A density functional theory study on the gas-phase formation of InGaN by metalorganic chemical vapor deposition

Density functional theory was used to analyze the formation of InGaN from trimethyl indium (TMIn) and trimethyl gallium (TMGa) by metalorganic chemical vapor deposition in ammonia in terms of oligomerization reactions of the nitrides and the elimination reactions of the oligomers formed. The reaction pathways were assumed by reference to previous studies, and their free energy and energy barrier characteristics were calculated for different temperatures. The results indicated that, in the oligomerization reactions, the decomposition temperature of dimers is higher than that of trimers; dimethyl indium nitride (DMInNH₂) is more prone to polymerization than dimethyl gallium nitride (DMGaNH₂); and oligomerization of DMInNH₂ is more likely to occur. In the elimination reactions, when the reaction temperature is high, oligomers tend to generate [MMXNH₂][MMXNH₂] (MM = monomethyl; X  = In or Ga) first by intramolecular elimination, and then generate the stable products [XNHNH₂][XNHNH₂] by intermolecular elimination of NH₃. However, when the reaction temperature is low, [X(NH₂)₃][X(NH₂)₃] is generated by intermolecular elimination.