Electric-field-driven hole carriers and superconductivity in diamond

First-principles calculations of electric-field-driven superconductivity at the hydrogenated diamond (110) surface are presented. While the hydrogens on the surface effectively maintain the intrinsic $s{p}^{3}$ covalent nature of diamond, the hole carriers induced by an external negative electric field $(E$-field) lead to a metallic surface region. Importantly, the concentration of hole carriers, confined within a few carbon layers of thickness $\ensuremath{\sim}$5--10 \AA{} below the surface, exceeds 10${}^{21}$ cm${}^{\ensuremath{-}3}$, 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.