Effect of doping concentration and annealing temperature on nitrogen-doped ZnO thin films: an investigation through spectroscopic techniques

Undoped and nitrogen-doped ZnO (NZO) thin films were deposited by sol–gel spin-coating technique on glass substrates. The thin film preparation was accomplished using zinc acetate dihydrate, monoethanolamine and 2-methoxyethanol as the precursors. Ammonium acetate was used as the source of nitrogen for doping. The effect of dopants and the post-heating temperature on the various physical properties of the deposited films was explored. The X-ray diffraction studies reveal the polycrystalline nature of the films which possess a preferred c-axis orientation. Raman characterizations of the films show a clear indication of nitrogen incorporation in the films. The carrier concentration of the thin films was of the order of 10 ¹⁷ /cm ³ and resistivity as minimum as 0.371 Ω cm was observed for 1 at.% NZO thin films post-heated at 500 °C. The 1 at.% and 2 at.% doped NZO films post-heated at 300 °C and 1 at.%, 2 at.% and 3 at.% doped NZO films with post-heat treatment at 500 °C exhibited p-type conductivity. In the aging study, 500 °C annealed films retained p-type conductivity for 5 days.