Chemical reaction-transport model of diethylzinc hydrolysis in a vertical MOCVD reactor

Abstract

ZnO thin film has many uses as a semiconductor material. It can be fabricated by chemical vapor deposition with diethylzinc (DEZn) and water vapor. The present study employs density functional theory to examine reaction complexes of DEZn with 1–2 molecules of water, which may occur in the gas phase according to previous studies. The kinetic and thermodynamic data provide a better understanding of the ZnO deposition process. A computational fluid dynamics analysis was carried out using the kinetic parameters to simulate the deposition rate of ZnO in a reaction chamber, showing the dependence of the film growth rate on temperature. The simulation data agreed with the experimental one within 8%, proving the feasibility of the current chemical reaction-transport model of diethylzinc hydrolysis. Furthermore, the fields of the flow, the temperature, the multi-species transport, and the chemical reaction were analyzed. These insights could reveal the reaction kinetics of ZnO thin film fabrication in the metal-organic chemical vapor deposition chamber. The results show that the pathway involving nucleation and growth of oligomers from trimers, and ultimately particle formation, is consistent with the decreased growth rate at increasing temperatures. The maximum growth rate of ZnO film was obtained at 573–773 K when ZnO is grown by DEZn and H2O in a horizontal chamber rotating at high speed. When the temperature is above 773 K, parasitic reactions lead to a rapid decline in the ZnO deposition rate. These insights could reveal the reaction kinetics of ZnO thin film fabrication; and help with the reactor design, optimization, and process parameter adjustment in the metal-organic chemical vapor deposition process.