IRREGULAR SHIFTS OF EXCITONIC STATES IN REFLECTIVITY AND PL SPECTRA OF ZNSE CRYSTALS UNDER UNIAXIAL-STRESS

Splittings and shifts of excitonic states in ZnSe crystals under uniax ial stress along [100], [111] and [110] directions were studied by spa tially resolved spectroscopy of both the reflectivity and the photolum inescence (PL) at 5 K. These methods enabled us to check the local str ains in different surface microareas of deformed crystals and as a res ult to reveal the irregular free and bound exciton state shifts relate d to the influence of the strain non-uniformity and to the presence of structural imperfections (twins) in the crystals. It is shown that el astic deformation of twinned crystals along directions not exactly [11 1] gives rise to a doublet structure for all the bound exciton lines i n the pi spectra. New values of deformation potentials for ZnSe crysta ls were deduced. The anisotropic influence of the uniaxial stress on t he free and bound exciton state splittings was determined.