Tuning the Electronic and Optical Properties of Two-Dimensional Graphene-like C 2 N Nanosheet by Strain Engineering

Using density functional theory, we have studied the structural, electronic and optical properties of two-dimensional graphene-like C2N nanosheet under in-plane strains. Our results indicate that the C2N nanosheet is a semiconductor with a direct band gap of 1.70 eV at the equilibrium state opening between the highest valence band and lowest conduction band located at the Γ point. The band gap of the C2N nanosheet decreases with the increasing of both uniaxial/biaxial strains. In the presence of the strain, we found band shift and band splitting of the occupied and unoccupied energy states of the valence and conduction bands, resulting in a decrease of the band gap. Furthermore, the absorption and reflectance spectra for the C2N nanosheet have a broad peak around 2.6 eV, where a maximum absorption value is up to 3.2×10-5cm-1 and reflectance is about 0.27%. Moreover, our calculations also show that the optical properties of the C2N nanosheets can be controlled by applying the biaxial and uniaxial strains. The obtained results might provide potential applications for the C2N nanosheets in nanoelectronics and optoelectronics.