Two-dimensional B–C–O alloys: a promising class of 2D materials for electronic devices

Abstract

Graphene, a superior 2D material with high carrier mobility, has limited application in electronic devices due to zero band gap. In this regard, boron and nitrogen atoms have been integrated into the graphene lattice to fabricate 2D semiconducting heterostructures. It is an intriguing question whether oxygen can, as a replacement of nitrogen, enter the sp² honeycomb lattice and form stable B–C–O monolayer structures. Here we explore the atomic structures, energetic and thermodynamic stability, and electronic properties of various 2D B–C–O alloys using first-principles calculations. Our results show that oxygen can be stably incorporated into the graphene lattice by bonding with boron. The B and O species favor forming alternate patterns into the chain- or ring-like structures embedded in the pristine graphene regions. These B–C–O hybrid sheets can be either metals or semiconductors depending on the B : O ratio. The semiconducting (B₂O)_nC_m and (B₆O₃)_nC_m phases exist under the B- and O-rich conditions, and possess a tunable band gap of 1.0–3.8 eV and high carrier mobility, retaining ∼1000 cm² V⁻¹ s⁻¹ even for half coverage of B and O atoms. These B–C–O alloys form a new class of 2D materials that are promising candidates for high-speed electronic devices.