INVESTIGATION OF [(PY)(ET)CO(DMG.GAET2)2] AND [NI(DMG.GAET2)2] (PY = PYRIDINE, DMG = DIMETHYLGLYOXIMATO) AS SINGLE-SOURCE PRECURSORS FOR DEPOSITION OF BETA-COGA AND NIGA BY MOCVD - CRYSTAL-STRUCTURE OF [(PY)(ET)CO(DMG.GAET2)(DMGH)]

The complexes [(py)(Et)Co(dmg . GaEt2)2], 1, and [Ni(dmg . GaEt2)2], 2, (dmg = dimethylglyoxime) were synthesized for study as potential precursors for Metalorganic Chemical Vapor Deposition (MOCVD) of beta-CoGa and NiGa. Complex 1 is easily hydrolyzed to [(py)(Et)Co(dmgH)(dmg . GaEt2)), 3; a single crystal X-ray structure was obtained for this product. Thermogravimetric analyses (TGA) under H-2 flow resulted in a residual mass of 35% at 650-degrees-C for 1 (residual for CoGa2 is 31%) and 29% at 500-degrees-C for 2 (residual for NiGa2 is 36%). The highest peaks in the electron impact MS corresponded to (MWt - py - 2C2H5)+, 1, and (MWt - C2H5)+, 2. The.next peaks for both compounds corresponded to loss of the remaining ethyl groups. MOCVD at 560-degrees-C resulted in polycrystalline beta-CoGa (using 1 as a precursor) and polycrystalline NiGa (2). Upon raising the temperature of the GaAs substrate to 630-degrees-C, 1 gave films with areas of epitaxial growth in a primarily polycrystalline beta-CoGa film; partial degradation of the substrate also occurs. EDS and XPS data showed how film composition can be controlled by precursor design. EDS analysis of the CoGa (1:2.4) and NiGa (1:2.0) films showed that stoichiometry of the precursors was principally retained. The films exhibit only negligible carbon or nitrogen contamination, but the oxygen content is relatively high (10-20%). XPS data show that oxygen near the surface is bonded to both Co and Ga, but in the film, oxygen is only bonded to Ga.