Density functional theory was used to analyze the formation of InGaN from trimethylindium (TMIn) and trimethylgallium (TMGa) by metalorganic chemical vapor deposition in ammonia in terms of the reaction between trimethyl compounds and NH3, as well as the subsequent reactions of the key amino species DMInNH2. The calculation model is established in GAUSSIAN 09, and the results obtained by the calculation model are proved to be reliable by comparing with the previous research results. Reaction pathways were assumed and the Gibbs free energy and activation free energy calculation were conducted at different temperatures. TMIn and TMGa can undergo adduct reactions with the first NH3 molecule at reaction temperatures below 596 K and 465 K, respectively, but they cannot further react with the second NH3 molecule to form additional products. The temperature range for adduct reactions between TMIn and NH3 is wider compared to TMGa and NH3. In the absence of H radicals in the reaction chamber, DMInNH2 does not undergo spontaneous CH3 radical elimination reactions or CH4 elimination reactions. Instead, DMInNH2 is more inclined to undergo dimerization reactions and CH4 elimination reactions with NH3, leading to the formation of subsequent products, In(NH2)3 and dimers. However, in the presence of H radicals in the reaction chamber, H radicals can facilitate the CH3 radical elimination reaction of DMInNH2 and also promote the NH2 radical elimination reaction of In(NH2)3, In(NH2)2 and InNH2, enabling these reactions to occur spontaneously within the studied temperature range. Consequently, the subsequent products of DMInNH2 become indium atoms and dimers.
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