Investigation of strain and doping on the electronic properties of single layers of C 6 N 6 and C 6 N 8 : a first principles study.

In this work, by performing first-principles calculations, we explore the effects of various atom impurities on the electronic and magnetic properties of single layers of C 6 N 6 and C 6 N 8 . Our results indicate that atom doping may significantly modify the electronic properties. Surprisingly, doping Cr into a holey site of C 6 N 6 monolayer was found to exhibit a narrow band gap of 125 meV upon compression strain, considering the spin-orbit coupling effect. Also, a C atom doped in C 6 N 8 monolayer shows semi-metal nature under compression strains larger than -2%. Our results propose that Mg or Ca doped into strained C 6 N 6 may exhibit small band gaps in the range of 10-30 meV. In addition, a magnetic-to-nonmagnetic phase transition can occur under large tensile strains in the Ca doped C 6 N 8 monolayer. Our results highlight the electronic properties and magnetism of C 6 N 6 and C 6 N 8 monolayers. Our results show that the electronic properties can be effectively modified by atom doping and mechanical strain, thereby offering new possibilities to tailor the electronic and magnetic properties of C 6 N 6 and C 6 N 8 carbon nitride monolayers.