Dhaka, VeerOksanen, JaniJiang, HuaHaggren, TuomasNykänen, AnttiSanatinia, RezaKakko, Joona PekkoHuhtio, TeppoMattila, MarcoRuokolainen, JanneAnand, SrinivasanKauppinen, EskoLipsanen, Harri2026-07-032026-07-031530-6984ORCID:/0000-0001-6033-7391/work/219179993https://hdl.handle.net/1885/733812810We report a new phenomenon related to Al-induced carrier confinement at the interface in core-shell GaAs/AlxGa1-xAs nanowires grown using metal-organic vapor phase epitaxy with Au as catalyst. All Al xGa1-xAs shells strongly passivated the GaAs nanowires, but surprisingly the peak photoluminescence (PL) position and the intensity from the core were found to be a strong function of Al composition in the shell at low temperatures. Large and systematic red shifts of up to ∼66 nm and broadening in the PL emission from the GaAs core were observed when the Al composition in the shell exceeded 3%. On the contrary, the phenomenon was observed to be considerably weaker at the room temperature. Cross-sectional transmission electron microscopy reveals Al segregation in the shell along six Al-rich radial bands displaying a 3-fold symmetry. Time-resolved PL measurements suggest the presence of indirect electron-hole transitions at the interface at higher Al composition. We discuss all possibilities including a simple shell-core-shell model using simulations where the density of interface traps increases with the Al content, thus creating a strong local electron confinement. The carrier confinement at the interface is most likely related to Al inhomogeneity and/or Al-induced traps. Our results suggest that a low Al composition in the shell is desirable in order to achieve ideal passivation in GaAs nanowires.8enAl segregationcore-shell nanowiresGaAs/AlGaAsMOCVDMOVPETRPL2013-08-1410.1021/nl401261384881584613