A modeling of reaction pathways in a TMAl/NH3/H-2 system including parasitic and polymeric reactions for computational simulations was constructed to study temperature and pressure dependences of growth rates and gas-phase chemistry in metalorganic vapor-phase epitaxial growth of AlN. AlN growth rates calculated were in good agreement with experimental data. Reactive molecules such as MMAlNH and Al-N became the major gas-phase species at the high-temperature range. With increasing pressure, the polymerization of these species was enhanced and AlN growth rate significantly decreased. (C) 2007 Elsevier B.V. All rights reserved.