Showing posts from April, 2012

About semi conducting nanoparticles

  Nanoparticles of semi conducting materials have all three dimensions in the range of 1–20 nm and possess novel electronic, magnetic, catalytical, and optical properties. This is due to their large surface-to-volume ratio and their reduced size. As the diameter of the particle approaches the exciton Bohr diameter, the charge carriers become confined in three dimensions with zero degrees of freedom. As a result of the geometrical constraints, the electron feels the particle boundaries and responds to particle sizes by adjusting its energy. This phenomenon, known as the quantum size effect, causes the continuous band of the solid to split into discrete, quantized levels and the “bandgap” to increase. Preparation methods Traditional methods such as chemical vapor deposition and molecular beam epitaxy methods have been used but have limitations as they produce particles that are attached to a substrate or embedded in a matrix, thereby limiting their potential in applications. Colloidal a