3. Nanostructured Chalcogenides

Nanoscale materials are currently being exploited as active components in a wide range of technological applications such as composite materials, chemical sensing, biomedicine, optoelectronics, and nanoelectronics. The term nano- refers to material structures which have a scale of about 1–100 nm. As the size of the nanoparticles (NPs) decreases and approaches the Bohr radii of atoms, the nanocrystals begin to exhibit quantum mechanical properties and are referred to as a quantum dots (QDs). At this size, its excitons are confined in all three spatial dimensions. The electronic properties of these materials are intermediate between those of bulk semiconductors and of discrete molecules. Advanced nanolithographic techniques such as electron-beam writing, X-ray lithography, proximal probe patterning, and near field optical lithography have demonstrated versatility for generation of a rich variety of nanostructures. However, these techniques can be limiting in terms of cost and throughput. Hence, relatively simpler methods such as vapor–liquid–solid (VLS) formation and chemical methods are being rapidly investigated for synthesis of materials at the nanoscale for different applications. Solution phase or colloidal nanocrystals are promising candidates in these fields, due to their ease of fabrication and processibility. Even more applications and new functional materials might emerge if nanocrystals could be synthesized in shapes of higher complexity than the ones produced by current methods (spheres, rods, disks). In this chapter we review the synthesis of chalcogen based materials at the nanoscale in one, two, and three dimensions using VLS and solution phase techniques.