Boosting the intrinsic carrier mobility of two-dimensional pnictogen nanosheets by 1000 times via hydrogenation

Basal plane functionalization is a versatile method to tailor the physical and chemical properties of two-dimensional (2D) materials. Upon mono-hydrogenation, each pnictogen atom would have four available valence electrons, exactly equivalent to group IV elements, e.g., carbon. Similarly, both structural and electronic properties of hydrogenated pnictogen nanosheets resemble those of graphene, namely, an almost flat basal plane and a Dirac cone-like band structure. However, the presence of spin-orbit coupling would open a gap at the Dirac points of the hexagonal Brillouin zone. As a consequence, mass-less Dirac electrons acquire tiny effective masses. Such tiny effective masses and low electron-phonon coupling strength eventually result in a sharp increase in the carrier mobilities of two dimensional As, Sb, and Bi. Giant carrier mobilities and medium-sized direct band gaps would enable promising applications of 2D pnictogen nanosheets in semiconducting electronics and optoelectronics.