Surface segregation of implanted ions: Bi, Eu, and Ti at the MgO 100/surface

Surface segregation of Bi, Eu, and Ti implanted at the MgO 100.surface has been investigated by using time-of-flight coaxial impact-collision ion scattering spectroscopy CAICISS.and reflection high energy electron diffraction RHEED.. It is observed that implanted-Bi is concentrated at subsurface layers of MgO. On the other hand, it is found that Eu segregates to the outermost surface layer by annealing at 10008C, in addition to the simultaneous segregation of Ca which is included in the bulk as impurity of 40 ppm. During the implantation of Ti at the MgO substrate, it is found that C makes inroads upon the substrate. Surface segregation of Ti itself is not observed by annealing the substrate from 4008C to 10008C. It is concluded that nature of surface segregation of these systems primarily depends on the size of the implanted ions. q1998 Elsevier Science B.V. All rights reserved