Spatial correlation between primary and secondary defect profiles after high dose self-irradiation of Si crystals

Abstract

Primary and secondary defect profiles in silicon crystals have been investigated after 2 MeV and 80 keV Si⁺ irradiation by electronmicroscopy and optical reflectivity measurements. The primary irradiation damage leads to a more or less amorphous layer in the sample depending on target temperature and dose. The distance from the surface and the thickness of the amorphous layer determine the residual damage structure after annealing. In general two defect layers exist: one consisting of interstitial loops and misfit dislocations is formed approximately in the center of the region which was amorphous and where the two recrystallization fronts meet each other during annealing in the temperature range from 450 to 600°C. The other layer consisting of extrinsic stacking faults due to precipitation of implanted excess interstitials develops below the amorphous region. The appearance of this general defect profile after different implantation and annealing treatments is discussed.