NANO CRYSTALS

Semiconductor nanocrystals also known as quantum dots (QDs). These nanocrystals exhibit size quantization effects as an effect of their small size, resulting in a size dependence of their optical and electronic properties with respect to the bulk crystal. With decreasing particle size towards the bulk exciton Bohr radius, splitting of the energy bands will occur at the edges of the band structure. The splitting of the energy bands results in sharper energy transitions than for the bulk crystal comparable with atomic like transitions, with drastic changes in optical and electronic properties of the material... Figure 1. The effect of size on the band structure of a semiconductor crystal for four different size-ranges. The band structure of the bulk semiconductor crystal (R>>ab) with a continuous energy bands; a completely filled valance band (VB) and empty conduction band (CB), a quatum well, a quantum wire and quantum dot (R<... As consequence of the atomic like discrete energy..