Extended x-ray-absorption fine-structure study of the local atomic structure in As+ heavily implanted silicon.

Abstract

Extended x-ray-absorption fine-structure (EXAFS) measurements were performed on As heavily implanted crystalline silicon, using total electron yield and fluorescence detection to study a large range of implanted doses: 5\ifmmode\times\else\texttimes\fi{}${10}^{15}$, 3, and 5\ifmmode\times\else\texttimes\fi{}${10}^{16}$ As/${\mathrm{cm}}^{2}$. The electrical deactivation of these samples after laser and subsequent thermal annealing (from 350 \ifmmode^\circ\else\textdegree\fi{}C up to 1000 \ifmmode^\circ\else\textdegree\fi{}C) is studied through the evolution of the first two shells of neighbors around As atoms. For an annealing temperature lower than 750 \ifmmode^\circ\else\textdegree\fi{}C, a model consistent with the EXAFS results is presented, in which the As deactivation is due to the formation of inactive clusters involving about 7 As atoms around one vacancy. For a higher annealing temperature (750--1000 \ifmmode^\circ\else\textdegree\fi{}C) the EXAFS results suggest the coexistence of clusters and precipitates in equilibrium.