Abstract: Based on the quantum chemistry method, the surface reactions of GaN MOVPE growth were investigated.In particular, the adsorption and diffusion processes of GaCH3 (MMG) on ideal, H-covered and NH2-covered GaN(0001)-plane were calculated and analyzed.By establishing a 3×3 supercell model, the stable adsorption sites, adsorption energies and electron population of MMG on three different surfaces were searched and calculated, and the diffusion energy barriers were also determined.The calculated results show that the stable adsorption sites of MMG are T4 and H3 for all three surfaces, and H3 is slightly more stable than T4.The adsorption energy of MMG on the NH2-covered surface is the largest, that on the H-covered surface is the smallest, and that on the ideal surface is in between.The order of bond strengths between Ga in MMG and the surface adsorbent atoms is Ga-N>Ga-Ga>Ga-H.MMG is less likely to diffuse on the NH2-covered surface than on the ideal and the H-covered surfaces, Therefore, excessive NH2 on the surface inhibits the surface diffusion of MMG.

Key words: Based on the quantum chemistry method, the surface reactions of GaN MOVPE growth were investigated.In particular, the adsorption and diffusion processes of GaCH3 (MMG) on ideal, H-covered and NH2-covered GaN(0001)-plane were calculated and analyzed.By establishing a 3×3 supercell model, the stable adsorption sites, adsorption energies and electron population of MMG on three different surfaces were searched and calculated, and the diffusion energy barriers were also determined.The calculated results show that the stable adsorption sites of MMG are T4 and H3 for all three surfaces, and H3 is slightly more stable than T4.The adsorption energy of MMG on the NH2-covered surface is the largest, that on the H-covered surface is the smallest, and that on the ideal surface is in between.The order of bond strengths between Ga in MMG and the surface adsorbent atoms is Ga-N>Ga-Ga>Ga-H.MMG is less likely to diffuse on the NH2-covered surface than on the ideal and the H-covered surfaces, Therefore, excessive NH2 on the surface inhibits the surface diffusion of MMG.