LOW-PRESSURE MOVPE GROWTH OF ZNSE, ZNTE, AND ZNSE ZNTE STRAINED-LAYERSUPERLATTICES/

ZnSe and ZnTe single-crystal layers have been grown onto {100} GaAs su bstrates by low- pressure metalorganic vapor-phase epitaxy (LP-MOVPE) using the triethylamine-dimethylzinc adduct [DMZn(NEt3)] as the zinc p recursor. The selenium and tellurium precursors were H2Se (5% in H-2) and di-isopropyltellurium (DiPTe), respectively. These two semiconduct ors have been grown with different VI/II molar ratios, at different gr owth temperatures, and with an overall growth pressure ranging from 40 to 400 Torr. Optimal growth parameters have been determined by optica l means for the two materials. This information was then used to grow ZnTe/ZnSe strained-layer superlattices. We have studied structures gro wn on both ZnSe and ZnTe relaxed buffer layers which display a drastic dependence of the Stokes shift between photoluminescence and the opti cal bandgap on the nature of the buffer layer. Growth interruptions ha ve been used to optimize the optical properties of the superlattices. Theoretical modeling of superlattice band structures has been performe d using results of optical and structural characterizations. Observati ons of zone center transitions as well as excitons associated with the miniband dispersion of the superlattices are reported, in agreement w ith the theoretical calculation.