Surface morphology of MgO (100) crystals implanted with MeV Al+ and Al-2(+) ions

MgO(100) single crystals are implanted with 1.50-MeV Al+ and 3.00-MeV Al-2( +) ions at a fluence of 1 X 10(15) Al atoms cm(-2) under high-vacuum condit ions. The surface morphology of the substrate is measured in air using atom ic force microscopy and X-ray reflectometry followed by computer-simulated spectrum analysis. The ion-irradiated areas are found to protrude to differ ent heights on the nanometre scale. Small height differences are observed i n the areas irradiated by Al+ and Al-2(+) ions of comparable energy, dose r ate and total fluence. The results indicate that protrusions are most likel y caused by implantation-induced point defects (vacancies) generated in the crystal during implantation. Other possibilities for the cause of protrusi ons are discussed. Thermal treatment stimulates a partial recovery of the i mplantation damage and alters the topography of MgO surfaces.