The adsorption and thermal decomposition of trimethylamine alane on aluminum and silicon single crystal surfaces: kinetic and mechanistic studies

The mechanism and kinetics of the thermal decomposition of trimethylamine alane (TMAA) on aluminum and silicon single crystal surfaces in ultrahigh vacuum are reported. The products obtained are elementally pure aluminum thin films and gas phase hydrogen and trimethylamine. On single crystal aluminum substrates, epitaxial growth is observed. On Si(111), polycrystalline growth is noted although LEED studies suggest that the initial growth is heavily (111) textured. The reactive sticking probability on aluminum surfaces in the temperature range 80-280 K is low and we present evidence for the importance of TMAA decomposition at defects. At higher temperatures (t ≳ 320 K.) the reactive sticking probabilities are high and steady-state film growth is observed. Under these growth conditions, the rate of deposition is described by a single first-order rate law. The decomposition of TMAA on clean silicon and oxidized aluminum is kinetically complex and more highly activated than the steady-state growth process.