This award is made in the Office of Special Projects of the Chemistry Division in support of the continuing research of Dr. Andrew Barron at Rice University. The research will focus on the role of precursor molecular structure during chemical vapor deposition of Group 13-16 materials and the synthesis and reactivity of new Group 13-chalcogenide compounds. Having discovered that metastable solid phases can be formed from stable cage structure intermediates, conditions will be investigated which retain the cage structure in the gas phase. To this end, an aerosol-CVD system will be built which will eliminate gas phase decomposition. Specifically, cyclic and cage organometallic complexes of gallium and indium, sufides, selenides and tellurides will be synthesized and decomposed under conditions designed to preserve the structural integrity of the precursors, New phases will be characterized by Auger spectroscopy, XPS, TEM, SEM, x-ray diffraction and electron diffraction. Mechanistic studies of phase growth will be followed by time-of-flight mass spectrometry and matrix isolation of the decomposition products. Other studies will investigate the use of gallium-sulfide cages as molecular building blocks for extended mesophase structures and the use of caged gallium sulfide structures as models for alumoxanes in Ziegler polymerization. The fundamental chemistry of Group 13-16 chalcogenides is less well developed than the corresponding oxides This research will define the structural and kinetic requirements for the design and synthesis of new solid phases for applications in compound semiconductors, catalysis, and porous zeolite-like materials.
