Effects of 80 keV N-ion implantation on structures of ZnO films

ZnO thin films were implanted at the room temperature by 80 keV N-ions to 5.0 x 1014, 5.0 x 1015 or 5.0 x 1016 ions/cm2, the structural characteristics of the samples were investigated using X-ray diffraction (XRD) spectrometer and transmission electron microscopy (TEM). It was found that the un-implanted ZnO films are constituted of columnar crystals which are very compact and of preferred c-axis orientation. After N-ion implantation, the crystal lattice constant and the biaxial compressive stress increased with the increasing of the N-implantation dose. In the 5.0 x 1016 N-ions/cm2 implanted ZnO sample, a new XRD peak due to defects or N-dopants appeared. Moreover, defects and localized disordering in the 5.0 x 1015 N-ions/cm2 implanted ZnO films have been observed under high resolution TEM measurement. However, N-ion implantation could not change significantly the crystal structure of the ZnO films. Possible mechanism of the structural modification of ZnO films by N-ion implantation was briefly discussed. (authors)