Unique optical and electrical properties of silicon-containing heteronanocluster which has three dimensional superlattice structure

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The novel synthesis and the electrical and optical properties of Si and Ge nanoclusters which have nanometer sized core and organic side chains have been studied. Such clusters are soluble in common organic solvents due to the organic side chains and show semiconducting properties due to the Si and Ge lattices of the nanoclusters. The studies of the new materials designed from the organo-silicon and germanium nanoclusters using a basic unit. The quantum size effect of the organo-silicon and germanium nanoclusters and the formation of Si/Ge heterojunction between Si and Ge nanoclusters are investigated. After the formation of Si and Ge core dispersed in THF, an alkylbromide was added to substituted the SiMgCl and GeMgCl, respectively. The formation of Si-Si, Si-Ge, and Ge-Ge bonds by copolymerization were observed by Raman spectroscopy. By the time-resolved emission spectroscopy, significant quantum size effects were observed in the measurements of emission maxima and emission lifetimes. The organo-silicon and germanium cluster showed a broad emission bands in visible region. The origin of the emission band was discussed based on the time-resolved emission spectra and molecular orbital calculations. The distorted excited state formed around the branching point was assigned as the emission site and the origin the large stokes shift. The decay analysis suggests the energy migration in the Si/Ge nanocluster. The thin film of the organo-silicon and germanium clusters were prepared by spin-coating technique. By heat treatment, plasma irradiation, laser annealing, and so on, the organo-silicon and germanium cluster films can be converted to inorganic Si and Ge films, respectively. Such a technique provides the formation of c-Si, c-Ge, and c-Si/Ge films by coating.