Femtosecond laser has been widely utilized for modification of crystal structure to achieve desired functions. So far, however, the effect of crystallographic orientation on the induced structure by femtosecond laser processing has yet been comprehensively studied. The present work is undertaken in an attempt to fill this gap in our knowledge. To this end, commercial-purity Si is used as a target material and high-resolution transmission electron microscopy as well as electron backscatter diffraction are applied to examine the irradiation-induced microstructural changes. The structural response of the pulsed material is found to be principally influenced by the crystallographic orientation of the target surface. Specifically, at the surface orientation close to {111}, a pronounced amorphization effect is observed whereas no disordered material is detected at the orientations close to {100}. This phenomenon could be explained by the lowest crystallization speed required by the (111) surface due to its smallest surface energy. Compared with nanosecond laser, non-thermal melting induced by femtosecond laser induces mild thermal gradient and favors recrystallization.

飞秒激光已被广泛用于修改晶体结构以实现所需的功能。然而，到目前为止，飞秒激光加工对晶体取向对诱导结构的影响尚未得到全面研究。当前的工作是为了填补我们的知识空白。为此，将商业纯度的Si用作目标材料，并应用高分辨率透射电子显微镜和电子背散射衍射来检查辐照引起的微观结构变化。发现脉冲材料的结构响应主要受靶表面的晶体学取向影响。具体而言，在接近{111}的表面方向上，观察到明显的非晶化效果，而在接近{100}的方向上未检测到无序材料。（111）表面所需的最低结晶速度是由于其最小的表面能所致。与纳秒激光相比，飞秒激光引起的非热融化引起温和的热梯度并有利于重结晶。