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我们用脉冲宽度120 fs、波长800nm、能量密度从0.1 J/cm2~0.5 J/cm2的激光束照射硅样品和锗硅合金样品表面能够生成各种低维形貌结构。特别是将飞秒激光束散焦至直径为100μm的束斑,并以每秒1000个脉冲照射硅样品表面两秒钟时(能量密度在熔融阈值0.2 J/cm2附近),能生成周期间隔为400nm的浮雕光栅状的一维微结构。我们用飞秒激光与其诱导的等离子体波的相干模型解释了光栅状微结构的形成机理。还发现这种结构有很强的PL发光,PL峰的中心约在719nm处。该飞秒激光加工技术既简捷又稳定,在光学和微电子加工领域应有很好的应用前景。
We can generate a variety of low-dimensional topographic structures by irradiating silicon samples and germanium-silicon alloy samples with a laser beam with a pulse width of 120 fs, a wavelength of 800 nm and an energy density of 0.1 J / cm2 ~ 0.5 J / cm2. In particular, the defocusing of a femtosecond laser beam to a beam spot of 100 μm in diameter and irradiating the surface of the silicon sample with 1000 pulses per second for two seconds (energy density near the melting threshold of 0.2 J / cm 2) 400nm relief grating-like one-dimensional microstructure. We explain the formation mechanism of the grating-like microstructure with the coherent model of the femtosecond laser and its induced plasma wave. Also found that this structure has a strong PL luminescence, PL peak center at about 719nm. The femtosecond laser processing technology is simple and stable, and should have good application prospects in the field of optics and microelectronics processing.