Elevated temperature Ge implantation into Si and the effect of subsequent thermal annealing

The effect of implantation temperature and subsequent thermal annealing on the defect structure and strain state of Ge implanted Si is examined. It is shown that ion-beam synthesised SiGe Si strained layer heterostructures are most effectively fabricated by implanting at low temperatures, to form a thick amorphous layer, followed by solid-phase epitaxial crystallisation. In cases where extended defects are produced during implantation, high temperature (∼ 1050°C) annealing is shown to improve the quality of the material by substantially reducing the dislocation density. However, the annealed layers are shown to contain high dislocation densities, ∼ 2 × 10⁸ cm^-2, and significant Ge diffusion is observed. The dislocations are shown not to cause significant strain relief in the SiGe alloy layers but may be problematic in certain device applications.