Electronic and optical properties of 2D graphene-like compounds titanium carbides and nitrides: DFT calculations

• Make a revision to the electronic properties of the Tin+1Xn(X=C, N; n=1,2).
• Using FP-LAPW method real and imaginary parts of dielectric function.
• Comparison between the metallic properties of TiN and Carbide compounds.

A first principles study of the electronic and optical properties of the graphene-like Tin+1Xn (n=1,2; X=N,C) has been done in the framework of the Density Functional Theory (DFT) to obtain associated quantities as the dielectric function, energy-loss function, reflectivity and absorption spectra. Results infer to a metallic property, stronger for titanium nitrides than titanium carbides owing to an extra electron in nitrogen atom compared to carbon, as well as a decreasing DOS at the Fermi level as the thickness of the layer increases.The optical studies for horizontal E||x and vertical E||z applied fields at low energies (0–20 eV) reveal a forbidden interval of radiation in the real part of the dielectric function along with a non-zero static dielectric amount at zero energy, exclusively definable for the E||z case of course. But in the imaginary part of the dielectric function some peaks are observed owing to the inter-band transitions. For both types of the applied fields, the plasmonic peaks in the energy loss functions of these compounds indicate a reflectivity of 100% in energies less than 1 eV for E||x case, just in contrast to the E||z.