Improved Growth Kinetic Model for Metalorganic Molecular Beam Epitaxy Using Triethylgallium

An improved growth kinetic model for the MOMBE (metalorganic molecular beam epitaxy) of GaAs and GaSb using TEGa (triethylgallium) is proposed. This model can reproduce simultaneously the experimental curves of the growth rate variation with substrate temperature and group V flux and the desorption rate variation of TEGa and DEGa with substrate temperature, particularly the low-temperature decomposition of TEGa to DEGa. It is found that the decomposition reaction of MEGa to Ga is a rate-limiting process, and that the difference in the growth characteristics between GaAs and GaSb is caused by the difference in the suppression effect of excess group V atoms on the decomposition process of DEGa due to the difference in the desorption parameters of As and Sb. It is also found that the decrease of the growth rate at high temperatures is caused by a rapid increase of the rate constant for the desorption of DEGa and that the nonlinear variation of growth rate with TEGa flux in the intermediate temperature region is caused by the second-order recombination process of MEGa with Et radicals.