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Gas phase and surface kinetic models describing the growth of InP by metallorganie chemical vapor deposition (MOCVD) using trimethylindium and phosphine diluted in hydrogen have been developed. A realistic model of the process was obtained by incorporating the kinetics into a two-dimensional transport model of the flow, heat, and mass transfer in horizontal MOCVD reactors. The unknown rate parameters of two surface growth reactions were estimated by comparing predicted growth rates of InP with the ones obtained from an atmospheric-pressure horizontal IVIOCVD reactor during heteroepitaxy of InP on GaAs. Sensitivity analysis of the reactions led to a reduced kinetic scheme, which can be used for predicting film growth rates with the same accuracy as a more detailed kinetic model, but with smaller computational requirements. The reduced kinetic model was subsequently tested against three sets of InP growth data reported in the literature and it successfully predicted observed growth rates and trends. Finally, parametric studies were performed on the computer to investigate the effects of changing the inlet velocity of the carrier gas, the operating pressure, and the inlet mole fraction of trimethylindium on the growth rate of the films. The proposed model may become a useful tool for reactor design, optimization, and scale-up of InP MOCVD.

A computational study has been performed to identify the onset of transverse buoyancy-driven recirculations during laminar flow of hydrogen and nitrogen in horizontal ducts with cool upper walls, and lower walls consisting of three sections: a cool upstream section, a heated middle section and a cool downstream section. The motivation for this work stems from the need to identify operating conditions maximizing the thickness uniformity, the interface abruptness and the precursor utilization during growth of thin films and multi-layer structures of semiconductors by metalorganic chemical vapour deposition (MOCVD). A mathematical model describing the flow and heat transfer along the vertical midplane of MOCVD reactors with the above geometry has been developed and computer simulations were performed for a variety of operating conditions using the Galerkin finite-element method. At atmospheric pressure and low inlet velocities, transverse recirculations form near the upstream and downstream edges of the heated section. These can be suppressed either by increasing the inlet velocity of the gas, so that forced convection dominates natural convection, or by decreasing the operating pressure to reduce the effects of buoyancy. The onset of transverse recirculations has been determined for Grashof (Gr) and Reynolds (Re) numbers covering the following ranges: 10−3 < Re < 100 and 1 < Gr < 106, with Gr and Re computed using fluid properties at the inlet conditions. The computations indicate that, for abrupt temperature changes along the lower wall (worst-case scenario), transverse recirculations are always absent if the following criteria are satisfied: \[(Gr/Re) < 100\quad {\rm for}\quad 10^{-3} < Re \leqslant 4\quad {\rm and}\quad (Gr/Re^2) < 25\quad {\rm for}\quad 4 \leqslant Re < 100.\]The predicted critical values of Re, which correspond to the onset of transverse recirculations, agree well with reported experimental observations. The above criteria can be used for optimal design and operation of horizontal MOCVD reactors and may also be useful for heat transfer studies in horizontal ducts with differentially heated lower walls.

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