ZnSe/ZnSxSe1-x strained-layer supplattices with ZnS0.06Se0.94 buffers are grown on GaAs(100) substrates by molecular beam epitaxy and characterized by X-ray diffraction and low temperature photoluminescence. The main emission peaks in photoluminescence spectra can be attributed to the free exiton between the lowest electron subband and ground heavy-hole subband of ZnSe well. A blue shift of the excitonic peak is observed. The energy shift due to the strain and quantum confinement are theoretically calcu...