Electron paramagnetic resonance and photoluminescence spectroscopy were used to examine the structure and optical properties of Er-impurity complexes which were formed in float-zone samples by the multiple-energy implantation, at 77K, of Er; plus O or F. Samples which were co-implanted to give 3 x 1019/cm3 of O, and suitably heat-treated, exhibited a broad-line anisotropic spectrum. These samples yielded the most intense low-temperature photoluminescence spectrum, which contained several sharp peaks that were attributed to Er3+ in sites with predominantly cubic Td symmetry. Increasing the O concentration to 1020/cm3 produced sharp-line spectra; the strongest of which were attributed to two Er3+ centers with monoclinic C1h and trigonal symmetry. The principal g-values for the monoclinic center were g1 = 0.80, g2 = 5.45 and g3 = 12.60, with g|| = 0.69 and g- = 3.24 for the trigonal centers. The low-temperature photoluminescence spectrum from this sample showed additional sharp lines, but the total intensity was reduced when compared with the sample with 3 x 1019/cm3 of O. In samples which contained 1020/cm3 of O, at least 4 distinct centers were observed after certain heat-treatments; but not after others. Samples which contained 1020/cm3 of F, and were suitably annealed, produced an electron paramagnetic resonance spectrum which was attributed to Er3+ in a site with monoclinic C1h symmetry, where g1 = 1.36, g2 = 9.65 and g3 = 7.91.

Electron paramagnetic resonance and photoluminescence study of Er-impurity complexes in Si J.D.Carey, R.C.Barklie, J.F.Donegan, F.Priolo, G.Franzò, S.Coffa: Physical Review B, 1999, 59[4], 2773-82