Muonium acceptor states in high GeSi_{1 - x} Ge_x alloys

Muon spin rotation and resonance studies of Czochralski-grown silicon germanium alloys with high Ge content have determined muonium (Mu) donor and acceptor energy levels. High-TF and RF μSR measurements on 90% and 84% Ge content SiGe alloys show Mu acceptor energy levels of 13.5 ± 5.2 and 77 ± 12 meV, respectively, as well as a split tetrahedral Mu hyperfine signal. In addition to observing two Mu_T states in these samples, we see in Si_0.16 Ge_0.84 a possible shallow acceptor signal in our transverse field data as a time-delayed process most likely arising from neutral Mu states. Our fits obtain a relaxing diamagnetic signal that shows bond-centered Mu ionization above 150 K and a shallow signal below roughly 50 K, split ± 80 kHz from diamagnetic Mu.