Localization of excitons on planar defects in semiconductor crystals

Localized states of a large-radius exciton on a planar short-range defect, which is simulated by the potential $-V\delta(z)$, are studied theoretically. The ratio of the amplitude $V$ to $e^2/\varepsilon$ ($\varepsilon$ is the dielectric constant) determines two asymptotic regimes of weak and strong localization. In both cases, the radiation lifetime of the exciton increases with $V$ according to power laws $V^{1/4}$ and $V$ in the cases of weak and strong localization, respectively.