Cross-sectional TEM analysis of laser-induced ripple structures on the 4H-SiC single-crystal surface

The microstructures of femtosecond laser-induced ripples formed on a 4H-SiC single-crystal surface were studied by cross-sectional transmission electron microscopy (TEM), with particular attention on the crystal structure underlying fine and coarse ripples differing in period and morphology. Conventional and high-resolution TEM analyses showed that a continuous amorphous layer approximately 10 to 50 nm thick covers the topmost region of both fine and coarse ripples. These results strongly suggest that the fundamental surface deformation process is common for the entire region of fine and coarse ripples, even though the factors that determine their periods are different.