Optical properties of quantized semiconductor particles

Horst Weller
1996 Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences  
CdS nanoclusters ranging in diameters between 1 and 4 nm were prepared in aqueous solution using aliphatic mercaptoalcohols as ligands. The photon energies of the ls ls absorption and the respective oscillator strengths are in accordance with size quanti zation theory. Nonlinear optical properties are discussed in terms of the influence of trapped charge carriers on the excitonic transition. Onion-shell-like composite parti cles from CdS and HgS were prepared by successive substitution and
more » ... bstitution and reprecipitation processes. Particles with a core radius of 2 nm, a shell of up to 1 nm HgS followed by a final shell of up to 1.5 nm CdS were obtained. Electrons and holes were localized in the HgS shell, giving rise to excitonic fluorescence. Dense, yet randomly packed, nanoparticulate ZnO films were found to show reversible optical changes upon ca thodic polarization. Some cluster species crystallize in the form of macroscopic threedimensional superlattices, which were investigated by single-crystal X-ray analysis. The neutral C diyS^R S )^ clusters are covalently linked in the superlattice, the struc ture of which exhibits self-similarity to the interior structure of the clusters.
doi:10.1098/rsta.1996.0029 fatcat:2cvos2veqzhcngw3rjwpaa47ii