We have studied electrically active defects created by MeV heavy ion implantation in n-silicon. The buried damaged layer, created by implanting Ar~+ ions of energy 1.45 MeV and doses in the range 10~(13)-10~(14) cm~(-2) at room temperature, is embedded within the depletion layer of a Schottky diode. The defects are characterized using capacitance-voltage (C-V), current-voltage (I-V) and deep level transient spectroscopy (DLTS). Large concentration of electrically active defects are found to occur in a region several microns beyond the ion range or the damage profile predicted by Monte Carlo simulations. The dominance of a single trap in the damaged region is established from hysteresis effect in C-V, space charge limited conduction in forward I-V characteristics and DLTS results. With annealing in the temperature range of 400-600C, the observed changes in defect charge rpofile indicate that the effective electrical interface moves progressively towards the surface. C-V characteristics have been simulated using model charge profiles which suggest presence of a compensated region and a sharp negatively charged defect profile at a distance much larger than that expected from ion range. Our results constitute experimental evidence of migration and clustering of interstitial related defects, even at room temperature in case of high dose irradiation.
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