Surface amorphization in AlO induced by swift heavy ion irradiation

Okubo, Nariaki   ; Ishikawa, Norito   ; Sataka, Masao; Jitsukawa, Shiro

Microstructure in single crystal AlO specimens developed during irradiation by 70-160 MeV-Xe ions has been examined with transmission electron microscope (TEM). Amorphization was observed around 800 nm depth through from ion-beam incident surface of the specimen. The amorphization was also evaluated with XRD technique. TEM observation also indicated that tracks were formed by irradiation at the deeper region than that of the amorphous layers. The number density and size of the tracks have been decreased with the depth from the ion-incident surface. It suggests that amorphization has been occurred by the overlapping of the tracks. It was also obvious that the thickness of the amorphous layers were smaller than those observed in poly-crystal alumina specimens. This may be interpreted by the difference of electronic energy loss in the specimen; lower energy loss for single crystal specimens for their crystallographic orientation against to the incident ion-beam.