High-quality structures on 4H-SiC fabricated by femtosecond laser LIPSS and chemical etching

The laser-induced periodic surface structure (LIPSS) can be induced on the 4H-SiC by femtosecond laser. However, there is some problems exist during the laser process. For example, the debris induced by femtosecond laser ablation dropped on the sample surface. In this study, the femtosecond laser generated the high-spatial-frequency LIPSS (HSFL) on the 4H-SiC surface. The Raman spectrum was used to measure the HSFL, followed by the chemical etching that removed the oxidation layer. The results showed that the Raman intensity of amorphous SiC (a-SiC) is highly correlated to the etching rate of HSFL. In addition, the high-quality periodic structures were generated on 4H-SiC after the chemical etching process. The period is near the low-spatial-frequency LIPSS (LSFL). Two different morphology of structures is observed by transmission electron microscope (TEM). One is no ablation region, and the other region exists a little ablation with ablation depth around 30–50 nm. These two regions are similar to the energy distribution of the surface plasmon polariton.