Luminescence of ZnSe nanowires grown by metalorganic vapor phase deposition under different pressures

Abstract

Quasi-one-dimensional ZnSe nanowires have been synthesized by metalorganic chemical vapor deposition on Si (001) substrates, sputter coated with gold catalyst, at various pressures using diethylzinc and diisopropylselendie. The nanowires appear to be randomly oriented on the substrate and some are slightly bent along their length. X-ray diffraction and scanning electron microscopy studies show that the nanowires are zincblende in structure and have a uniform cross section along its length, and an average diameter about 30 nm, regardless of growth pressure. Individual strands of the nanowires were examined by high-resolution transmission electron microscopy and were found to be single crystals elongated along the 〈112〉 crystallographic direction. Gold particles at the tips of the nanowires identified by transmission electron microscopy and atomic force microscopy indicate that the nanowires grow via the vapor–liquid–solid process. Room-temperature photoluminescence spectra of the ZnSe nanowires grown under different pressures show variations in their optical properties, despite their similarity in morphology and crystalline structure. At the optimal pressure of growth, strong near band-edge emission and very weak deep-level emissions are observed, indicating the low level of nonstoichiometric defects in the resulting ZnSe nanowires.