Mechanical and electronic properties of diamond nanowires under tensile strain from first principles

The atomic and electronic structures, heat of formation, Young’s modulus, and ideal strength of hydrogenated diamond nanowires (DNWs) with different cross-sections (from 0.06 to 2.80 nm2) and crystallographic orientations (⟨100⟩, ⟨110⟩, ⟨111⟩, and ⟨112⟩) have been investigated by means of first-principles simulations. For thinner DNWs (cross-sectional area less than 0.6 nm2), preferential growth orientation along ⟨111⟩ is observed. The Young’s modulus and ideal strength of these DNWs decrease with decreasing cross-section and show anisotropic effects. Moreover, the band gap of DNWs is sensitive to the size, crystallographic orientation and tensile strain, implying the possibility of a tunable gap. The effective mass at the edges of the conduction band and valence band are also obtained. These theoretical results are helpful for designing novel optoelectronic devices and electromechanical sensors using diamond nanowires.