Group III-V compounds

Thermodynamic predictions of the solid-phase composition have been very successful for the growth by MOCVD of group III-V compound semiconductors (e.g., InAs Sb and GaAs SbJ even though the gas-phase reactions are far from equilibrium (88-91). The procedure is also useful for estimating solid-vapor distribution coefficients of group II-VI compound semiconductors (e.g., Cd Hg e and ZnSe SJ grown by MOCVD (92). In the analysis, the gas phase is considered to be an ideal mixture, that is... 

At present, primarily the binary compounds have been studied, and considerations of product volatility are the most significant driving force behind much of this research. The group III—V compounds are particularly difficult, because the group V elements form volatile halides, whereas group III halides, particularly the fluorides, tend to be involatile. As a result, F source plasmas, which have been the mainstay of silicon technology, are... 

Table 15.Representative studies up to 1985 on Group III-V compound semiconductors from a water photosplitting perspective."...

Much less work has appeared on AlGaAs alloys. A bipolar electrode configura tion of Alo.isGao.ssAs (Eg = 1.6 eV) and Si was used in conjunction with OER and HER co catalysts, RuCh and Pt, respectively, to drive water photosplitting at 18.3% conversion efficiency.209 Clearly, among all the photoelectrode materials discussed up till now, the Group III-V compounds, namely, InP and the alloyed materials, have yielded the most impressive results. 

At this stage, there is insufficient evidence to decide which, if either, of these models is correct, or indeed whether a unified explanation is possible. We should point out that Tu s model was derived principally for Si, whilst Spicer s proposals were based on work on Group III—V compounds, but it is quite evident that there is a common feature of high interface mobility. 

The impetus for this topic has been provided by the development of molecular beam epitaxy (MBE) as a viable thin film deposition process [ 111]. As a result, the approach has concentrated more on investigations of reaction kinetics than on electronic effects, since kinetic parameters are directly available from modulated molecular beam measurements (see Sect. 2.4.1). We will summarize here only the results for beams of As4 and As2 interacting with 100 GaAs surfaces, but closely similar behaviour is observed for other Group V elements and other Group III—V compound surfaces. The choice of tetramer and dimer beams is dictated by the evaporation behaviour of Group V elements in that elemental sources produce tetramers and Group III—V compound sources produce dimers. Monomeric species are not readily available. 

Broadening the range of elements used in sheet polymers further, one might even speculate about the possibility of forming group III-V compound sheet polymers such as (GaAsH2) . Attempts to form a CaGaAs Zintl phase have, however, failed also due to phase separation,so that the formation of such compound polymers, if stable at all, does not appear to be possible via the Zintl phase route. 

Vapor-Phase Epitaxy of Group III-V Compound Optoelectronic Devices... 

The compounds formed by the Group IIIA elements of the periodic table, Al, Ga and In, with the group VA elements, P, As and Sb, have the potential to be extremely important semiconductor materials. The attractiveness of Group III-V compounds as electronic materials lies in the variability of electrical properties among the different compounds and the fact that these properties are often superior to those found in Si. 

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