p-TYPE NITROGEN-DOPED ZnO MICRORODS PREPARATION BY SPRAY PYROLYSIS

Abstract

Nitrogen doped ZnO films with different N/Zn atomic ratio have been prepared by spray pyrolysis technique on glass substrate at 500°C. N/Zn atomic ratio has been selected 0, 0.5, 1, 2 and 3. The effect of N/Zn ratio on structural, optical and electrical properties has been investigated. Hall effect measurement studies show that the conductivity type of the films is affected by N/Zn ratio. The conductivity type of films changes from n for N/Zn = 0 and 0.5 to p for N/Zn = 1 and 2. Further increasing in N/Zn to 3 again led to n-type conductivity. p-type ZnO:N microrods film prepared with N/Zn = 1 has highest carrier concentration (1.36 × 1016 cm-3) and lowest resistivity (628 Ω.cm). All films are polycrystalline with hexagonal wurtzite structure. (002) plane is preferential orientation for all films. Surface morphology changes from rods to grains by increasing in N/Zn ratio. Optical transmission of the films increases with increasing in N/Zn ratio. Photoluminescence spectra at room temperature show the ultraviolet emission and two visible emissions at 440 nm and 520 nm. X-ray photoelectron spectroscopy analysis confirms the incorporation of nitrogen in ZnO:N film with N/Zn = 1 .