Photoluminescence evolution in GaAs/AlGaAs core/shell nanowires grown by MOCVD: Effects of core growth temperature and substrate orientation

Abstract

We explore the growth temperature dependence of GaAs/AlGaAs core/shell nanowires (NW) grown by metal–organic chemical-vapor deposition (MOCVD) on (100) and (111)B GaAs substrates. In-situ calibration of the growth temperature allows for a systematic variation with unprecedented resolution. Characterization by photoluminescence (PL) indicates that, at low growth temperatures, nanowires grown on (111)B substrates incorporate higher density of defects than wires on (100). On either substrate, nanowire core growth temperatures above 450°C result in rising defect luminescence in the PL spectra concomitant with the increased epitaxial growth on the nanowire sidewalls at these higher temperatures. This work presents a systematic study of nanowire growth conditions that reveals the correlation between the growth temperature of the GaAs core, the chosen substrate surface orientation, and the resulting optical properties of GaAs/AlGaAs nanowires.