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

Using density functional theory, we have studied the structural, electronic and optical properties of two-dimensional graphene-like C 2N nanosheet under in-plane strains. Our results indicate that the C 2N 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 C 2N 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 C 2N 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 C 2N nanosheets can be controlled by applying the biaxial and uniaxial strains. The obtained results might provide potential applications for the C 2N nanosheets in nanoelectronics and optoelectronics. © 2018, The Minerals, Metals & Materials Society.