A STUDY OF 2-D AND 3-D TRANSPORT PHENOMENA IN HORIZONTAL CHEMICAL VAPOR-DEPOSITION REACTORS

2- and 3-D mathematical models for epitaxial growth in horizontal chemical vapor deposition reactors have been developed and modeling results have been compared with experimental results. The models include the partial differential equations describing the balance of mass, momentum, heat and species concentration, including multicomponent diffusion and thermodiffusion. The deposition process is assumed to be in the transport-limited regime. A detailed model for calculating the side wall temperature including thermal radiation, is included in the 3-D model. The equations are solved numerically, using a control volume based finite-difference method. The model is applied to MOCVD of GaAs from TMGa and AsH3. By varying the reactor height, inflow velocity and carrier gas, a large range of Rayleigh (Ra) and Reynolds numbers is covered. The calculations for the deposition rates in the midplane of the reactor are compared with experimental results from the literature. The 2-D model is found to give accurate results for large and medium width-to-height aspect ratio reactors operated at subcritical Ra only. For supercritical Ra conditions, 3-D calculations with detailed modeling of side wall temperatures give accurate predictions of experimental results. Modeling results are very sensitive to the use of correct thermal boundary conditions on the side walls. Deposition on the side walls is found to have little influence on the axial growth rate distribution. The relative importance of convection, diffusion and thermodiffusion for the species transport is studied. The exact Stefan-Maxwell equations for multicomponent diffusion are compared with an approximate approach, which was found to be very accurate. © 1990.