Charles Lieber and colleagues at Harvard University in collaboration with Nanosys Inc are creating single-crystal nanowires from just about any semiconducting material. When combined in arrays and multilayers, the technique promises to create complex nanosystems.
The key to the process is using a nanocluster that is the same diameter as required for the wire. A liquid of the catalyst and the materials for the nanowire is used to allow the nanowire to grow continuously. For example, if a gallium-nitride nanowire is required, an iron nanocluster is used as it will selectively dissolve both gallium and nitrogen. Blasting particles from a substrate with a laser makes the catalytic nanoclusters. Changing the gas pressures in the blasting chamber alters sizes of the nanoclusters.
Nanosys have refined this process and now has a process for producing nanowires from all known semiconductors as well as ferroelectric and piezoelectric materials.