Group III-V semiconductor

Fig. 5. A gas manifold for the production of epitaxial layers of Group III—V semiconductors by OMCVD where I I represents a mass flow controller ...

As with the n-TiCte and n-SrTiCh counterparts discussed earlier in Section 6.2 of this Chapter (see also Ref. 407), luminescence probes have proven to be very useful for unraveling the mechanistic details of the cathodic processes both at n-type (e.g., n-GaAs)556 and p type (e.g., p InP)557,558 Group III V semiconductor surfaces. Finally, these semiconductors share another trend with those discussed earlier (metal chalcogenides) in that the majority of the studies since 1990 have been directed at solid solutions (alloys of GaP and InP, GaAs and InAs etc.). These newer studies will be addressed in Section 12 of this Chapter. 

In summary, Group III V semiconductors have several positive features that make them attractive for water photosplitting applications. The combination of high carrier mobility and an optimal band gap (particularly for many of the alloys, see below) coupled with reasonable photoelectrochemical stability for the p type materi al under HER conditions, should inspire continuing scrutiny of Group III V semi conductors. The control of surface chemistry is also particularly crucial to avoid problems with surface recombination. For example, the studies on p InP photoca thode surfaces have shown that a (controlled) ultra-thin interfacial oxide layer is critical for minimizing carrier recombination at the surface.66,199,201,554... 

In the case of alloys, we will consider, in turn, metal oxides, metal chalcogenides and, finally, Group III-V semiconductors. We have seen earlier (Sections 6.3 and 7) how non-metallic elements such as F, N and S can alloy with the metal oxide lattice, these species occupying anion sites within the host framework. The corresponding oxyfluoride, oxynitride and oxysulfide compounds are thus generated (Section 7). 

In recent years, the area of gallium arsenide has received much attention in relation to Group III/V semiconductors. Two reviews have appeared on the topic . 

Solid-Liquid Equilibrium in Ternary Group III-V Semiconductor Materials... 

As group III-V semiconductor QDs (e.g., InAs) can also be prepared via strain-induced growth mechanisms using molecular beam epitaxy (MBE) [13,14], there is an opportunity for a direct comparison of the properties of two QD systems coBoidal-grown nanocrystals versus MBE-grown dots [15]. 

This section first provides a general discussion of the synthetic strategy employed for group III-V semiconductor nanocrystals, followed by a description of the synthesis of InAs nanocrystals as a prototypical example. The characterization of the particles produced, using a variety of methods, is briefly reviewed, after which details are provided of the synthesis of core-shell nanocrystals with III-V semiconductor cores, focusing particularly on InAs cores. 

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