Calculation of unimolecular rate constants for common metalorganic vapor phase epitaxy precursors via RRKM theory

Abstract

A mechanistic understanding of metalorganic vapor phase epitaxy (MOVPE) requires an understanding of fundamental parameters such as unimolecular gas phase (homogeneous) reaction rate constants. Using a large body of existing and estimated thermochemical data, Rice, Ramsperger, Kassel and Marcus (RRKM) theory was used to calculate the pressure dependence of the reaction rate constants for the MOVPE precursors Al(CH3)3 (TMAl), Ga(CH3)3 (TMGa), In(CH3)3 (TMIn), As(CH3)3 (TMAs), AsH3, and PH3. In addition, the pressure dependence of NH3 decomposition was calculated. The reaction paths for the group V hydrides involving the elimination of molecular as well as atomic hydrogen are discussed. The fall-off pressures, P 1 2, for TMGa and AsH3 in a hydrogen carrier gas at 900 K are approximately 2 Torr and 1 × 105 Torr, respectively. © 1990.