Direct imaging of the spatial diffusion of excitons in single semiconductor nanowires

We use spatially and temporally resolved photoluminescence to measure exciton diffusion in single zinc blende GaAs/AlGaAs core/shell and mixed phase InP nanowires. Excitons in the single phase GaAs/AlGaAs nanowires are seen to diffuse rapidly throughout the nanowire with a measured diffusion constant ranging from 45 to 100 cm2/s, while in the mixed phase, InP nanowire electrons and holes are seen to rapidly localize to the quantum confined states in the zinc blende and wurtzite segments, respectively. The diffusion constant in the GaAs/AlGaAs nanowire is similar to the best hole mobilities observed in modulation doped heterostructures.