Investigation of the Electronic Structure of GaAs/AlGaAs Core Multi-Shell Nanowires

We use photoluminescence and PL excitation spectroscopy to study the electronic structure of GaAs/Al$_{x}$Ga$_{x}$As core multi-shell NWs. Using Au-catalyst assisted MOCVD, a 10 nm GaAs quantum well tube (QWT) with AlGaAs barriers is formed surrounding a central $\sim $50 nm GaAs core. With resonant excitation at 780 nm emission is seen from both the core as well as the QWT. The QWT emits in a narrow intense peak $\sim $22 meV above the exciton emission from the core suggesting quantum confinement in a 10 nm quantum well. This QWT emission exhibits a $\sim $600 ps recombination lifetime, while the core decays in $\sim $1 ns. Preliminary PLE measurements exhibit possible excited state structure of this novel quantum-confined nanostructure.