Electronically active defects in cw beam-annealed Si. II. Deep-level transient spectroscopy

Deep-level transient spectroscopy, a powerful capacitance method for the study of deep defect levels in semiconductors, is used to study cw beam-annealing processes (scanned Ar+ laser and scanned electron beam) for ion-implanted Si. A dominant hole trap (Ev +0.45 eV), whose concentration increases by more than one order of magnitude with increasing laser power, was observed in cw laser-annealed samples immediately after sample preparation. 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; instead it decays as a function of time and transmutes to a shallow level at Ev +0.10 eV. The recovery of the Ev +0.45 eV level can be stimulated by low-temperature annealing or by minority carrier injection. For the furnance-annealed control samples, rapid quenching from sufficiently high temperature into water produces the same defect energy level and annealing characteristics as the laser-induced defects. By correlating these results with those in the published literature, the laser-induced, quenched-in defects are identified as interstitial Fe and Fe-B pair reactions in Si. Possible sources of Fe in Si will be discussed.