Abstract: Based on the growth requirement in MOCVD processes,the five optimum transport conditions are summarized as:uniform concentration boundary layer,uniform velocity boundary layer,uniform temperature boundary layer,reactants mixed uniformly before entering the reaction zone,and the exhaust gas expelled quickly without remixing with the reactants.Compared with the optimum conditions,the current MOCVD reactors of horizontal,vertical,planetary,showerhead,and RDR types are discussed.The main problems in horizontal reactors are reactant depletion,thermal convection,and reactor side effects.Using injection from showerheads and high speed susceptor rotation,the vertical reactors can obtain much more uniform boundary layers.The main problems in vertical reactors are the difficulty in expelling the exhaust gas without remixing with reactants and the difficulty in further enlarging the diameter of the rotating susceptor.

Key words: MOCVD, thin film growth, transport phenomena, reactor design, optimum condition