Modeling of a gallium nitride epitaxy growth system

An iodine vapor phase epitaxy (IVPE) system has been designed and built at North Carolina State University to grow high quality thick gallium nitride layer at the growth rate up to 80 μm/h with the deposition temperature of 1010°C and the pressure of 200 Torr. In order to optimize the growth process, a numerical model, which is capable of describing multi-component fluid flow, gas/surface chemistry, conjugate heat transfer, radiation heat transfer and multi-species transport, has been developed to help in design and optimization of the IVPE reactor. The gallium source weight reduce rate is converted into flow rate of gallium vapor and has been simulated as an inlet boundary condition of the tubular reactor. By matching predicted and experimental deposition rates, the heterogeneous reaction boundary condition is determined and applied to the substrate. Comprehensive two-dimensional computational simulations have been performed to study the temperature distribution, species mixing process and GaN deposition rate distribution on the substrate under different geometrical configurations and operating conditions; and the operating parameters have been optimized.