Proximity gettering of platinum in proton irradiated silicon

Epitaxial silicon samples of n type have been implanted with 850 keV protons at doses of 5.8×1011 to 5×1013 H+ cm−2. Subsequent indiffusion of platinum at 700 °C for 30 min resulted in the presence of a single deep level, which is attributed to the platinum acceptor level, at 0.23 eV below the conduction band edge. Depth profiling of this level shows that the substitutional platinum is following the vacancy profile in the peak region around the projected range for the protons. In addition, at more shallow depths, a strong increase of the platinum concentration is also observed. Without ion implantation, no deep levels are detected after in-diffusion at 700 °C, while at 800 °C, the Pt deep level concentration is inferior to the one reached after preimplantation of hydrogen with a dose of at least 5×1012 H+ cm−2. In-diffusion at 600 °C into 5×1013 H+ cm−2 implanted samples did not lead to an enhanced platinum accumulation. A tentative explanation of this proximity gettering of Pt is proposed, which is for the first time observed after light-ion irradiation.