The gas mixing system is a clean, leak-free, stainless steel system designed to uniformly mix metallorganic and hydride sources prior to reaching the growth zone. The function of the gas mixing manifold is crucial for growing superlattices, quantum well structures and for reducing the memory effect associated with some dopant sources. The gas mixing manifold first stabilizes the flow and then directs the flow to the reaction chamber. At other times the flow is sent directly to the vent. The gas handling manifold has air-pressure-controlled valves that can be opened or closed.