Epitaxial growth of NH3-doped ZnO thin films on oriented sapphire substrates

Abstract NH 3 -doped ZnO films were grown on 〈 0 2 2 4〉 oriented sapphire substrates at 610°C by metalorganic chemical vapor deposition. The crystal quality of the films was investigated by X-ray diffraction method, and the results indicated that the crystal quality of the doped film with NH 3 flux 80 sccm (standard cubic centimeter per minute) is the best. At the same time, AFM images showed that this sample surface was also the most smooth. The Hall measurement results indicated that the film with 50 sccm NH 3 flux showed p-type conductivity with hole concentrations of 10 16  cm −3 , and the other films with more NH 3 flux still showed n-type, though their resistivity was very high. At last, the nature of nitrogen in the films was investigated by X-ray photoelectron spectroscopy (XPS). The results indicated that nitrogen in NH 3 combines with zinc by N −3 at 50 sccm flux of NH 3 , and the O:Zn:N ratio is 40:45.5:14.6. As the flux increases, some hydrogen binding to nitrogen has been introduced into the ZnO films, which causes the resistivity to decrease again.