Model of High-Temperature Diffusion of Interstitial Silicon Atoms in Silicon

Problem statement: Correct description of the anomalous phenomena determined by self-point defects in implanted silicon desires knowledge of their properties. Interstitial Si atoms themselves display anomalies in their behavior and firstly in existence of two very different values of the diffusion coefficient. Approach: We analyzed experimental results and proposed the model of diffusion of interstitial Si atoms in silicon in two shapes. Results: At low saturation Si atoms diffuse as isolated atoms with a low diffusion coefficient (~10-12 cm2 sec-1 at 900°C). At high supersaturation interstitial atoms diffused as Si-Si pairs, which had lower activation energy of migration and higher diffusion coefficients (~10-7 cm2 sec-1). Conclusion: The high diffusivity pairs were formed when two Si atoms hit in the same interstice. The atoms were not bound to one another by covalent bond. In a pair atoms were retained by a potential relief of the crystal.