Phonon-mediated superconductivity near the lattice instability in hole-doped hydrogenated monolayer hexagonal boron nitride
Takat B. Rawal, Ling-Hua Chang, Hao-Dong Liu, Hong‐Yan Lu, C. S. Ting
Abstract
Employing the density functional theory with local density approximation, we show that the fully hydrogenated monolayer-hexagonal boron nitride (${\mathrm{H}}_{2}\mathrm{BN}$) has a direct band gap of 2.96 eV in the blue-light region, while the pristine $h$-BN has a wider indirect band gap of 4.78 eV. The hole-doped ${\mathrm{H}}_{2}\mathrm{BN}$ is stable at low carrier density ($n$) but becomes dynamically unstable at higher $n$. We predict that it is a phonon-mediated superconductor with a transition temperature (${T}_{c}$) which can reach $\ensuremath{\sim}31$ K at $n$ of $1.5\ifmmode\times\else\texttimes\fi{}{10}^{14}$ holes ${\mathrm{cm}}^{\ensuremath{-}2}$ near the lattice instability. The ${T}_{c}$ could be enhanced up to $\ensuremath{\sim}82$ K by applying a biaxial tensile strain at 6% along with doping at $n$ of $3.4\ifmmode\times\else\texttimes\fi{}{10}^{14}$ holes ${\mathrm{cm}}^{\ensuremath{-}2}$ close to a new lattice instability.