Optical conductivity and linear dichroism in monolayer C[formula omitted]N.

We theoretically study the optical properties of monolayer C 3 N within the framework of linear response theory by using a two band effective k ⋅ p Hamiltonian. We find that both the effective masses and optical conductivities are anisotropic arising from the anisotropic band structure at the M point. Although the inter-band coupling only exists in the armchair (x -)direction, the effective mass along the armchair direction is larger than that along the zigzag (y -)direction. Interestingly, the absorption part of the optical conductivity Re σ x x excited by linearly polarized light along the armchair direction is an order of magnitude larger than Re σ y y excited by linearly polarized light along the zigzag direction, resulting in a strong linear dichroism, because the inter-band optical conductivity is dominated by inter-band coupling which only exists in the armchair direction. Finite doping can adjust the optical conductivities i.e., Re σ x x and Re σ y y and modulate the linear dichroism, but the effects of n -type doping and p -type doping are different because of the electron–hole asymmetry. Our results provide further understanding of the electronic state of monolayer C 3 N and maybe useful to design polarized optical devices based on it. • The optical transitions are dominated by electron states at the M point. • The optical conductivities excited by linearly polarized light are highly anisotropic. • Doping can effectively regulate the optical conductivities the linear dichroism. [ABSTRACT FROM AUTHOR]