Abstract
It is well known that femtosecond laser pulses can easily spontaneously induce deep-subwavelength periodic surface structures on transparent dielectrics but not on non-transparent semiconductors.Nevertheless,in this study,we demonstrate that using high-numerical-aperture 800 nm femtosecond laser direct writing with controlled pulse energy and scanning speed in the near-damage-threshold regime,polarization-dependent deep-subwavelength single grooves with linewidths of～180 nm can be controllably prepared on Si.Generally,the single-groove linewidth increases slightly with increase in the pulse energy and decrease in the scanning speed,whereas the single-groove depth significantly increases from～300 nm to～600 nm with decrease in the scanning speed,or even to over 1 μm with multi-processing,indicating the characteristics of transverse clamping and longitudinal growth of such deep-subwavelength single grooves.Energy dispersive spectroscopy composition analysis of the near-groove region confirms that single-groove formation tends to be an ultrafast,non-thermal ablation process,and the oxidized deposits near the grooves are easy to clean up.Furthermore,the results,showing both the strong dependence of groove orientation on laser polarization and the occurrence of double-groove structures due to the interference of pre-formed orthogonal grooves,indicate that the extraordinary field enhancement of strong polariza-tion sensitivity in the deep-subwavelength groove plays an important role in single-groove growth with high stability and collimation.
基金项目
Natural Science Foundation of Guangdong Province(2021A1515012335)
National Natural Science Foundation of China(11274400)
Pearl River S&T Nova Program of Guangzhou(201506010059)
State Key Laboratory of High Field Laser Physics(Shanghai Institute of Optics and Fine Mechanics)()
State Key Laboratory of Optoelectronic Materials and Technologies(Sun Yat-Sen University)()
NETL
NSTL
万方数据