Dynamics of T-site muonium states in gallium phosphide

We report on the motional dynamics of Mu- and the ionization processes related to the MuT acceptor state in n-type gallium phosphide. Muon spin resonance results on semi-insulating GaP suggest the presence of both Mu+ and Mu- diamagnetic states above ∼400K. From the growth step in the RF amplitudes, we obtain an energy of ∼0.82eV for the MuT acceptor-related hole ionization. The loss of the Mu- RF-component above 600 K yields an energy of ∼1.7eV, which is assigned to thermal promotion of an electron from Mu- to the conduction band. These two results locate the MuT acceptor level with respect to the valence and conduction band edges, respectively. Low-field spin precession and zero-field depolarization data on n-type GaP show a peak in diamagnetic fraction below 300 K, and a roughly linear increase in amplitude at higher temperatures.