Тип публикации: статья из журнала
Год издания: 2013
Идентификатор DOI: 10.1021/cg3014738
Ключевые слова: Bond cleavage reaction, Chemical vapor depositions (CVD), Coupled-cluster theory, Density functional theories (DFT), Experimental observation, Minimum energy pathways, Post-Hartree-Fock methods, Quantum chemical studies, Activation energy, Chemical bonds, Crystal growth, Density functional theory, Gallium nitride, Numerical methods, Phase interfaces, Quantum chemistry, Vapors, Chemical vapor deposition
Аннотация: To elucidate an experimentally observed increase of GaN crystal growth rate in the Ga(I)-graphite-NH3(g) system (Jacobs, K. et al. J. Clyst. Growth 2010, 312, 750-755), a gas-phase chemical model of the chemical vapor deposition (CVD) process was developed in a quantum chemical study. The reaction mechanisms in a gas-phase Ga/HCN/NH3 system were predicted using density functional theory (DFT) and post-Hartree-Fock methods including conventional DFT (B3LYP/cc-pVTZ) and coupled cluster (CCSD/cc-pVTZ) theory levels. Activation and reaction energies were refined with a CCSD(T)/aug-cc-pVTZ//B3LYP/cc-pVTZ composite approach. A relatively modern variant of the coupled cluster theory (ROCCL method) in conjunction with the aug-cc-pVDZ basis set for H, N, and aug-cc-pV(D+d)Z for Ga atoms) was employed to investigate bond cleavage reaction pathways. Reactions in Ga(P-2) + NH3 and Ga(P-2) + HCN gas-phase systems and reactivity of products of the Ga(P-2) + HCN reaction (HGaCN and HGaNC) with both Ga (atomic vapor) and NH3 (reactive diluent gas) were included in the model of the chemical transport. Elementary steps involving newly reported cyclic (HGaCNGa) containing intermediates were considered. The role of HCN as a chemical transport reagent in GaN CVD was established unambiguously. A comparative study of minimum energy pathways (MEPs) for reactions in the Ga/NH3 and Ga/HCN/NH3 systems supported the experimental observation of the GaN deposition rate increase.
Журнал: CRYSTAL GROWTH & DESIGN
Выпуск журнала: Vol. 13, Is. 4
Номера страниц: 1445-1457
ISSN журнала: 15287483
Место издания: WASHINGTON
Издатель: AMER CHEMICAL SOC
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