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利用飞秒脉冲激光对单晶硅进行辐照,研究了在不同环境(纯水和空气)和能量密度条件下激光刻蚀过后硅片的光致荧光特性.对于辐照后的硅片,利用了场发射扫描电子显微镜(FESEM)、能谱仪(EDS)、傅里叶红外光谱仪(FT-IR)、光致荧光光谱仪(PL)进行表征.结果显示:在空气中样品表面形成了条纹状微结构,纯水中硅片表面生成了尺寸更小的珊瑚状微结构;激光刻蚀后在硅片表面的生成物主要是SiOx(x<2),在纯水中处理后硅片氧元素的含量接近是空气中的4倍;傅里叶变换红外透射谱中主要为Si—Si键(610 cm-1)和Si—O—Si键(1105 cm-1)的振动;在空气和纯水中激发出的荧光均为蓝光(420—470 nm),在各自最佳激发波长下,纯水中荧光强度比空气中强2到3倍,但是在可见光范围内荧光峰的位置和形状都基本没有发生变化.研究表明:氧元素在光致发光增强上起着重要作用,光致发光最主要是由形成的氧缺陷SiOx(x<2)导致的,生成低值氧化物SiOx的多少决定了发光的强弱.
Single-crystal silicon was irradiated by femtosecond pulsed laser to study the photoluminescence characteristics of silicon wafer after laser etching under different environments (pure water and air) and energy density. For the irradiated silicon wafer, Field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence spectroscopy (PL) were used to characterize the results. The micro-structure, the surface of the silicon wafer in pure water generated smaller coral-like microstructure; the surface of the silicon wafer after laser etching was mainly SiOx (x <2), and the oxygen content of silicon wafer Is nearly 4 times higher than that in air. The Fourier transform infrared transmission spectrum is mainly composed of Si-Si bond (610 cm-1) and Si-O-Si bond (1105 cm-1) Fluorescence in water is blue (420-470 nm), and fluorescence intensity in pure water is 2 to 3 times stronger than in air at the optimum excitation wavelength, but both the position and the shape of the fluorescence peak in the visible range Basically no change.Research shows that: oxygen plays an important role in photoluminescence enhancement, photoluminescence is mainly caused by The formation of oxygen defects SiOx (x <2) led to the formation of low-value oxide SiOx how much determines the intensity of light emission.