Evidence for muonium emission from an SiO2 layer on n-type Si and the positive muon state in Si

Evidence for the emission of slow muonium atoms from a 3.0-nm-thick SiO2 layer covered on an n-type Si is reported. Also, upon applying an rf-resonance technique at the muon frequency, a time-differential observation of a delayed state-change from muonium to diamagnetic muon at room temperature was observed. Combining results obtained by use of longitudinal field decoupling and transverse spin rotation methods, the conversion rate was estimated to be 5 to 10 μs−1. Both of the above results, namely the observation of the emission and state-change of muonium, suggest a process in which μ+ initially captures an electron from Si, then quickly converts to μ+ again during thermal diffusion in the Si towards the SiO2 layer. Within the oxide layer, muonium is again formed and subsequently is emitted from the SiO2 surface.