QUANTUM CONFINEMENT IN CADMIUM SULFIDE SEMICONDUCTOR

Distinction of nanoparticles from bulk ones is not just a size in nm; it is a new phase quite different from bulk one. As the particulate size is reduced, the conduction band, valence band and the band gap in semiconductor undergo modification upon onset of nanophase. In particular case of quantum dots, the sizes in three dimensions are of few exciton radii, and exciton binding is greatly influenced. The binding energy of large excitons in semiconductor is taken as criterion for the onset of new phase, and calculations are reported using available data for quantum confinement of cadmium sulfide. It is observed that strong confinement region begins at a quantum dot size near 8 nm.