Chemical reaction-transport model of oxidized diethylzinc based on quantum mechanics and computational fluid dynamics approaches

Abstract

We developed and studied a chemical reaction-transport model for the production of zinc oxide (ZnO) with diethylzinc (DEZn) and oxygen (O₂). It was confirmed that a large number of ZnO particles were generated during the growth process by testing the internal particles of the cavity by X-ray diffraction. The formation of Zn₃O₃ in the gas phase reaction was simulated using density functional theory, and the effect of nucleation and formation of nanoparticles on the growth of the films was revealed. We also speculate that the adsorption of Zn-containing gas on the wall is the main route by which a ZnO film is formed. The mechanism calculated by quantum chemistry was applied in computational fluid dynamics (CFD) simulations using Fluent14.0 software, and the concentration distribution and gas reaction path of the reaction chamber were calculated and analyzed. Finally, a 9 gas phase reaction model and an 8 surface reaction model were established. Together with the transport model, a complete chemical reaction-transport reaction model was constructed for the ZnO-MOCVD cavity. The validity of the model was verified, and the optimum temperature range of DEZn and oxygen-stabilized growth of ZnO films was determined to be 673-873 K. Using the results of the chemical reaction transport model, the geometry and operation parameters of the reactor can be optimized to improve the characteristics of the epitaxial layer.

Fig. 1. Nanoparticles in the ZnO–MOCVD reaction chamber and the XRD spectra of the ZnO particles.

Fig. 2. (a) Different reaction paths for oxygen to attack on DEZn and their corresponding (b) energy barriers scenarios.

Fig. 3. The potential energy surface (PES) profile of the favourable reaction paths for the reaction Zn(C₂H₅)₂ + 3O₂ → Zn(OH)₂ + 2C₂H₄. Energies are in kcal mol⁻¹ and distances are in angstrom. The reaction paths on triplet and singlet PES are illustrated in blue and red line respectively. The spin conversion point is illustrated in green line and denoted as CP.

Fig. 4. The potential energy surface (PES) profile of zinc hydroxide dehydration computed at B3LYP/6-311G(d) (black) and CCSD(T)/6-311+G(d,p) (red) levels of theory. The relative electronic energies are given in kcal mol⁻¹ while the bond lengths are given in angstrom.

Fig. 5. (a) Simulation model diagram of ZnO–MOCVD reaction chamber (b) two-dimensional flow diagram.

Fig. 6. (a) Normalization results of CFD simulations (b) Arrhenius plots of the growth rate versus reciprocal temperature in literature.

Fig. 7. Temperatures and mass fractions of the main component along the chamber radius.

Fig. 8. Schematic illustration of the chemical reactions in the vapor phase in the MOCVD chamber.