We report measurements on the dynamics of negatively charged muonium ( ${\mathrm{Mu}}^{-}$) from 295 to 1000 K in heavily doped n-type GaAs:Si. The ${\mathrm{Mu}}^{-}$ center begins to diffuse above $500\mathrm{K}$ with a hop rate described by an Arrhenius function $\nu ={\nu }_0{e}^{{-E}_{\mu }/k_{B}T}$ where ${\nu }_0=5.6\mathrm{}\left(5\right)\times {10}^{12}{\mathrm{s}}^{-1\mathrm{}}$ and $E_{\mu }=0.73\mathrm{}\left(1\right)\mathrm{eV}$. Above $700\mathrm{K}$, relaxation from charge-state fluctuations is observed. The analysis of these data implies ${\mathrm{Mu}}^{-}\leftrightarrow {\mathrm{Mu}}^0$ conversions occur via alternating capture of holes and electrons, establishing Mu as a deep recombination center. Similar dynamics are expected for the isolated ${\mathrm{H}}^{-}$ center in n-type GaAs.

• Received 31 October 1995

DOI:https://doi.org/10.1103/PhysRevLett.76.3790