a P-type layer (Fig. 3b). Multiple junction cells have... 

Since DNA can be involved in multiple junctions (Chapter 10.4), it should be employable as a nanoscale constructional material. High two-dimensional connectivity, for example, enables six-point star structures to be assembled [103] (Figure 11.50a). Various three-dimensional structures can also be built up as, for example. Figure 11.50b. Self-assembled bipyramids as well as DNA with 8 and 12 junctions have been reported [104,105], Nanotubes and cavity structures have been synthesised as well as DNA micelles [108], DNA molecular sieves and so forth [106-108]. 

There are two fundamental geometrical relations which hold for clusters of tree type with multiple junctions. For the total number of monomers in the cluster, the relation... 

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