Film growth rate of InP and GaAs using TMIn, TMGa, TBAs and TBP in a horizontal reactor is numerically predicted and compared to the experimental results. Two different temperature boundary conditions are used for the film growth rate simulations. One is from two-dimensional heat transfer calculation at the mid-section of the reactor, whereas the other is from the full three-dimensional calculation. In the three-dimensional calculation, gas flow and heat transfer are analyzed for a full three-dimensional reactor including outer tube as well as the inner reactor parts to obtain exact thermal boundary conditions on the reactor walls. The film growth analyses results indicate that exact thermal boundary conditions are important to get precise film growth rate prediction since film deposition is mainly controlled by the temperature-dependent mass transport. The results also show that thermal diffusion plays an important role in the upstream region of the inner reactor. (c) 2005 Elsevier B.V. All rights reserved.