Gas-Phase Chemical Reaction Mechanism in the Growth of AlN during High-Temperature MOCVD: A Thermodynamic Study

We presented a comprehensive thermodynamic study of the gas-phase chemical reaction mechanism of the AlN growth by high-temperature metal-organic chemical vapor deposition, investigating the addition reactions, pyrolysis reactions, and polymerization of amide DMANH2 and subsequent CH4 elimination reaction. Based on the quantum chemistry calculations of the density functional theory, the main gas-phase species in different temperature ranges were predicted thermodynamically by comparing the enthalpy difference and free energy change before and after the reactions. When T > 1000 °C, it was found that MMAl, (MMAlNH)2, and (MMAlNH)3 are the three most probable end gas products, which will be the main precursors of surface reactions. Also, in high temperatures, the final product of the parasitic reactions is mainly (DMA1NH2)2 and (DMAlNH2)3, which are easy to decompose into small molecules and likely to be the sources of AlN nanoparticles.