Atomic model for theMcenter in InP

As described by Levinson et al., the metastable M center in electron-irradiated InP is a complex of at least two point defects that exists in two very distinct atomic configurations, one of which has two variants, and that transforms from one configuration to another with a ‘‘large lattice relax- ation’’ at low temperatures. When the Fermi level is not too close to either band edge, the complex is net neutral in one configuration and ionized triply positive in the other. We propose a simple atomic model for this center which identifies the neutral configuration as a second-nearest-neighbor antisite-vacancy pair (${\mathrm{V}}_{\mathrm{In}}$ ${\mathrm{}}^{\mathrm{-}}$-${\mathrm{P}}_{\mathrm{In}}$ ${\mathrm{}}^{+}$ ${)}^0$, and the triply ionized configuration as ${\mathrm{P}}_{\mathrm{In}}$ ${\mathrm{}}^{+}$ ${\mathrm{V}}_{\mathrm{P}}$ ${\mathrm{}}^{+}$ ${\mathrm{P}}_{\mathrm{In}}$ ${\mathrm{}}^{+}$. We identify the ‘‘large lattice relaxation’’ as nearest-neighbor hopping of an In vacancy, which was created by the irradiation.