Numerical Study and Optimization of GaN Thin-Film Growth by MOCVD Method

Light-emitting diode (LED) is considered as the “green light” of the twenty-first century, and the white high-power LED is mainly achieved by the excitation of yellow fluorescent powder with GaN-based blue light. Therefore, the quality of GaN films directly influences the reliability, light efficiency and durability of the Led devices. In the paper, a coupled model has been developed and applied on the simulation of transport phenomena and chemical kinetics during the GaN growth process by a vertical metal-organic chemical vapor deposition (MOCVD) reactor. The effects of the carrier gas type, gas flow rate, and the disk rotation rate on the species distributions, GaN deposition rate and temperature field are investigated. The results indicate that nitrogen is better than hydrogen as carrier gas in consideration of the GaN deposition rate, and that, at the current range of the growth parameters, fast crystal rotation rate and gas inlet velocity are favorable for the large deposition rate and for the improvement of the averaged growth uniformity. However, the edge effect becomes more critical. The results also show that an intermediate gas inlet velocity and a fast disk rotation rate are better conditions from an averaged evaluation of the deposition rate and growth uniformity. The analyses have provided important guide for a practical GaN thin-film growth.