Core-shell GaAs-AlAs nanowires grown by MBE

The objective of this work was to achieve control over MBE growth of GaAs core-shell nanowires using the gold assisted VLS method, thereby facilitating formation of either pure Wurtzite (WZ) or pure Zinc Blende (ZB) wires. Growth of WZ type wires relies on initial nucleation of a thin (¿ 10 nm) GaAs wire which, based upon theoretical calculations, is expected to be free of SF. Preferential nucleation of pure ZB type wires required a respective reduction of the supersaturation, so as to simulate the conditions, which dominate the growth of epitaxy/bulk material. A shell composed of AlAs layer and a capping GaAs layer was applied in situ to both types of wires in order to form confined structures for optical and electronic applications.