THE ORIGIN OF THE FAST BLUE PHOTOLUMINESCENCE FROM SPARK PROCESSED SILICON

We show that the fast blue (maximum at about 3.0-3.2 eV) photoluminesc ence from spark processed silicon originates from tungsten doping when the sample is processed with a tungsten counter-electrode. A similar effect is found also for molybdenum and chromium. If a silicon tip is used as counter-electrode, the photoluminescence is about a factor of 30 weaker and red shifted with a maximum at about 2.2-2.3 eV, Because of the limited sensitivity of the RES technique used, transition metal impurities, such as Zn, are suspected but cannot be definitively prov en as the radiative centers in this case. (C) 1997 Elsevier Science S. A.