A high‐conductivity layer has been observed within the amorphous region of heavily implanted (6×1016cm−2of 2.7‐MeV31P ions) (111) surfaces of single‐crystal Si after 500 °C annealing. The conducting layer was at the projected range of the31P+ions, and its location was determined from spreading resistance measurements. Microscopic examination, Coates‐Kikuchi lines (SEM), and ion channeling showed that the conducting layer was within an amorphous region. Very‐large‐amplitude low‐frequency ir interference reflection fringes developed with the onset of the conducting layer. We suggest that the large fringes are related to the dispersion produced by a damped plasma. Simplified model calculations are presented. The high‐frequency interference fringes related to the implantation‐induced structural damage virtually disappeared after annealing at 600 °C but the low‐frequency ’’plasma fringes’’ remain. SEM and microscopic examination showed that the amorphous region had epitaxially recrystallized.