Semiconductor nanoclusters quantum size effects

Theoretical calculations have been extended to study the shape dependence of the quantum size effect [48], The effect of covering semiconductor nanoclusters with another semiconductor (heterostructure) was also examined [49]. All of these calculations are based on effective mass approximation. 

Phase-separated metal-containing block co-polymers formed by ROMP offer interesting possibilities for the controlled formation of semiconductor and metal nanoclusters, which are of intense interest as a result of their size-dependent electronic and optical properties, as well as their catalytic behavior. Zinc-containing block co-polymers generated by ROMP have been shown to form ZnS nanoclusters within the phase-separated organozinc domains upon treatment with gaseous The cluster sizes generated were up to 30 A and their small size led to quantum size effects. For example,... 

Another method was also employed to construct the multilayers of the alkylthiol SAMs-covered nanoclusters on the electrode surface [27-30, 110, 111]. Multilayers of the semiconductor nanoclusters covered with the alkylthiol SAMs, whose terminated groups are the charged groups, can be constructed on the basis of an electrostatic interaction (Fig. 9). Relatively large and stable photocurrents were observed at this electrode and photoelectro-chemical properties of the semiconductor nanoclusters were discussed on the basis of quantum size effect [109,110]. 

Nanostructured clusters of semiconductors and metals, which differ from the corresponding bulk material due to surface, shape, and quantum size effects, have been designed to possess unique properties due to electron confinement. The unique properties of nanosized metal particles can be utilized in a broad range of fields, from catalysis to optical filters as well as nonlinear optical devices. To understand how nanoclusters can be combined with dendrimers, first let s summarize general properties of dendrimers. 

During the past decade, a new focus has developed. It was found that semiconductor particles can be made so small, typically into the nanometer size regime, that a quantum confinement effect occurs [6-15]. Particles of this size are often referred to as nanoclusters, nanoparticles, quantum dots, or Q-particles. The structures of these nanometer-sized semiconductor clusters are usually similar to those of the bulk crystals, yet their properties are remarkably different. With the proper surface-capping agents, clusters of varying sizes can be isolated as powders and redissolved into various organic solvents just like molecules. The availability of this new class of materials allows us to study the transition of a material from molecule to bulk solid, as well as its various properties and applications. 

---