Group III nitrides, such as GaN, AlN and InGaN, have attracted a lot of attention due to the development of blue-green and ultraviolet light emitting diodes and lasers. A GaN crystal can be grown from the vapor phase by either evaporation of Gallium (Ga) metal or sublimation of GaN powder in ammonia (NH3) atmosphere at a temperature-controlled growth furnace. In this paper, an integrated GaN growth model using a sublimation growth model has been developed based on the conservation of momentum, mass, chemical species and energy together with necessary boundary conditions that account for heterogeneous chemical reactions both at the source and seed surfaces. For the growth rate, the effects of the gas-flow rate, source temperature, temperature difference, and the gap width of the growth cell on the growth process have been studied. (C) 2002 Elsevier Science B.V. All rights reserved.