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The demonstration of strong photoluminescence polarization anisotropy in semiconducting nanowires embodies both technological promise and scientific challenge. Here, we present progress on both fronts through the study of the photoluminescence polarization anisotropy of randomly oriented nanowire ensembles in materials without/with crystalline anisotropy, small/wide bandgap, and both III-V/II-VI chemistry (InP/ZnO nanowires, respectively). Comprehensive control of the polarization anisotropy is realized by dielectric matching with conformally deposited Ta2O5 (dielectric ratios of 9.6:4.41 and 4.0:4.41 for InP and ZnO, respectively). After dielectric matching, the polarization anisotropy of the nanowire ensembles is reduced by 86% for InP:Ta2O5 and 84% for ZnO:Ta2O5. [ABSTRACT FROM AUTHOR]

We explore the growth temperature dependence of GaAs/AlGaAs core/shell nanowires (NW) grown by metal–organic chemical-vapor deposition (MOCVD) on (1 0 0) and (1 1 1)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 (1 1 1)B substrates incorporate higher density of defects than wires on (1 0 0). 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. [ABSTRACT FROM AUTHOR]