NH3-doped ZnO films were grown on <0 2 (2) over bar 4> oriented sapphire substrates at 610degreesC 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 NH3 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 NH3 flux showed p-type conductivity with hole concentrations of 10(16) cm(-3) and the other films with more NH3 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 NH3 combines with zinc by N-3 at 50 sccm flux of NH3, 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. (C) 2003 Elsevier Science B.V. All rights reserved.