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Top‐down fabricated nanoantenna architectures of both metallic and dielectric materials show powerful functionalities for Raman and fluorescence enhancement with relevance to single molecule sensing while inducing directionality of chromophore emission with implications for single photon sources. We synthesize the smallest bow‐tie nanoantenna by selective tip‐to‐tip fusion of two tetrahedral colloidal quantum dots (CQDs) forming a dimer. While the tetrahedral monomers emit non‐polarized light, the bow‐tie architecture manifests nanoantenna functionality of enhanced emission polarization along the bow‐tie axis, as predicted theoretically and revealed by single‐particle spectroscopy. Theory also predicts the formation of an electric‐field hotspot at the bow‐tie epicenter. This is utilized for selective light‐induced photocatalytic metal growth at that location, unlike growth on the free tips in dark conditions, thus demonstrating bow‐tie dimer functionality as a photochemical reaction center. [ABSTRACT FROM AUTHOR]

Abstract: Structural defects, found in gallium-phosphide nanowires, grown from Au catalyst on InP 〈111〉B substrate using metal organic molecular beam epitaxy, were extensively studied using Transmission Electron Microscopy (TEM). Several types of growth were analyzed: pure axial, axial–lateral and self catalyzed. Pure axially grown nanowires were found to be single crystals with wurzite crystal structure and Ga-polarity. These nanowires contained threading edge dislocation along the wire axis. The axial–lateral nanowires grew with zinc blend crystal structure and exhibited polycrystalline nature. Self catalyzed single crystalline nanowires possessed wurzite crystal structure with P-polarity and exhibited threading edge dislocations along their axis. [Copyright &y& Elsevier]