Axially-Resolved Luminescence Properties of Individual ZnSe Nanowires

We investigated axially resolved near-band-edge (NBE) and deep-level (DL) photoluminescence of individual ZnSe nanowires, using the techniques of two-photon excited luminescence imaging and time-correlated single photon counting, in a laser scanning confocal microscope. While the images of nanowires formed from the NBE luminescence appears to be uniform, a bright tip and a dim tail are observed in the images formed from the DL luminescence. At all locations of the nanowires, the luminescence decays are found to be dominated by a fast process at early time, followed by a slow component later. In addition, we report a flattened U shape distribution of the lifetimes along the length of nanowire for the NBE emission, and an elongated L shape distribution for the DL emission. Possible explanations for these results, involving carrier recombination dynamics and possibly plasmonic enhancements, are discussed.