Engineering the crystalline silicon surface by femtosecond laser processing in liquid: hierarchical micro/nanostructure and amorphization

摘要： Hierarchical micro/nanostructure surface structures with different spatial characteristics are achieved after irradiation of crystalline silicon via femtosecond (fs) laser pulses (800 nm, 120 fs, 1 kHz) with the sample submerged in ethanol. According to laser pulse energy and fabrication parameters (such as scanning speed and superimposing writing), a characteristic morphology evolution of ovoid-like smooth modified area, ripple-like, wave-like, and coral-like micro/nanostructures is demonstrated, and the underline principle is discussed. The amorphization of fs laser-modified area is verified and investigated by Raman spectroscope. These modified structures have potential applications in sensors, silicon photovoltaic cells, and sterilization.