科研之友
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摘要
The surface structure, electronic properties, lattice dynamics, and the electron-phonon coupling for p-doped diamond (001)-(2 x 1) and (111)-(2 x 1) thin films have been extensively investigated using ab initio methods within the virtual crystal approximation. The calculations of p-doped diamond thin films strongly favor dimer reconstruction of diamond surfaces. The physical origin of superconductivity of diamond (001)-(2 x 1), respectively, and (111)-(2 x 1) thin films which is higher than that of bulk diamond is systematically studied. It is showed that surface vibrational modes of diamond (001)-(2 x 1) surfaces give main contributions to superconducting transition temperature T-c, while T-c of diamond (111)-(2 x 1) surfaces is attributed to the combined action of surface and bulk vibrational modes. Therefore, at the highest concentration (13.98 x 10(21) cm(-3)) T-c approximate to 56.5 K of diamond (111)-(2 x 1) surfaces is about twice as high as that of bulk and diamond (001)-(2 x 1) surfaces.
