Tin-vacancy complexes in e-irradiated n-type silicon

Electron irradiated n-type float-zone silicon containing tin has been investigated by EPR, In addition to the well known Si-G29 signal due to the SnV(0) complex we have observed a group of similar EPR signals with strongly anisotropic, near-trigonal g tensors, which we label DK4. The corresponding defects have S = 1/2 and contain one tin atom. Exposure to light at low temperatures reduces the G29 signal and increased the DK4 signals, whereas subsequent annealing at 200 K restored the initial signal strengths. A linear relationship between the light-induced decay of G29 and the growth of DK4 was established, indicating that DK4 arises from SnV(0) by a change of the charge state. From the observation of DK4 in the n-type material after cooling in the dark we assign DK4 to SnV(-). The acceptor level E(-/0) (SnV) implied by this assignment has not been determined, but the observations indicate a position below the single-acceptor level of the divacancy (E(c) - 0.42 eV). (C) 1999 Elsevier Science B.V. All rights reserved.