Deformation effects on free excitons in CdSsub(1-x)Sesub(x) mixed crystals

Results are reported on the effect of uniaxial stress on the free exciton states in CdSsub(1-x)Sesub(x) crystals grown by the usual sublimation technique and having wurtzite-type structure in the whole composition range 0 <= x <= 1. It is shown that the parameters of the Bir-Pikus Hamiltonian for the mixed crystal system CdSsub(1-x)Sesub(x) vary linearly with the concentration x. As the changes of the elastic compliance constants between CdS and CdSe are very small (about 2 to 10%) this should be valid also for the interband deformation potential constants as to be expected in the framework of a virtual-crystal approximation. The effect of vanishing stress-induced mixing between A- and B-excitons states for CdSsub(1-x)Sesub(x) at about x = 0.5 makes desirable a more detailed theoretical analysis. (author)