The research is a renewal of a highly productive grant at Northwestern University (DMR-8701167). During the three years of support by the National Science Foundation two students were awarded the doctorate degree, one received the masters degree, and three students are in various stages of the doctorate degree. Seven papers were accepted for publication in refereed scientific journals, and seven more are in process. The research during that period emphasized the following: (1) transition and rare earth metals as electronically active defects in compound semiconductors, (2) flow modulation epitaxy of indium phosphide and its alloys, (3) defects in indium phosphide based heterostructures. The current research studies deep level defects in deliberately doped epitaxial indium phosphide and its alloys prepared by atmospheric pressure organometallic vapor phase epitaxy. A number of defect phenomena are being emphasized, for example, compensation mechanisms in heavily doped material, deep donor levels associated with substitutional impurities, deep levels in quantum wells and superlattices, and rare earth related impurities. The materials are being characterized using photoluminescence, photoconductivity, and deep level transient spectroscopy.
