Low temperature muonium behaviour in Cz-Si and Cz-Si_0.91Ge_0.09

Observation of muon and muonium behaviour in semiconducting materials provides valuable insight into analogous hydrogen states and dynamics. We have used muon spin rotation, relaxation and resonance techniques to observe the low-temperature muon behaviour in Czochralski-grown silicon and bulk, Czochralski-grown silicon-germanium alloy materials. Low temperature relaxation of the rapidly moving tetrahedral muonium species and its conversion to a diamagnetic species is seen in the Cz material but not in the float zone silicon, suggesting site change and subsequent ionisation are promoted by the oxygen impurity. This is also the first time muon behaviour in a Si_1-xGe_x alloy material has been presented.