Visualization of vacancy type defects in the R_P/2 region of ion implanted and annealed silicon

Recently, a strong metal gettering in Si after ion implantation and annealing has been detected at depths between the surface and the projected ion range R_P, indicating the presence of residual defects therein. The theoretical ballistic calculations ascribed the R_P/2 effect to the excess vacancies resulting from the forward momentum transfer of the implanted ions into the silicon matrix. So far, the gettering centers for metals at R_P/2 have been considered to be too small to be visible by Transmission Electron Microscopy (TEM). We show that the crucial point for visualization of the vacancy type defects at R_P/2 by TEM is the specimen preparation technique. The very widely used conventional ion milling technique for TEM specimen preparation introduces damage on the surface of the XTEM specimen, which blurs the original defect structure at R_P/2 and obscure it of being visualized. Only the TEM specimens prepared by cleaving reveals cavities at R_P/2. Minimum damage production caused during the preparation of the TEM specimen using cleaving allows the imaging of the cavities at R_P/2.