Structural and optical properties of a catalyst-free GaAs/AlGaAs core–shell nano/microwire grown on (1 1 1)Si substrate

Heterostructure in the catalyst-free GaAs nanowire grown on the Si substrate was studied for the application of optical devices in the next generation. We fabricated AlGaAs/GaAs/AlGaAs quantum well (QW) structure on the side facet of the catalyst-free GaAs nanowire grown by molecular beam epitaxy (MBE). The cathode luminescence (CL) measurement showed that the uniform GaAs quantum well was formed between AlGaAs shell layers. On the basis of this structure, we also grew the thick AlGaAs shell layers (∼700 nm) on GaAs nanowires, and observed whispering gallery mode (WGM) resonant in the thick AlGaAs hexagonal structure.