Superconductivity of p-type diamond (001) and (111) thin films:Ab initio calculations

摘要

The surface structure, electronic properties, lattice dynamics, and the electron-phonon coupling for p-doped diamond (001)-(2×l) and (111)-(2×1) 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 )-(2×1), respectively, and (111 )-(2 × 1) thin films which is higher than that of bulk diamond is systematically studied. It is showed that surface vibrational modes of diamond (001)-(2×1) surfaces give main contributions to superconducting transition temperature T_c, while T_c of diamond (111)-(2×l) surfaces is attributed to the combined action of surface and bulk vibrational modes. Therefore, at the highest concentration (13.98 × 10~(21) cm~(-3)) T_c≈56.5 K of diamond (111 )-(2 × 1) surfaces is about twice as high as that of bulk and diamond (001 )-(2 × 1) surfaces.