Detailed information about the recrystallization and formation of defects in the ultra-shallow junction of implanted Si is a key for semiconductor fabrication below 20 nm regime. The surface quality of highly doped Si via annealing treatment would influence the fabrication and yield. Here, we employ nonlinear optics to study the correlated physical phenomena and underlying evolution of restructure of P+ ion implanted Si. Reflective second harmonic generation (RSHG) results reveal the restructure of the implanted Si layer that involves recrystallization, dopant activation and dopant diffusion in correlation with annealing temperature. In the implanted Si layer, defects cause inactivity in electrical properties and generate isotropic dipole contribution to the RSHG pattern. The trend of isotropic dipole contribution is consistent with the sheet resistance measurement that presents more information about the evolution of the restructure. At lower annealing temperatures, the precipitation and the interstitialcy pairs form due to the effect of transient enhanced diffusion, and then the isotropic contribution of the RSHG pattern and sheet resistance sharply increases because of aggregation of the dopants. The isotropic contribution of RSHG is an index of the transformation of the electrical property as well as estimate recrystallization during rapid thermal annealing. (C) 2015 Elsevier B.V. All rights reserved.