Evidence for diffusion-limited kinetics of ion-beam-induced epitaxial crystallization in silicon

The theoretical predictions of point defect related models for ion-beam-induced epitaxial crystallization (IBIEC) with reaction- or diffusion-limited kinetics are compared to each other and with experimental results. It is shown that the diffusion model provides the correct nuclear energy deposition and dose rate dependence of the IBIEC rate, whereas striking differences are observed for the reaction model. A compilation of several experimental data sets indicates a uniform diffusion regime for IBIEC in a wide range of defect generation rates. In this range the IBIEC rate can be estimated by a simple formula. The expected layer thickness dependence of the IBIEC rate is verified by in situ time-resolved reflectivity measurements. From these results it can be concluded that point defects originating from both the amorphous and the crystalline side contribute to IBIEC. It is speculated that divacancies are the defects which diffuse and stimulate the recrystallization at the amorphous/crystalline interface.