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首页> 外文期刊>Journal of Applied Physics >Probing ultrafast nonequilibrium dynamics in single-crystal SiC through surface nanostructures induced by femtosecond laser pulses
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Probing ultrafast nonequilibrium dynamics in single-crystal SiC through surface nanostructures induced by femtosecond laser pulses

机译：飞秒激光脉冲诱导的表面纳米结构探测单晶SiC中的超快非平衡动力学

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摘要

Ultrafast non-equilibrium dynamics on the surface of a 4H-SiC crystal is experimentally investigated with time-delayed copropagating two femtosecond laser pulse trains of different linear polarizations. Rippled nanostructures are produced by this irradiation, and the alignment "slant" angle of the ripples is related to the polarizations. With varying time delays between the two laser pulses, this slant angle is found to change. In the first 10 ps, the slant quickly rotates in the direction associated with the polarization of the second incident laser pulse, but then abruptly freezes to a steady offset angle. A physical model is proposed to explain the underlying mechanisms. The first laser pulse produces a transient grating-like modulation of the dielectric constant on the surface, with which the second laser pulse interacts. Because competing fast (Auger) and slow (thermal) relaxation processes reduce the initially induced grating's dielectric constant difference, the vector sum of this partially evolved grating with the second laser pulse's interaction results in the observed slant rotation time dependence. This experiment is straightforward, conceptually simple, and utilizes commercial equipment. The time-resolved slanting of the ripple orientation provides an alternative description of the spatiotemporal evolution of a superheated semiconductor surface.
机译：通过时间延迟共传播两个不同线性偏振的飞秒激光脉冲序列，实验研究了4H-SiC晶体表面上的超快非平衡动力学。通过这种照射产生了波纹状的纳米结构，并且波纹的取向“倾斜”角与偏振有关。随着两个激光脉冲之间时间延迟的变化，发现该倾斜角发生了变化。在最初的10 ps中，倾斜沿与第二个入射激光脉冲的偏振相关的方向快速旋转，但随后突然冻结到稳定的偏移角度。提出了一个物理模型来解释潜在的机制。第一激光脉冲在表面上产生介电常数的类似于光栅的调制，第二激光脉冲与该表面相互作用。由于快速（俄歇）和慢速（热）松弛过程的竞争减小了初始感应光栅的介电常数差，因此，这种部分演化的光栅与第二激光脉冲相互作用的矢量和导致观察到的倾斜旋转时间依赖性。该实验很简单，概念上很简单，并且利用了商业设备。波纹方向的时间分辨倾斜提供了过热半导体表面时空演变的另一种描述。

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  • 来源
    《Journal of Applied Physics》 |2017年第12期|123108.1-123108.7|共7页
  • 作者

    Wanlin He; Jianjun Yang;

  • 作者单位

    Institute of Modern Optics, Nankai University, Tianjin 300071, People's Republic of China;

    Institute of Modern Optics, Nankai University, Tianjin 300071, People's Republic of China, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
  • 原文格式 PDF
  • 正文语种 eng
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