Muonium defect levels in Czochralski-grown silicon-germanium alloys

We report Muonium (Mu) donor and acceptor levels in Czochralski-grown Silicon Germanium alloys (Cz-Si_1-x Ge_x). Measurement of these defect energies provides an analogous examination of Hydrogen defects that are otherwise inaccessible. Temperature-dependent Muonium fractions in several alloy samples (x=0.20,0.45,0.77,0.81,0.84,0.90,0.91,0.94,0.98) show charge-state transitions assigned to Mu donor and acceptor ionizations. Our results indicate a deep Mu donor level across the alloy system. The Mu acceptor level is deep in pure Si and valence-band resonant in pure Ge; we specifically examine the compositional dependence of the Mu T0 acceptor ionization energy in Ge-rich alloys, where this level crosses into the valence band.