The goal of the research is to perform a systematic study of the deep level defects in compound semiconductors known as "DX Centers". The thrust of the research is to determine the atomic nature of the defects and to obtain information on the local electronic nature, so as to formulate a detailed microscopic model. X-ray absorption spectroscopy and Mossbauer effect spectroscopy are used to study gallium aluminum arsenide doped to various levels with tin and tellurium so as to produce shallow donor states, neutral "DX Centers" and ionized "DX Centers". High quality, single crystal gallium aluminum arsenide are being prepared by metallorganic chemical vapor deposition at the Laboratory for Solid State Physics and Solar Energy in Valbonne, France. The electrical behavior of the materials is characterized using Hall effect measurements. Photoemission, quantitative Auger electron spectroscopy and secondary ion mass spectroscopy are used to characterize the chemical composition and doping levels. The development of many promising devices using gallium aluminum arsenide compound semiconductors has been impeded substantially by difficulties in producing highly-conductive wide-band gap materials. Dopants that are commonly used cause deep level "DX Center" defects which are associated with deleterious properties such as persistent photoluminescence, reduced minority carrier lifetimes and recombination efficiencies.
