飞秒激光形成的半导体低维结构与发光

Emission of Low-Dimensional Structures Formed by Femtosecond Laser Interaction with Semiconductor

采用飞秒激光辐照硅和硅锗样品,用扫描电子显微镜(SEM)观察样品,发现样品上产生了某些低维结构。用飞秒激光作用产生等离子体相干驻波对硅和硅锗表面的融蚀模型来解释低维结构的形成机制,发现硅的表面周期约为400 nm的光栅结构在波长719 nm处有较强的光致荧光(PL)峰。该光致荧光的发光强度较小,其机制可从激光的脉宽和重复率两个方面来分析。当激光辐照的能量明显超过硅的融蚀阈值时,光栅形状消失,另一种锥状结构开始形成。控制加工条件,可以获得用于衍射和微分束的纳米光栅。

The interaction of ultra-short pulses （120 fs） of laser radiation （800 nm） with Si and SiGe samples was analyzed. Some kinds of low-dimensional structures were found. An ablation model was proposed to explain the effect. It has been noticed that a grating shape in 400 nm period scale occurs on surface of silicon. It is found that the grating of one-dimensional structure has an intensive photoluminescene （PL） whose peak is at wavelength 719 nm. The PL peak is smaller, and its mechanism is analyzed from the pulse width and repetitive rate of laser. When the irradiation energy on silicon increases to exceed the ablation threshold for the grating shape to be broken and a kind of sharp conical structure begins to set up. Controlling preparing condition, a high-quality nano-grating can be made on silicon base for diffracting and micro-splitting of beam.