Nitrogen (4 x 10(15) ions/cm(2)) and indium (1 X 10(16) ions/cm(2)) ions with 200 and 170 keV, respectively, were co-implanted into a ZnO single crystal at room temperature. The ion-implanted sample was annealed at 800 degreesC under an oxygen atmosphere. The diffusion behaviors of N and ln in relation to annealing times were studied by SIMS. Diffusion of N in the crystal was not detected, while ln was observed to diffuse deeper into the single crystal during annealing. Due to diffusion of ln away from the surface, a second peak of ln was created which overlapped with that of N at the limited region of the ZnO crystal. It was confirmed by TEM observation that a band-like layer was formed in the post-annealed sample. (C) 2002 Elsevier Science B.V. All rights reserved.