Muon spin depolarization measurements performed on powdered InN with zero applied magnetic field reveal several positively charged diamagnetic muonium centers. At low temperatures, the ${\mathrm{Mu}}^{+}$ ground state is weakly relaxing with the characteristics of local tunneling motion, which changes to thermally activated diffusion above $350\mathrm{K}$. Additional signals imply stationary metastable ${\mathrm{Mu}}^{+}$ centers, which undergo successive activated transitions into the ground state at temperatures ranging from $250\text{to}400\mathrm{K}$. Above $450\mathrm{K}$, the ${\mathrm{Mu}}^{+}$ diffusion is interrupted by trap and release events. The high-temperature trapped state is different from any of the low-temperature sites. The energies associated with metastable-to-stable site changes, detrapping transitions, and thermal diffusion are extracted and possible sites for the observed ${\mathrm{Mu}}^{+}$ signals are discussed as a model for interstitial protons, ${\mathrm{H}}^{+}$.

• Received 24 May 2006

DOI:https://doi.org/10.1103/PhysRevB.74.245219