Excitons in semiconducting alloys

The physical behavior of excitons in binary semiconducting alloys in strong- and weak-binding limits is discussed. It is pointed out that for weakly bound Wannier excitons, an effective-medium model is more appropriate. The effect of single-particle lifetimes in alloys on the exciton lifetime is discussed. It is suggested that for excitons in $\mathrm{Cu}{\mathrm{Br}}_x{\mathrm{Cl}}_{1-x}$, such single-particle contributions to exciton lifetime are quite significant.