Electronic and optical characteristics of graphene on the molybdenum ditelluride substrate under the uniform mechanical stress

Abstract

The study presents the effect of opening a semiconductor gap in graphene on the molybdenum ditelluride substrate under mechanical stresses using the density functional theory. It has been shown that uniform compression cannot only open the gap due to graphene sheet deformation but also adjust the gap size depending on the compression strength. The maximum gap found was 0.8 eV when the structure was compressed by 8 %, which is confirmed by further analysis of the UV–vis spectrum. Uniform stretching in contrast does not lead to a significant gap opening. The binding energy of the graphene sheet with the molybdenum ditelluride substrate does not change significantly when mechanical stresses are applied. An additional analysis of the Raman and IR spectra will make it possible to determine the degree of compression of graphene on a molybdenum ditelluride substrate in the experiment. In this case, the corresponding modes mainly correspond to vibrations of carbon atoms in the graphene plane or perpendicular to the substrate. The substrate itself does not make a significant contribution to these vibrational modes.