A study was made of the role of B ion energy in the engineering of dislocation loops for Si light-emitting diodes. Boron ions from 10 to 80keV were implanted into (100) Si at ambient temperature, to a constant fluence of 1015ions/cm2. After irradiation the samples were annealed for 1200s at 950C by rapid thermal annealing. The samples were analyzed by transmission electron microscopy and Rutherford back-scattering spectroscopy. It was found that the applied ion implantation/thermal processing introduced interstitial perfect and faulted dislocation loops into {111} habit planes, with Burgers vectors of a/2<110> and a/3<111>, respectively. The loops were located around the projected ion range, but extended in depth approximately to the end-of-range. Their size and distribution depended strongly upon the applied ion energy. In 10keV B-implanted samples, the loops were shallow, with a mean size of about 30nm for faulted loops and about 75nm for perfect loops. Higher energies yielded buried large and irregularly shaped perfect loops, up to ~500nm, coexisting with much smaller faulted loops. In the latter case, many more Si interstitials were bounded by the loops, which were attributed to a higher supersaturation of interstitials in as-implanted samples, due to separated Frenkel pairs. An interesting phenomenon was found in that the perfect loops achieved a steady-state maximum size when the ion energy reached 40keV. Further increases in the ion energy only increased the number of these large loops and made them bury deeper into the substrate. These results contributed to control of the size and distribution of dislocation loops during device fabrication.

Engineering of Boron-Induced Dislocation Loops for Efficient Room-Temperature Silicon Light-Emitting Diodes. M.Milosavljević, G.Shao, M.A.Lourenco, R.M.Gwilliam, K.P.Homewood: Journal of Applied Physics, 2005, 97[7], 073512 (7pp)