ABSTRACT
The aim of this chapter is to look at the relationships between the optical properties of semiconductor nanostructures and their local core-and-shell size, structure, morphology, chemical composition, and defectivity, in view of a better understanding of the effect of growth conditions on their properties.
Given the large amount of literature information available on silicon nanocrystals, films, and nanowires, their spectroscopic properties will be discussed in full detail, with some practical phenomenological and theoretical conclusions, which will concern also size-dependent quantum confinement effects, significantly blue-shifting their IR emission toward the visible, and solvent effects.
The optical properties of a variety of II–IV, III–V, and II–VI semiconductor compounds nanowires will be, as well, deeply considered, with major emphasis on the role of polymorphism and of structural defects (twins and stacking faults) in SiC, GaAs and CdTe, CdSe, and CdS.
The lasing potential of semiconductor nanowires will be eventually also discussed, and the origin of lasing effects due to their nanocrystalline morphology or to the presence of wire segmentation associated with twin defects will be put in evidence for several semiconductor nanostructures.
Deep level transient spectroscopy (DLTS), optical absorption, photoluminescence and surface photovoltage spectroscopies, and optically detected magnetic resonance, associated with SEM, TEM, and HRTEM measurements, are mostly used for the investigation of the correlation of the optoelectronic properties of nanostructured semiconductors with their morphology and defectivity and to infer from them on the nature of the optically active defects present in nanostructured matter.
