| This thesis describes muSR measurements aimed at characterizing diamagnetic (i.e. charged) muonium (Mu = mu+e -) centers in GaAs and Si. Using muon level crossing resonance (muLCR), the structure of the positively charged center (i.e. Mu+) in p-type GaAs at 50 K is determined. Mu+ is found to sit near the center of a stretched Ga-As bond, with nearest neighbor separations of rGa = 1.83 +/- 0.10 A and rAs = 1.76 +/- 0.10 A. In addition, transverse field (TF) and muLCR measurements are performed in semi-insulating GaAs at 10 K in the presence of an electric field that is used to enhance the diamagnetic signal. The TF relaxation is found to be consistent with that of Mu + for electric fields between ≈ 1--15 kV/cm. Level crossing data at 20 kV/cm show a resonance signature identical to that of Mu+ in p-type GaAs. As well, a new technique (dubbed ZeroX) is presented to study low-spin semiconductor systems. Measurements in p-type GaAs are conducted as proof-of-principle, and new data from p-type Si are presented. |
