{111} defects in 1-MeV-silicon-ion-implanted silicon

Abstract

Rodlike defects with the {111} habit plane have been identified by electron microscopy, at a well-defined depth below the surface of silicon specimens subjected to a 1 MeV Si ion implantation (1\ifmmode\times\else\texttimes\fi{}${10}^{14}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ dose, followed by 900 \ifmmode^\circ\else\textdegree\fi{}C annealing for 10 sec), and coexistent with defects on {311} habit planes. Energy minimization calculations using the Stillinger-Weber potential were carried out on a self-interstitial atomic configuration; the final relaxed atomic configuration consists of five- and eight-membered rings. Calculated images based on this atomic model match ``double-spacing'' experimental high-resolution electron microscopy images. The energy minimization calculation suggests a displacement vector of a〈111〉/10, perpendicular to the habit plane, for the {111} defect. Diffraction contrast experiments revealed that, in the present specimens, about a tenth of the rodlike defects have this displacement vector. The {111} defects were also observed using a 120-keV electron microscope, below the critical energy of 170 keV for generating Frenkel pairs in Si by electron irradiation. This indicates that the {111} defects can be generated by ion implantation and annealing.