SHIFT OF THE EXCITONIC RESONANCES BY THERMAL STRAIN AND LATTICE MISMATCH IN CDS THIN EPITAXIAL LAYERS

CdS was grown on BaF2 and SrF2 by hot wall epitaxy and on BaF2 by pulsed laser evaporation. Reflection measurements on the epitaxial layers showed energy shifts of A- and B-excitons. The shift on the surface of the film is different from that on the interface side. Calculations of the shift using known data of the deformation potentials confirmed the experimental results. We give here an explanation of these results taking into account thermal strain on the surface side and additional mismatch strain on the interface side.