A vacancy-related muon species in crystalline silicon

A new muonium centre, termed Mu(V), with weak hyperfine interaction has bee n discovered recently in crystalline silicon in longitudinal field quenchin g mu SR (LFQ) experiments (Schefzik et al., Solid State Commun. 107 (1998) 395). The signatures of this species were found in intrinsic, but not in do ped samples (dopant concentration larger than 10(16) cm(-3)). The centre is not formed promptly but results from a reaction in which normal muonium tr ansforms into the novel species. Since from LFQ experiments one can obtain only a rough estimate of the hyperfine tensor of Mu(V) it is now determined from zero-field (ZF) mu SR experiments. The hyperfine interaction is found to be axially symmetric around the [110] crystallographic axis with small hyperfine parameters. Properly rescaled it essentially agrees with the hype rfine tensor of the hydrogen centre VH, which has been discovered recently by Bech Nielsen et al. (Phys. Rev. Lett. 79 (1997) 1507) and which has been attributed to hydrogen trapped in vacancies. Accordingly Mu(V) is interpre ted as muonium trapped in a vacancy, in agreement with the interpretation g iven on the basis of the earlier LFQ data. (C) 2000 Elsevier Science B.V. A ll rights reserved.