Monolayer Cubic Boron Nitride Terminated Diamond (111) Surfaces for Quantum Sensing and Electron Emission Applications.

Monolayer cubic boron (B) nitride (N) terminated diamond (111) surfaces are proposed and investigated using density functional theory. The carbon (C)-N-B-terminated diamond (111) surface with a monolayer coverage of hydrogen and the C-N-B-terminated diamond (111) surface with a monolayer coverage of fluorine [named C-N-B-F-terminated (111) surface] have positive electron affinities (PEAs) with no inter-band gap states and nearly perfect alignment of nitrogen vacancy (NV). Thus, they could potentially be applied in NV-based quantum sensors. The C-B-N-terminated diamond (111) surface with a monolayer coverage of hydrogen [named C-B-N-H-terminated (111) surface], which has negative EAs (NEAs) and an adsorption energy of -3.51 eV, could potentially be employed in electron emission devices. Specifically, C-N-B-F- and C-B-N-H-terminated diamond (111) surfaces have the largest PEA (4.48 eV) and NEA (-4.00 eV), respectively, of any reported diamond surfaces. We also propose a formalism to construct multiple dipole structures on diamond surfaces to yield extremely large EAs.