Surface chemistry of dimethylaluminum hydride and trimethylaluminum on polycrystalline aluminum

Abstract

The surface chemistry of both dimethylaluminum hydride (DMAH) and trimethylaluminum (TMA) on a polycrystalline aluminum surface has been investigated with temperature-programmed desorption (TPD), secondary ion mass spectrometry (SIMS), and Auger electron spectroscopy (AES). Under our experimental conditions, DMAH adsorbs on the aluminum surface in its trimeric form and TMA adsorbs primarily in a dimeric form. DMAH desorbs from the atomically clean aluminum surface at 235 K, and TMA desorbs at 200 K. Both DMAH and TMA dissociate readily on the aluminum surface, and analysis by SIMS shows that this decomposition leaves a partially methylated aluminum surface at temperatures up to 500 K. DMAH desorbs from the carbon-contaminated aluminum surface at about 200 K. Both TMA and DMAH are found to produce methane product during the TPD experiments. The TPD experiments also suggest that the surface reactions of DMAH produce TMA as a reaction product. However, the reactions that form methane and TMA product occur in minor yield under our experimental conditions. By AES the surface is comprised of both aluminum and carbon after either DMAH-TPD or TMA-TPD. © 1991 American Chemical Society.