In this work, we investigate GaN(0001) crystal growth focusing on gas-phase and surface reactions from the viewpoint of metalorganic chemical vapor deposition (MOCVD) by ab initio calculations. We consider the adsorption of compounds of Ga and N atoms on a Ga-covered surface cluster model. For the adsorption of these compounds, it is found that Ga–Ga bonds undesirable for the steady growth appear for alkylgallium with amino group, and the compounds which have coordinate bonds with NH3 can be a solution for this problem, since they do not make Ga–Ga bonds.

GaN surfaces show several types of the surface growth depending on the surface structures. In this study, we have simulated some kind of initial states of GaN surface growth from the viewpoint of metal-organic chemical-vapor deposition (MOCVD). It is clarified that NH 3 molecules and N radicals can not fully terminate the (0001) Ga surface, and that chemical reactions between trimethylgallium and NH 3 in gas-phase is desirable to some extent because the products which contain GaN cores are immediately stabilized on the GaN(0001) surface.1 Introduction III-V nitride semiconductors have attracted much attention to be applied to several devices, light-emitting diodes, laser diodes, and photo detectors, during these 20 years [1,2]. A lot of trials and errors have been examined to fabricate GaN single crystal to satisfy the industrial requirements, although eliminating the defect concentrations is not easy. It is known that GaN surfaces show several types of the growth mechanism caused by the surface stability different between Ga and N surfaces [3]. In our previous studies, we discussed the parasitic reactions of trimethylgallium (TMG) and trimethylaluminum (TMA) in gas phase which disturb the growth of GaN and AlGaN single crystals [4,5]. Furthermore in this work, we investigate the growth mechanism of GaN single crystals from the view point of metal-organic chemical-vapor deposition (MOCVD) and analyze the relationship between the gas phase and surface reactions.

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