Off-Axis Electron Holography of Nearly-Spherical Faceted Voids in Self-Annealed Implanted Silicon

Nearly spherical voids, with a size on the order of some tens of nanometers, are defects that have recently attracted a renewed interest, due to their capability to getter impurities and point defects in silicon. High-resolution electron holography is employed here to study the three-dimensional configuration of nearly spherical cavities obtained by 100keV P+ ion bombardment of a silicon wafer using an ion beam with a power density of about 40 W/cm2 for 4 sec. Reconstructed phase maps have been used to obtain the qualitative topography of the cavity shape as well as quantitative measurements of the depth variations. Faceting of the nearly spherical voids is discussed in detail.