Abstract
This work aims to study alterations in the crystalline structure of Cu doped ZnO nanowire clusters using micro-Raman spectroscopy and micro-photoluminescence (mu-PL) studies using the 325nm laser line of a He-Cd laser after transferring to a Si/SiO2 substrate. The samples were prepared via the sol-gel route and doped at 0.1, 0.3, 0.5 and 0.8% of Cu concentrations on glass substrates. The coating solution was prepared using zinc acetate as the dissolved precursor material, with a molarity of 0.2M. Furthermore 2-methoxyethanol was used as a solvent and copper acetate for doping purposes. The stabilizer was mono-ethanolamine (MEA) with the molarity ratio of the stabilizer and zinc acetate being 1. Miro-Raman spectroscopy revealed that Cu causes at the interstitial sites a distortion in the ZnO lattice, breaking down its translational symmetry which leads to increased intensity of the Al (LO) polar optical phonon modes near 570-580 cm(-1) as well as their broadening. Furthermore the mu-PL spectrum of the polycrystalline nanowires was characterized by a weak peak in the near-UV region due to the ZnO near-band-edge emission and a stronger broad peak in the visible as a result of the defect amount in the mid-gap region as well as green emission that is frequently associated to O-vacancies in ZnO.