9417763 Haller The special properties of single crystals (bulk and Layered structures) with isotopically controlled composition will be used in self and dopant diffusion studies. Internal isotope interfaces in superlattices of 70Ge 74Ge with approximately 200 nanometer thick individual layers will be investigated by Secondary Ion Mass Spectroscopy. Materials with more complicated diffusion processes will be studied in the second phase. Group II-VI direct bandgap zinc based compounds and gallium nitride, blue light emitters, will be doped with mono-isotope dopants. They will be investigated using local vibrational mode spectroscopy. The simplification in impurity spectra caused by isotope control promises a new level of understanding of the local impurity structure. The results may lead to improved modeling of devices with ever decreasing dimensions and increasing complexity. %%% The end of the cold war has opened up the possibility of obtaining large quantities of isotopically highly enriched semiconductor materials from Russia and the Ukraine. These isotopically pure materials will be used to study atomic diffusion in a completely new way. Multilayers of different isotopes of the same elements (e.g. germanium 70 and 74) will be formed by thin film crystal growth. Interdiffusion at the interface will be investigated using Secondary Ion Mass Spectroscopy. After studying chemically pure isotope structures, doped systems and mutlilayers of some new semiconductors used in optoelectronics applications will be studied. The vibrational; spectra of a range of low mass impurities in isotopically pure semiconductors will also be investigated. The results will lead to improved modeling of electronic devices with every decreasing dimensions and increasing complexity. ***
