A　systematic　computational　fluid　dynamic　(CFD)　study　was　performed　to　investigate　the　effects　of　operating　parameters　of　chamber　pressure　and　wafer　carrier　rotation　rate　on　the　GaAs/AlGaAs　deposition　rate　and　uniformity　in　vertical　rotating　disc　metal　organic　chemical　vapor　deposition　(MOCVD)　reactors.　It　is　shown　that　significant　improvement　of　the　reactors　efficiency　can　be　achieved　by　finding　the　optimal　chamber　pressure　and　wafer　carrier　rotation　rate.　By　degrading　chamber　pressure　and　varying　wafer　carrier　rotation,　it　is　finally　obtained　the　favorable　conditions　of　the　uniform　distributions　of　velocity　and　temperature　profiles　inside　the　reactor,　in　which　the　thermal　buoyancy　forces　are　effectively　controlled　and　the　flow　velocity　above　susceptor　is　further　increased.　©2010　IEEE.