In this work, the structural, electronic, and mechanical properties of 2D atomically thick diamond (100) nanofilms with surface oxygen functionalization as a function of layer number (n) are investigated by first‐principles calculation. The phonon dispersion curves and ab‐initio molecular dynamics results prove the dynamical and thermal stabilities of the structures at n ≥ 6. The bandgaps of oxidized diamond nanofilms are independent of the layer number, attributed to the main contribution of surface atoms to conductance bands and valence bands near the Fermi energy. The Perdew–Burke–Ernzerhof (PBE) calculations with n from 6 to 22 show that the bandgaps of nanofilms with ether groups on both outmost sides (ether groups on one side and hydrogen functional groups on the other side) are in the region of 1.308–1.838 eV (1.803–1.884 eV). The bandgap values of nanofilms with methoxyacetone groups on both outmost sides (methoxyacetone groups on one side and hydrogen functional groups on the other side) localized in the region of 3.078–3.329 eV (3.135–3.302 eV), and the flat valence bands and conduction bands near the Fermi energy make the easy transition between direct to indirect bandgaps. The calculated elastic constants and acoustic velocities of nanofilms have a significantly parity‐dependent oscillatory phenomenon and increase with increasing film thickness. This work provides new ideas for fabricating 2D diamond‐based nanodevices (i.e., optoelectrical semiconductor devices, micro‐ and nano‐electro‐mechanical systems) with high performances applied in practical fields.

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In this work, the structural and electronic properties of (100), (110) and (111) diamond/c-BN heterostructures are systematically investigated by first principles calculation. The interface between diamond and c-BN shows the weak van der Waals interactions, which is confirmed by the interface distance and interface binding energy. The diamond/c-BN structures are the direct bandgap semiconductors with moderate bandgap values (0.647-2.948 eV). This work helps to promote the application of diamond in electronic and optoelectronic devices.

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