Sub-bandgap luminescence centers in silicon created by self-ion implantation and thermal annealing

Abstract

We investigated the conditions for the generation of silicon sub-bandgap luminescence centers (W, R, and D1 centers) in p-type silicon wafer by self-ion implantation and thermal annealing. Luminescence centers and their spatial distributions were probed by measuring their photoluminescence (PL) spectra before and after sequential removal of top surface layers. It was demonstrated that the optimal annealing temperature for W-line is ∼300 °C. The strongest R-line is observed in the sample with a dose of 1014 cm−2 and at an annealing temperature of 700 °C. The creation of D1-band requires a minimum dose of 3×1014 cm−2 and a minimum annealing temperature of 800 °C. PL versus etch depth measurements indicate that within the studied dose range, the W-line luminescence centers are distributed beyond twice the ion projected range (Rp≈400 nm), R-line centers are located slightly deeper than the Rp, and D1 related defects are distributed at about the same depth as Rp. These results provide valuable information for fabricating the silicon-based infrared light sources.