First-principles calculations of electric field (E-field)-driven superconductivity at the hydrogenated diamond (110) surface are presented. While the hydrogens on the surface effectively maintain the intrinsic sp 3 covalent nature of diamond, the hole carriers induced by an external negative E-field lead to a metallic surface region. Importantly, the concentration of hole carriers, confined within a few carbon-layers of thickness ∼5-10Å below the surface, exceeds 10 21 cm −3 , which is larger than the critical hole density responsible for superconductivity in the boron-doped diamond, while the calculated electron-phonon coupling constants are comparable in magnitude, suggesting the possibility of superconductivity with enhanced critical field.

To investigate electric-field-induced superconductivity in covalent semiconductors, band structures and inducedhole carrier density of hydrogenated Si(110) surface in an external electric field were calculated by using first principles full-potential linearized augmented plane-wave method. Results predict that the induced-hole carriers, which form a Fermi surface with a hole pocket centered at Γ point, are less than the critical density of superconductivity for boron-doped Si. Thus, electric-field-induced superconductivity at Si(110) surface may be difficult to achieve, which is in contrast to the case of diamond(110) surface.