Phonon-Mediated Superconductivity near the Lattice Instability in Hole-doped Hydrogenated Monolayer Hexagonal Boron Nitride

Abstract

Employing the density-functional theory with local density approximation, we show that the fully hydrogenated monolayer-hexagonal boron nitride (H${}_2$BN) has a direct-band gap of 2.96 eV in the blue-light region while the pristine $\text{h}$-BN has a wider indirect-band gap of 4.78 eV. The hole-doped H${}_2$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 $\sim$31 K at $n$ of $1.5\times$ $10^{14}$ holes cm${}^{-2}$ near the lattice instability. The $T_c$ could be enhanced up to $\sim$82 K by applying a biaxial tensile strain at 6 % along with doping at $n$ of $3.4\times$ 10${}^{14}$ holes cm${}^{-2}$ close to a new lattice instability.

14 pages, main text (4 figures), supplemental material (9 figures)