QUANTUM DIFFUSION OF MUONIUM IN GAAS WITH SHALLOW DONOR IMPURITIES

Muonium diffusion was studied in silicon doped GaAs by means of muon s pin relaxation in a longitudinal field. The muonium hopping frequencie s in two samples with n-type carrier concentration of 10(12-14) cm-3 a nd 8 x 10(16) cm-3 were deduced by using the model of fluctuating effe ctive local fields. We found that muonium diffusion is strongly influe nced by the dilute Si impurity in both samples in the temperature rang e below T(DELTA) congruent-to 30 K. The absence of such a behavior in compensated high-resistivity samples indicates that the presence of sh allow donor levels plays a decisive role for the tunneling diffusion o f muonium in semiconductors.