ABSTRACT
Unlike elemental semiconductors, which are homopolar, compound semiconductors are partially ionic and their ionicity increases along the sequence of the IV–IV, III–V, II–VI, and I–VII compounds. Unlike elemental semiconductors, compound semiconductors are thermodynamically stable as non-stoichiometric, homogeneous phases, and present also a marked polytypism.
Ionicity, deviations from the stoichiometry, polytypism, and extended defects (twins and stacking faults) heavily influence their morphological and physico-chemical properties, with substantial differences among the different families of homologue compounds.
Various process chemistries have been developed to grow nanostructured compound semiconductors, and it is interesting to remark that nanowire formation in many cases does occur as a spontaneous, self-assisted process, provided the nucleation conditions have been properly selected.
Among the large number of compound semiconductors of possible interest at the nanoscale, the few which have been chosen do present the premises for technological applications, and their synthesis is of general interest for the main family.
Preparation and structural properties of SiC, GaAs, CdSe, CdTe, and CdS will be discussed in detail, with main emphasis on the influence of metal-assisted and self-assisted processes on the final synthesis products. As in the previous chapter, the detrimental effect of metal contamination will be taken into consideration, as well as the size-induced quantum confinement effects and lasing potentialities. It will be, eventually, demonstrated that twins and stacking faults induced by the presence of mixed phases in a single wire play a key role in their optoelectronic properties.
