Defect levels ofSnO2

A theory of the major chemical trends of impurity and vacancy levels in ${\mathrm{SnO}}_2$ is presented, based on a tight-binding Green's-function calculation. Our results account for the shallowness of levels associated with substitutional ${\mathrm{Sb}}_{\mathrm{Sn}}$ and ${\mathrm{F}}_{\mathrm{O}}$ centers and the unrelaxed oxygen vacancy. The behavior of defects in ${\mathrm{SnO}}_2$ and ${\mathrm{SiO}}_2$ is contrasted and discussed in terms of their bulk electronic structures and different coordinations.