Using first-principles total-energy methods, we calculate the formation energy for typical $\mathrm{Mn}$ defects in bulk $\mathrm{Si}$ and $\mathrm{Ge}$ and on (001) surfaces, from which the various $\mathrm{Mn}$ solubility limits are derived. Applying the theory for ultrahigh doping in semiconductors, we can understand why $\mathrm{Mn}$ solubility in epitaxially-grown $\mathrm{Si}$ and $\mathrm{Ge}$ films could be several atomic percent while the solid solubility limits are many orders of magnitude smaller. In particular, we suggest that hydrogen passivation of the surface during growth could be the key to such high solubilities.

• Received 1 March 2004

DOI:https://doi.org/10.1103/PhysRevB.70.033308