GaN deposition equipment and processes for the fabrication of white LEDs (Light Emitting Diode) using MOCVD (Metal Organic Chemical Vapor Deposition) were numerically modeled to analyze the effects of a reactive gas introduction strategy. The source gases, TMGa and $NH_3$, were injected from a shower head at the top of the chamber; the carrier gases, $H_2$ or $N_2$, were introduced using two types of injection structures: vertical and horizontal. Wafers sat on the holder at a radial distance between 100 mm and 150 mm. The non-uniformity of the deposition rates for vertical and horizontal injection were 4.3% and 3.1%, respectively. In the case of using $H_2$ as a carrier gas instead of $N_2$, the uniform deposition zone was increased by 20%.