Photocurrent spectroscopy of single GaAs/AlGaAs core-multishell nanowire devices

We investigate the optical and transport properties of single GaAs/AlGaAs core-multishell Quantum Well Tube (QWT) nanowire heterostructure. The QWT is defined by a thin (8 nm) GaAs layer embedded inside a thick Al_0.4Ga_0.6As shell which surrounds a 50 nm diameter GaAs NW core see Fig.1. The electrons and holes in the thin GaAs shell are radially confined and are free along the nanowire length. The radial confinement results in confined quantum states as shown in the schematics in Fig.1. These nanowires growth was achieved by two temperature MOCVD growth techniques [1, 2]. Optical studies of these nanowires show high quantum efficiency of the QWT ground state photoluminescence compared to the core luminescence. The shift to higher energies above the core corresponds to increasing quantum confinement of the ground state transition of the quantum well tube [1]. The energy eigenvalues depicted in Fig.1 are numerically calculated values of the energies of the electrons and holes confined to the quantum well tube where the hexagonal symmetry of the nanowires is approximated by cylindrical symmetry.