THE RELATIONSHIP BETWEEN THE PYROLYSIS OF TRIMETHYLGALLIUM IN THE GAS-PHASE AND THAT ON THE SURFACE

Trimethylgallium (TMGa) heterogeneously decomposes predominantly at a lower partial pressure than 3×10-3 atm in the presence of GaAs. As the TMGa partial pressure becomes larger, more TMGa decomposes in the gas phase than on the surface. The decomposition mechanism using the Langmuir adsorption isotherm is explained; the TMGa adsorbs on the surface obeying the Langmuir adsorption isotherm and TMGa decomposes on the surface as well as in the gas phase. From this decomposition mechanism the TMGa decomposition rate constant in H2 without the surface catalysis is evaluated as ln kg(s-1) =38.8-57.6 (kcal/mol)/RT.