Ion-beam induced effects at 15 K in MgO

Damage production in (100) MgO by 150 keV Ar and 450 keV Xe ion implantation is studied using Rutherford backscattering spectrometry in channelling configuration. Both implantation and analysis are performed at 15 K without change of the sample environment. With the suggested displacement energies of 55 eV for Mg and O for both ion species, a damage efficiency of 0.5 is determined. That means only 50% of the primary displacements survive the relaxation of the collision cascades of individual ions in crystalline MgO. When the collision cascades overlap, a complex defect structure is formed, most probably consisting of clusters of point defects or a distorted crystal and dislocation networks, which grow into depth far behind the projected range of the implanted ions. At high fluences, after this complex defect structure reached saturation, defects anneal during further implantation within the first 120 nm, which is attributed to the electronic energy loss of the implanted ions. (c) 2007 Elsevier B.V. All rights reserved.