Arizona State University (ASU), in collaboration with the University of Illinois at Chicago (UIC), will carry out experimentally intensive, multi- disciplinary research program on II-VI Compound Semiconductor-Based Light Emitting Devices. The program will emphasize the growth and doping by molecular beam epitaxy (MBE) and subsequent characterization of a novel type of lattice-matched heterostructure involving quaternary Zn1- xMnxSySe1-y confinement and cladding layers and ZnSzSe1-z active layers. the new quaternary alloy, which has not previously been grown, can be lattice matched to GaAs substrates over a wide range of band gaps extending from the blue well into the ultra-violet. Favorable band offsets are predicted for this system in both conduction and valence bands, based on interpolation of existing data on Zn1-xMnxSe/ZnSe and ZnSySe1-y/ZnSe heterostructures. True blue and violet lasers and heterostructure LED's based on defects that plague existing ZnSySe1-y/ZnSe/Zn1-xCdxSe II-VI laser structures. Ohmic contact layers based on Hg compounds will also be investigated to attempt to solve the currently critical problem of contacting p- type material.