Lattice matching effect on the luminescent properties of n-ZnSSe on GaAs grown by MOCVD

Abstract

Lattice matching effects on Br-doped ZnSSe/GaAs system were studied. A homogeneous image was observed in the lattice matched system ZnS0.09Se0.91/GaAs by SEM cathodeluminescence (CL), whereas there were many dark spots on CL images for the lattice mismatched ZnSe/GaAs system. The dislocation density on the (100) surface was estimated as 108 cm-2 from TEM cross sectional images and 107 cm-2 by etch-pit measurement in the lattice mismatch system. The dislocation density decreased to below 106 cm-2 from TEM estimation and 104 cm-2 from EPD measurement by lattice matching. The photoluminescence (PL) intensity at room temperature for lattice matched ZnSSe was about 10 times larger than that for lattice mismatched ZnSe with the same doping concentration (n=1016 cm-3). These studies proved that precise lattice matching is needed to obtain crystals which have a high luminescence efficiency. © 1990.