Atomistic insights into the growth kinetics and surface chemistry of InGaAs in metalorganic chemical vapor deposition

The metalorganic chemical vapor deposition (MOCVD) preparation of InGaAs is the mainstream approach for commercial production, but the atomic-scale microkinetic mechanisms of its growth process remain to be thoroughly elucidated. The existing atomic-level simulations of the complete InGaAs MOCVD growth process are relatively scarce and suffer from limitations such as restricted model sizes and inadequate consideration of multiprecursor cooperative effects. Therefore, this study employs the β₂(2 × 4)-As surface of GaAs(001) as the substrate, selecting trimethylindium (TMIn), trimethylgallium (TMGa), and AsH₃ as the In, Ga, and As sources, respectively. Our research primarily focuses on the surface reaction steps of InGaAs MOCVD, thereby neglecting gas-phase reactions, and assuming that precursor molecules remain intact when adsorbed on the GaAs surface. Based on density functional theory, periodic surface models were constructed to systematically calculate the reaction energies and energy barriers for the adsorption and decomposition of different precursors, both individually and coadsorbed, thereby clarifying the relationship between rate-limiting steps and deposition efficiency. We found mix precursor reduces the barrier of the rate-limiting step by about 0.2 eV compared to the single-precursor case, demonstrating a synergistic relationship in TMGa and TMIn. The results in our study also reveal the physical nature of surface reaction kinetics, defect formation, and impurity control during InGaAs MOCVD growth.