A deep level at Ec-0.46eV (E1) was observed, using deep-level transient spectroscopy, in commercial epitaxial layers. This gradually decreased, at room temperature, and eventually vanished completely some 5300h after growth. New levels were observed at Ec-0.08eV, Ec-0.10eV, Ec-0.14eV and Ec-0.21eV. After annealing at 750C, the E1 level appeared again and all of the new levels disappeared. All of the levels, including E1, disappeared during annealing at temperatures above 1000C in O. It was suggested that the deep levels were due to contamination with Fe, because the energy levels and transition behaviors of the deep levels were very similar to published data on Fe in Si, and the deep levels could be caused to vanish by oxidation of the epitaxial layer.

Y.Takano, N.Fuma, N.Nakamura, K.Tashiro: Japanese Journal of Applied Physics, 1995, 34[2-10A], L1245-7