Effect of the surface on ion-beam damage build-up in ZnO

Lattice disorder in ZnO irradiated with heavy ions is anomalous, exhibiting an intermediate peak (IP) between the surface and bulk. Bombarding (0 0 0 1) ZnO single crystals with 500 keV Xe ions at two angles shows that the formation and propagation of the IP are independent of the displacement generation profile. The ZnO surface plays the dominant role in IP formation and propagation. The IP likely traps and annihilates mobile point defects, as evidenced by a step in Rutherford backscattering/channeling spectra.