Study of femtosecond laser induced periodic structure on amorphous silicon films and crystallization characteristics

•A femtosecond pulsed laser was used to induce the periodic surface structure of polysilicon on 50 nm thickness a-Si thin films.•By adjusting the laser fluence, scanning speed and polarization, The formation of LIPSS on a-Si thin films was accompanied by the study of its crystallographic variation and potential of the morphology control.•The periodic surface structure of polysilicon was prepared in a large area and uniform, and the color effect was observed in the dark field.•This technology is expected to promote practical applications in areas such as pattern decoration, optical storage and optical anti-counterfeiting. The large area and uniform laser-induced periodic surface structure has a wide range of industrial application potential. The effect of the laser beam scanning velocity and laser fluence on the large-area fabrication of Laser-Induced Periodic Surface Structures (LIPSS), on 50 nm thickness a-Si thin films, is investigated. The results show that the formation and crystallization changes of LIPSS structure are obviously related to the scanning speed and laser fluence. In addition to surface morphology, the crystallinity of polycrystalline silicon can also be controlled by laser parameters. Based on these results, we applied direct laser induced periodic surface structuring to drive the phase transition from amorphous silicon into polycrystalline silicon. And prepare the periodic fringe structure of polycrystalline silicon with good crystallization and regular structure. By changing the polarization direction of the incident laser, the periodic surface structure with specific orientation can be obtained, and the surface of the material can be endowed with significant optical properties. When the prepared polycrystalline silicon periodic structure samples with different orientations are put into dark field microscope, the different color effects of the samples can be observed.