[en] Ion implantation when used as a doping technique introduces damage to the surface of a silicon wafer. This damage in turn may result in formation of dislocation loops or stacking faults, depending upon the subsequent heat treatment. These defects in turn may degrade electrical properties in a P-N junction. The importance of the location of defects on the P-N junction performance has not been studied in detail. In this work, P-N junctions were fabricated, tested electrically, and analyzed with transmission electron microscopy (TEM). Two types of defects, dislocation loops and stacking faults, were introduced into P-N junction. Sometimes dog-bone shape stacking faults were produced. TEM analysis revealed that the dog-bone fault is a stacking fault decorated by precipitates. High magnification (200K) revealed two kinds of precipitates, individual plates and colony clusters. Colonies exhibited Moire fringes that were used to characterize their crystallographic structures. X-ray Energy Dispersive Spectroscopic data from these two precipitates showed that colonies consisted of Ni, Cu and Si, while the plate contained Ni and Si only. It was concluded that the plate type is pure NiSi₂ and that the colonies are metastable (Ni/sub x/, Cu/sub 1-x/)Si₂ due to Cu alloying