Selective synthesis of compound semiconductor/oxide composite nanowires.

Semiconductor/oxide composite nanowires (NWs) were synthesized by molecular beam epitaxial growth and subsequent wet oxidation. Nonselective and selective oxidation conditions applied to the GaAs/AlGaAs core-shell NWs grown on silicon substrates produced GaOx/AlGaOx and GaAs/AlGaOx NWs, respectively. The oxidized amorphous AlGaOx shell produced cathodoluminescence over a wide spectral range encompassing ultraviolet and visible wavelengths, possibly sourced from molecular species related to oxygen. The wire core was buried in the oxides when the diameter of the oxide shell increased, forming a planar structure. These composites are expected to pave the way to future electrical and optical functions for NWs.