Theoretical study of hydrogen-covered diamond (100) surfaces: A chemical-potential analysis

Article

关键词: SATURATED SI(100) SURFACE;    AB-INITIO CALCULATIONS;    C(100) SURFACES;    ELECTRONIC-STRUCTURE;    RECONSTRUCTION;    PSEUDOPOTENTIALS;    CHEMISORPTION;    C2H2;   

DOI  :  10.1103/PhysRevB.55.9975

来源: SCIE

【 摘 要 】

The bare and hydrogen-covered diamond (100) surfaces were investigated through pseudopotential density-functional calculations within the local-density approximation. Different hydrogen coverages, ranging from one to two, were considered. These corresponded to different structures (1x1, 2x1, and 3x1) and different hydrogen-carbon arrangements (monohydride, dihydride, and configurations in between). Assuming the system was in equilibrium with a hydrogen reservoir, the formation energy of each phase was expressed as a function of hydrogen chemical potential. As the chemical potential increased, the stable phase successively changed from bare 2x1 to (2x1):H, to (3x1):1.33H, and finally to the canted (1x1):2H. Setting the chemical potential at the energy per hydrogen in H-2 and in a free atom gave the (3x1):1.33H and the canted (1x1):2H phase as the most stable one, respectively. However, after comparing with the formation energy of CH4, only the (2x1):H and (3x1):1.33H phases were stable against spontaneous formation of CH4. The former existed over a chemical potential range ten times wider than the latter, which may explain why the latter, despite having a low energy, has not been observed so far. Finally, the vibrational energies of the C-H stretch mode were calculated for the (2x1):H phase.

【 授权许可】

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