Epitaxial GaAs/AlGaAs core–multishell nanowires with enhanced photoluminescence lifetime

Abstract

The modulation of complex GaAs/AlGaAs core–shell nanowire heterostructures by the process of embedding GaAs quantum wells or AlGaAs quantum dots is feasible due to their minor lattice mismatch. In this study, we have grown GaAs/AlGaAs core–multishell nanowire heterostructures by molecular beam epitaxy and investigated their structural and optical characteristics. Our advanced electron microscopy investigations confirmed that we have grown wurtzite-structured GaAs/AlGaAs core–multishell nanowires, in which the AlGaAs inner-shell with a high Al concentration acts as a quantum barrier for the GaAs nanowire core and AlGaAs outer-shell. Photoluminescence measurements show that this unique nanowire heterostructure has a significantly increased carrier lifetime compared to the conventional GaAs/AlGaAs core–shell nanowire heterostructures. The observed prolonged carrier lifetime can be attributed to the increased electron confinement at the core–inner-shell interface and thus the delayed recombination of photoexcited electron–hole pairs. This study provides a possible design of nanowire heterostructures for high-efficiency optoelectronic devices.