Selective micro laser annealing for fluorescence tuning of carbon-incorporated zinc oxide nanowire arrays

Abstract

Carbon-incorporated zinc oxide (C-ZnO) nanowire (NW) arrays display controllable optical changes after being selectively annealed by a focused violet laser beam. A blue shift in the photoluminescence of the NWs from orange to green emission with enhanced optical intensity is observed. Systematic studies of C-ZnO NW modification with varying laser powers, scanning speeds and surrounding oxygen concentrations demonstrate a correlation between the oxygen concentration during laser annealing and the resultant extent of photoluminescence intensity change. Micro laser annealing and X-ray photoelectron spectroscopy as well as electron microscopy experiments point to a mechanism involving the segregation of carbon species to the NW surface followed by formation of zinc carbonate species on the NW surface. The work also provides further evidence of the miscibility of carbon in ZnO and the existence of carbon-based defects during ZnO NW growth.