An investigation was made, of the electronic properties of Er in crystalline material, by using deep-level transient spectroscopic and capacitance-voltage measurements. The Er was incorporated by implantation into a p+-n junction structure. In order to determine the role which was played by O and defects, some samples were co-implanted with O and the annealing behavior of the deep-level spectra was studied at temperatures ranging from 800 to 1000C and times ranging from 5s to 0.5h. It was shown that O co-doping produced large changes in the Er-related deep-level spectra. In particular, there was a promotion from deep to shallow levels which enhanced the donor behavior of Er. When Er was implanted into pure crystalline Si, the spectrum was dominated by deep levels that arose from Er-defect complexes which were easily dissociated by heating. In O co-implanted samples, the formation of Er-O complexes with a characteristic level at Ec-0.15eV was observed. These complexes formed during annealing, and were stable at up to 900C.

S.Libertino, S.Coffa, G.Franzó, F.Priolo: Journal of Applied Physics, 1995, 78[6], 3867-73