Multi-Quantum Structures of GaAs/AlGaAs Free-Standing Nanowires

Free-standing semiconductor nanowires are promising for future nano-scale devices. We have investigated the growth and photoluminescence characteristics of AlGaAs-capped nanowires containing multi-quantum structures. Using small Au particles of around 20-nm diameter, we were able to form many columnar-like GaAs nanostructures in capped wire structures by means of vapor–liquid–solid growth for the wire cores and metalorganic vapor phase epitaxy for the capping. In order to investigate photoluminescence characteristics, we performed scanning near-field optical microspectrometer measurements at about 20 K. Many sharp luminescence peaks were observed around 700 nm. By mapping each peak, we could obtain some wire images. We found one wire had several luminescence peaks, which originated from localized excitons in the one-dimensional potential.