Ultrasonic influence on point defects in a dislocation free Si

Ultrasound (US) influence on dislocation free (DF) silicon is investigated. Ultrasonic waves attenuation (α), mobility of intentionally induced superficial dislocations, and minority carriers diffusion length (L) are measured from a dislocation free Cz-Si as a function of US amplitude. The general results consist of some changes in the properties under study that takes place in a threshold way. Under US deformation S>10^-5 attenuation a becomes nonlinear, dislocation mobility and so microplasticity vary significantly, and L increases up to 2 times. US in DF Cz-Si can effectively interact with a system of point defects. The acoustostimulated changes in DF Cz-Si properties under study are connected to ultrasonically activated transformations in a system of crystal point defects and their complexes. We find there are two thresholds of US deformation: S₁ ~10^-6 and S₂~10^-5. Under deformation S<S₁ the defect system rests unchanged, at S ₁<S<S₂ recombination properties and electrical activity of defects are modified, deformations S>S₂ the process redistribution takes place