STABILIZATION AND GROWTH INTERRUPTION EFFECTS AT ZNSXSE1-X ZNSE QUANTUM-WELL INTERFACES GROWN BY METALORGANIC VAPOR-PHASE EPITAXY/

ZnSxSe1-x/ZnSe quantum wells (QW) with and without growth interruption at the interface were grown using atmospheric pressure metalorganic v apor-phase epitaxy. It has been shown that growth interruptions have a major influence on the optical properties of the QW. An interruption of growth in ternary ZnSSe layers causes a quasi-QW photoluminescence (PL), explained by sulfur depletion of the layer. A stabilization is n ecessary to avoid a quasi-QW. High-quality ZnSSe/ZnSe QWs were achieve d by suitable stabilization with H2S and DESe during the growth interr uption at the interface, so a sulfur diffusion out of the barrier can be avoided. The QW thicknesses grown under these conditions were in ag reement with the nominal well thicknesses, and for stabilized 1-nm QWs we obtain a PL blueshift of 158 meV for x=0.68 and 60 meV for x=0.4 c ompared to the ZnSe band-edge emission. Characteristic QW-PL transitio ns at room temperature were observed for unstabilized QW grown with a long interruption time, t(p)=90 s. The thermal activation energies of the QW excitons investigated by temperature-dependent PL show that wit h decreasing interruption time an increased binding energy is obtained . The binding energy shows no dependence on the stabilization so that other effects (e.g., interface roughness and sulfur diffusion) may pla y a role. For QW with a low sulfur content (x=0.4) in the barrier mate rial, we find binding energies which fit to theoretical models. This w as not achieved for QWs with x=0.68.