Anisotropic polarization of dislocation-related luminescence in thin ZnSe films

We have investigated the strong anisotropic polarization of the prominent Y line luminescence at 2.62 eV in thin ZnSe layers grown by molecular beam e pitaxy on (001)-oriented GaAs substrates. For thin ZnSe films a pronounced anisotropic polarization collinearly to the [ (1) over bar 10] crystallogra phic direction with intensity ratios up to 1:8 for polarizer orientations p arallel and perpendicular to [101] is found. In this samples the matrix lum inescence shows no preferential orientation of the electric field vector in the plane perpendicular to the axis of growth. For ZnSe films with a layer thickness just below the critical thickness we observed a fine structure o f up to nine subcomponents in the Y line spectrum. We interpret the Y line as a radiative recombination of an exciton bound to a 60 degrees alpha-disl ocation, which is dissociated into a 900 and 30 degrees Shockley partial di slocation bounding a stacking fault ribbon. We relate the fine structure to a discrete set of the stacking fault distances. (C) 1999 Elsevier Science B.V. All rights reserved.