Atomic displacement and ionization effects on the optical absorption and structural properties of ion-implanted Al2O3

Abstract

Ion‐induced lattice atom displacements in single‐crystal Al₂O₃ give rise to an optical absorption band at 204 nm as well as to expansion of the implanted volume. The 204‐nm absorption per unit energy into atomic processes is found to increase rapidly with decreasing incident ion mass. In contrast, light ions (H⁺, D⁺, He⁺) show less volume expansion per unit energy into atomic processes than do heavier ions. Furthermore, the volume expansion induced by heavy ion implantation can be completely relieved by H⁺‐ion implantation or by ionizing electron irradiation (8.16 keV). A simple model characterizes the results. The 204‐nm absorption is found to be proportional to the ion energy into electronic processes, and the expansion is proportional to the ion energy into atomic processes linearly reduced by the ion energy into electronic processes. The implications for defect production in CTR insulators are discussed.