Recent advances in high dose ion implantation The surface properties such as depth profile, techniques have produced silicon-on-insulator chemical bond and structure, and electrical prop-(SOI) substrates for the fabrication of electronic erties of oxide and nitride layers in aluminium devices. Oxygen or nitrogen has been widely used produced by high dose implantation of oxygen and to supply the buried insulating layers in silicon because silicon oxide and silicon nitride are insunitrogen ions were investigated. High doses of lators that have widespread applications in the oxygen (4 ร1018 ions cm -2) and nitrogen (2xlO 1~ ions cm-:) molecule ions were implanted into semiconductor industry [6-8]. In contrast, it has been demonstrated that polycrystalline and single-crystal aluminium sheets oxygen or nitrogen implantation into metals can using low current densities of 150 keV at room lead to the formation of metal oxide or metal temperature. The implanted layers were characternitride at room temperature [9, 10]. For example, ized by means of Auger electron spectroscopy, X-ray photoelectron spectroscopy, X-ray and aluminium oxide (A1203) or aluminium nitride transmission electron diffraction, transmission (A1N) can be synthesized by high dose implantaelectron microscopy and IR spectroscopy. The tion of oxygen or nitrogen ions into aluminium. Since AI203 and A1N are insulating materials electrical resistivity and breakdown electric field with thermal and chemical stability, they have strength of oxide and nitride layers were measured wide applications in film coatings and electronic by current-voltage characteristics. devices. So far, many groups have reported the It was found that high dose oxygen ion implanformation of A120 3 [11-17] and A1N [ 18-27] tation produces microcrystalline v-AL03, whereas layers by ion implantation, and also their surface implanted nitrogen leads to polycrystalline or structure or electrical properties have been invessingle-crystal AlN layers at room temperature tigated. Most of the earlier studies, however, were without any thermal annealing. It is possible to undertaken to use the evaporated aluminium form electrically insulating layers in aluminium using this technique, films as target substrates. Only a few results using bulk aluminium have been reported by Musket et al. [15] and Kido et al. [22]. Musket et al. reported 1. Introduction the formation of subsurface A1203 layers in bulk High dose ion implantation has been applied to aluminium. They implanted (1-16) ร 1017 atoms various materials not only to improve the surface cm-2 using low current densities of 180 keV 02 + properties, but also to form compound layers or near room temperature [15]. However, they new metastable alloys in the near surface [1-5]. observed oxygen bubbles for the high dose oxygen implants [16] and electrical properties *Paper presented at the Sixth International Conference on were not shown. Kido et al. investigated the A1N Surface Modification of Metals by Ion Beams, Riva del layers formed by 700-800 keV N2 + implantation