Defect physics investigations using positron and ion beams

The rate of defect accumulation due to ion irradiation is discussed. Silicon was implanted with 11.5 MeV Au-6 ions, to fluences ranging from 2 x 109 to 1 x 1011 cm-2. We find the measured defect concentrations C can be related to ion fluence φ via C = A φn, with A∼1600 and n∼1.0. The linear dependence of C on φ is consistent with expectations for the rate of accumulation of defects in the limit of low ion fluences, and is in contrast to previously reported values of n<1, which were obtained using higher fluences, for which significant overlap between individual damage cascades is expected. (orig.)