Kinetics of GaAs metalorganic chemical vapor deposition studied by numerical analysis based on experimental reaction data

In order to develop a computer-assisted process optimization of In1-xGaxAsy P1-y metalorganic chemical vapor deposition (MOCVD), the kinetics of GaAs g rowth was studied as the first step. For the accumulation of reaction data of source materials, the decomposition rates of trimethylgallium (TMGa) and terriarybutylarsine (TBAs) were studied using a flow tube reactor and a Fo urier transform infrared spectrometer (FT-IR). Special attention was paid t o the effect of TBAs concentration on the decomposition rates of TMGa. The GaAs growth rate profile in a commercial MOCVD reactor was analyzed through both experiment and simulation. The profile was dependent on the gas veloc ity and total pressure. This dependency was explained by a reaction model w hich was deduced from the experimental observations: TMGa decomposes to a g as-phase intermediate which subsequently forms the GaAs film. The fluid dyn amic calculations combined with this reaction model led to growth rate dist ributions which agreed well with the experimental data. The analysis reveal ed that the GaAs growth rate is limited by the gas-phase reactions of TMGa as well as the mass-transport of the intermediates, and that precise measur ement of the reaction between TMGa and TBAs is essential for an accurate si mulation.