Abstract Based on the density functional theory (DFT), we theoretically investigate the growth mechanism of GaN (0001) using the Metal-Organic Vapor-Phase Epitaxy (MOVPE). We first identify the structure of the… Click to show full abstract
Abstract Based on the density functional theory (DFT), we theoretically investigate the growth mechanism of GaN (0001) using the Metal-Organic Vapor-Phase Epitaxy (MOVPE). We first identify the structure of the growing Ga rich GaN (0001) surface, then study the adsorption of NH x (x = 0–3) on such surface. We find that NH 2 and NH units spontaneously intervene in the Ga-Ga weak bonds on the Ga-rich GaN (0001) surface. A reaction pathway of decomposition of NH 3 on Ga rich surface is revealed. During reaction, N is found to incorporate in the weak Ga-Ga bond and form – Ga – (NH) – Ga – structure. The activation barrier of NH 3 is surprisingly small, just 0.63 eV. We also explore the decomposition of NH 2 to N to form Ga-N network and find the plausible reaction pathway with the energy barrier of 2 eV. Taking into account the chemical potential of an H 2 molecule in the gas phase at the growth temperature, we find that this reaction can be overcome. This NH 3 decomposition mechanism and the N incorporation on GaN is a new growth mechanism catalyzed by the growing surface.
               
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