The Effect of Dose of H and He Sequential Implantation in Germanium

The effect of dose of hydrogen and helium sequential implantation in Germanium was investigated. The energy of H and He ions was 30keV, and 50keV, respectively. The dose of H was varied from 1E16, 3E16 to 5E16/cm², and the dose of He was kept at 1E16/cm². Atom force microscope was used to detect surface morphology and X-ray diffraction to show the strain evolution of the samples after annealing. We find it is hard for blistering for a fluence of 1E16/cm² as well as 5E16/cm². Further more, the strain relief is hampered in those two samples. We believe that the retarded attenuation of strain is due to the larger defect clusters especially those with high vacancy/hydrogen ratio formed during successive He implantation. As a result, for 1E16/cm², there is not adequate "free" H for the buildup of internal pressure of platelets, while for 5E16/cm², the implantation induced damage is quite severe and it may cause a partially amorphous zone.