IN-SITU FTIR ANALYSIS FOR THE THERMAL DECOMPOSITIONS OF TRIMETHYLGALLIUM AND TRIMETHYLGALLIUM AMMONIA ADDUCT

The thermal decompositions of trimethylgallium (TMG) and trimethylgallium-ammonia adduct (TMG:NH3) have been studied using Fourier transform infrared spectroscopy. A static cold-wall reactor is designed for use in the temperature range 25-1000-degrees-C, and the gaseous reactants and products are in situ analyzed to obtain the kinetic information. TMG:NH3 as well as TMG is decomposed around 500-degrees-C with liberation of the CH3 group. In the case of TMG:NH3, the CH3 group abstracts hydrogen from NH3, forming CH4. The decomposition of NH3 can be described as second-order kinetics, and that of TMG and TMG:NH3 as first-order kinetics. The decomposition rate constant of TMG:NH3 at 1.6 Torr is estimated to be log k1 = 15-63 (kcal/mol)/2.303RT.