H+ was implanted into single-crystal Si with a dose of 1016/cm2 and an energy of 30keV, and then He+ was implanted into the same sample with the same dose and an energy of 33keV. Both of the implantations were performed at room temperature. Subsequently, the samples were annealed (200 to 450C, 1h). Cross-sectional transmission electron microscopy, Rutherford backscattering spectrometry/channeling, elastic recoil detection, and high resolution X-ray diffraction were employed to characterize the strain, defects, and the distribution of H and He in the samples. The results showed that co-implantation of H and He decreases the total implantation dose, with which the surface could exfoliate during annealing. During annealing, the distribution of H did not change, but He moved deeper and its distribution became sharper. At the same time, the maximum of the strain in the samples decreased a lot and also moved deeper. Furthermore, the defects introduced by ion implantation and annealing were characterized by slow positron annihilation spectroscopy, and 2 positron trap peaks were found. After annealing, the maximum of these 2 peaks decreased at the same time and their positions moved towards the surface. No bubbles or voids but cracks and platelets were observed by cross-sectional

 
transmission electron microscopy. Finally, the relationship between the total implantation dose and the fraction of H in total implantation dose was calculated.

Evolution of Hydrogen and Helium Co-Implanted Single-Crystal Silicon during Annealing. X.Duo, W.Liu, M.Zhang, L.Wang, C.Lin, M.Okuyama, M.Noda, W.Y.Cheung, S.P.Wong, P.K.Chu, P.Hu, S.X.Wang, L.M.Wang: Journal of Applied Physics, 2001, 90[8], 3780-6