This research will focus on determining if impurity induced layer intermixing exists in semiconductor heterostructures comprised of quarternary materials. The interest in this phenomena lies in the ease with which optical waveguides and lasers can be patterned and the specific semiconductor materials are of importance for the lightwave technology area. The research will be a collaborative effort between the University of Illinois, the University of Paris in Orsay, and Thompson CSF. It will use French-supplied crystals and characterization equipment along with U.S.-supplied lithographs and processing steps.