A new candidate for long lifetime short-wavelength light emitters made of hexagonal II-VT compounds has been proposed. Tn this payer, the results of theoretical design of ZnMgCdOSSe-based light emitters fabricated on (1 1 1) plane of GaAs and InP substrates is presented. The band lineups of CdZnS/ZnSSe and CdZnS/ZnMgS structures were estimated with Harrison's LCAO theory. Further, as for the first step of an experimental investigation on the growth of high phase-quality hexagonal II-Vt compounds, growth of CdZnS epilayers were examined on GaAs(1 1 1) substrate. The epilayers were characterized by high-resolution X-ray diffraction reciprocal space and pole figure measurements. In this study, the optimum growth temperature was 300 degrees C for hexagonal phase CdZnS, and the inclusion of cubic phase CdZnS drastically decreased with increasing Cd content at 300 degrees C.