Hydrogen implantation defects in MgO

摘要

Deuterium and hydrogen ions with an energy of 15 keV have been implatned in virgin MgO (100) single crystals and in single crystals containing helium implantation generated microcavities. Doses were varied from 2X10~15 to 2X10~16 cm~-2. The samples were annealed from room temperature to 950 K. The defects produced by hydrogen and the trapping of hydrogen at the defects were monitored by photon absorption and positron beam analysis. With this novel technique a depth distribution of defects can be determined for implantation depths from 0 to 2000 nm. The technique is very sensitive for vacancy and vacancy clusters, i.e. sites with low electron density. After 950 K annealing microcavities were observed for the 2X10~16 cm~-2 dose but not for the 10 times lower dose. During annealing up to 750 K point defects are mobile but the defect clusters remain small and filled with hydrogen. In samples which contain already microcavities, point defects and deuterium from the deuterium irradiation are accumulated by the microcavities. direct c 1999 Elsevier Science B.V. All rights reserved.