Analysis of the microscopic characteristics of periodic structure arrays on silicon carbide fabricated by femtosecond laser

Abstract

The fabrication of large dimension structures (800 μm × 800 μm) featuring fine and coarse ripple patterns, nano particle structures, and V-shaped grooves was achieved on silicon carbide (SiC) through the use of femtosecond laser. The X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Raman spectroscopy (Raman) were performed on sample surface to investigate the atomic bond, residual stress and lattice disorder. XPS analysis revealed that an increase in laser fluence resulted in an increase in the content of C=O bond, while the content of O–C=O bond decreased. The C–C (sp2) bond was destroyed, while the unstable C–C (sp3) bond increased. Additionally, there was a decrease in the content of Si–Si bond and Si–C bond, and an increase in the content of Si–O bond. The resulting oxide layer contributed to an improvement in the fracture toughness of the periodic array. XRD analysis results indicate that the technique is not sensitive to structural defects in SiC and surface contaminants caused by laser ablation. On the (0008) crystal plane, an increase in fluence resulted in an initial increase in lattice spacing, strain, and residual stress, followed by a plateau. The laser-modified area corresponded to a region of tensile stress, with the maximum tensile stress being 179.464 MPa. On the (0004) crystal plane, an increase in fluence resulted in varying degrees of increase in lattice spacing, strain, and residual stress. The residual tensile stress at the fine ripple and groove bottom was 0 and 14.623 MPa, respectively, while the residual tensile stress at the coarse ripple and nano particle structure was 277.847 MPa. The residual tensile stress increased with an increase in scanning interval. Raman analysis showed that the overall disorder increased with an increase in laser fluence, with a maximum degree of disorder being 0.548.