Study of nanoclusters provides insight into the mesoscopic regime between single molecules and bulk crystals. Nanoclusters exhibit strong quantum confinement and surface effects. Using nanoclusters as “building blocks” for novel materials offers an opportunity to understand how atomic structure can lead to physical and chemical properties of macroscopic materials. It is possible to produce Nan clusters with atomic arrangements that do not normally exist in nature, leading to novel optical and magnetic properties.
ZnO semiconductor sources
ZnO is a wide band gap semiconductor that has attracted tremendous interest as blue light emitting materials, gas sensors and transparent conductors in solar cells. Unlike other semiconductor compounds that contain cadmium, arsenic, or other environmental toxins, zinc and oxygen are “environment friendly” elements. In fact, ZnO is used as a dietary supplement in animal feed. The stability of excitons in ZnO results in a very high quantum efficiency at temperatures of 300 K and higher. It is an ideal material for room-temperature magneto-optic applications. At RT the band gap of ZnO is 3.4 eV, which is the UV region of the spectrum, making it an optically transparent semiconductor. Transparent ferromagnetic memory devices could be integrated with transparent transistors, providing “invisible”computing systems.
Nanocluster Sources
Various nanocluster Sources are: Supersonic nozzle source, Gas-aggregation source, Laser evaporation source and Pulse arc cluster ion source. Oxford Applied Research manufactures a nanocluster source based on the gas condensation technique and can be used to deposit a wide range of clustered materials for research and industrial applications. The NC200U is a nanocluster source designed for use in an ultra high vacuum environment. A magnetron discharge is used to generate the clusters.
The NC200U Nanocluster source can be used to produce metallic clusters with a high ionised content and very small clusters containing a few atoms up to large clusters.
Fe, Co and Ni clusters have the potential for high density magnetic storage and more recently as catalysts for the growth of carbon nanotubes. The NC200U source is capable of producing clusters of these magnetic materials with high deposition rates.
Si clusters have attracted considerable attention recently, not only because they luminesce, but also as potential building blocks in future nanodevices. The magnetron based NC200U Nan cluster source is capable of producing nanoclusters with a variety of sizes.
Compound clusters can be produced by adding other gases to the aggregation region. For example, TiN clusters can be formed by sputtering a Ti target with N2 as an aggregation gas.
The nanocluster sources can be used to deposit a wide range of clustered materials for applications raining from research into the fundamental properties of nanoscale structures, to industrial applications such as cataysis and highly adherent films. The nanocluster source is capable of producing beams of well defined nanocrystalline particles using the gas condensation method.