The effect of line-by-line laser scanning on the properties of laser-induced graphene

Technology of polyimide (PI) film carbonization by direct laser treatment attracts much attention due to the versatility and ease of obtaining the carbon material, laser-induced graphene (LIG), used in the creation of various sensors and functional devices. In this work LIG film structures are obtained by line-by-line scanning of a cw CO$_2$ laser beam over the surface of the PI film. The synthesized carbon film material is studied by optical and scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. It is shown that the Raman spectra of a single LIG line and a set of overlapping LIG lines significantly differ from each other. It is found that multiple laser scanning of the PI film leads to a marked decrease in the number of defects in the LIG structure as well as to a significant decrease in the specific surface resistance of the synthesized film material. The results obtained can be used in the synthesis of LIG film structures with improved characteristics.