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We carried out a kinetic analysis of metallorganic vapor phase epitaxy (MOVPE) of GaN to investigate the dependence of the growth rate on the process conditions as a function of residence time of the precursors in the reactor. The wafer was not rotated during growth, allowing us to analyze the thickness profile of the film in the direction of gas flow, and hence the dependence of the growth rate on the residence time. The growth rate is determined mainly by the concentration of the growth species and mass transfer of the growth species to the wafer surface. The growth rate peaked in the flow direction, and the position of this peak could, in most cases, be explained by considering a combination of the linear gas velocity and the time constant for vertical diffusion of trimethylgallium (TMGa) and/or growth species across the NH 3 feed stream to the wafer surface. In some cases this was not possible, indicating that more complex effects were significant. This work is expected to contribute to understanding of the reaction pathways for GaN-MOVPE, and the growth rate data reported here are expected to provide useful benchmarks for growth simulations that combine computational fluid dynamics and reaction models. Gallium nitride (GaN) is a III/V compound semiconductor material with considerable potential for optoelectronic and high-power electronic devices due to its wide bandgap and high breakdown voltage.1-5 For these reasons, GaN is currently used for mass-produced light-emitting diodes (LEDs), lasers, and high-frequency devices. 6-10Metalorganic vapor phase epitaxy (MOVPE) is commonly employed to manufacture GaN films using trimethylgallium (TMGa) and NH 3 as group-III and group-V precursors, respectively. Research into the growth mechanisms involved in GaN-MOVPE in both academic and industrial institutions has found that the reaction chemistry is relatively complicated, consisting of gas-phase reactions followed by surface reactions. [11][12][13][14][15][16][17] This intrinsic complexity of the reactions suggests that it is not straightforward to design optimal reactors for mass production as well as settling the optimal growth conditions via conventional empirical approaches. Therefore, a variety of studies have been carried out with the aim of understanding GaN-MOVPE. Initially, attention mainly focused on identification of intermediate species that are generated from the gas-phase precursors, which contribute to the layer growth. It then became apparent that parasitic reactions in the gas phase resulted in the formation of adducts, even in the non-heated area of the reactor, in addition to those formed in the hot zone in the vicinity of the heated substrate.18,19 Some of these reaction products led to particle formation without contributing to layer growth. [20][21][22] 39 However, a model that can describe the growth behavior consistently in all reactor configurations and for all process conditions remains elusive. This is our concern, and necessitates comprehensive investigation on the behavior of GaN growt...

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