Deep level transient spectroscopy has been utilized to study the electronic defect levels in cw laser‐annealed and scanning electron‐beam‐annealed Si after ion implantation. For cw laser annealing, a dominant hole trap, whose concentration increases by more than one order of magnitude with increasing laser power, has been measured in slip‐free samples. In contrast, only a low concentration of hole traps appears in electron‐beam‐annealed Si. This laser‐induced defect is not stable at room temperature; it decays with time and can be restored by low‐temperature thermal annealing. For the furnace‐annealed control samples, rapid quenching from sufficiently high temperature into water produces the same defect energy level and annealing characteristic as the laser‐induced defect. These annealing characteristics of laser‐induced defects and thermally induced, quenched‐in defects are tentatively correlated with Fe and Fe‐B pair reactions in Si.