9. Nanometric Semiconductors

Reducing the size of materials -and semiconductors are no exception- to nanoscale dimensions, changes extremely their bulk properties. These semiconductors exhibit unique optoelectronic and magnetic properties and at a small size of about 20 nm or below, high surface area and quantum size effects characterize them. Recall, the so-called quantum size effect describes the physics of electron properties in solids with great reductions in particle size. This effect does not come into play by going from macro to micro dimensions. However, it becomes dominant when the nanometer size range is reached, particularly at the lower end of the nanoscale, affecting as indicated, optical, electrical, and magnetic behavior of materials. It is expected that the mechanical properties of the nanoscale materials -the subject of this book- also, will be much affected as compared to their bulk counterpart. Materials can be produced as nanoscale size in one dimension (for example, very thin surface coatings), in two dimensions (for example, nanowires and nanotubes) or in all three dimensions (for example, nanoparticles and quantum dots).