ELEVATED-TEMPERATURE GE IMPLANTATION INTO SI AND THE EFFECT OF SUBSEQUENT THERMAL ANNEALING

The effect of implantation temperature and subsequent thermal annealin g on the defect structure and strain state of Ge implanted Si is exami ned. It is shown that ion-beam synthesised SiGe/Si strained layer hete rostructures are most effectively fabricated by implanting at low temp eratures, to form a thick amorphous layer, followed by solid-phase epi taxial crystallisation. In cases where extended defects are produced d uring implantation, high temperature (similar to 1050 degrees C) annea ling is shown to improve the quality of the material by substantially reducing the dislocation density. However, the annealed layers are sho wn to contain high dislocation densities, similar to 2 x 10(8) cm(-2) and significant Ge diffusion is observed. The dislocations are shown n ot to cause significant strain relief in the SiGe alloy layers but may be problematic in certain device applications.