Measurement of mean free paths for inelastic electron scattering of Si and SiO2
Measurement of mean free paths for inelastic electron scattering of Si and SiO2
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DOI：
10.1093/jmicro/51.3.143
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发表时间：
2002-01-01
期刊：
影响因子：
--
通讯作者：
Shindo, D
中科院分区：
文献类型：
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作者：
Lee, CW;Ikematsu, Y;Shindo, D
加速电压和收集角对所有非弹性电子散射的平均自由程（λ（p））的影响，这是一个重要的参数，用于确定试样厚度，通过使用电子能量损失谱，与结晶Si和非晶SiO2进行了研究。首先，Si膜的厚度用会聚束电子衍射法测量，而SiO2颗粒的厚度由它们的球形估算。通过改变加速电压（100 ~ 300 kV）和散射电子的收集角，从电子能量损失谱中计算了Si膜和SiO2粒子的λ（p）。在无物镜孔径条件下，Si膜和SiO_2粒子的λ（p）随加速电压的增加而增加，在300 kV时分别为180 ± 6 nm（Si）和247 ± 8 nm（SiO_2）。此外，发现在两种情况下，在小于25 mrad的范围内，λ（p）随着收集角的增加而急剧减小，而在200 kV下，在收集角大于25 mrad时，λ（p）趋于取恒定值。
The effects of accelerating voltage and collection angle on the mean free path for all inelastic electron scattering (lambda(p)), which is an important parameter for determining specimen thickness by using electron energy-loss spectroscopy, were investigated with crystalline Si and amorphous SiO2. First, thickness of Si film was measured with the convergent-beam electron diffraction method, while thickness of SiO2 particles was estimated from their spherical shape. Then from electron energy-loss spectra, lambda(p) was evaluated for Si film and SiO2 particles by changing the accelerating voltage (100similar to300 kV) and the collection angle for the scattered electrons. Under the condition of no objective aperture, lambda(p) for Si film and SiO2 particles was found to increase with the increase of accelerating voltage and to take values of 180 +/- 6 mn (Si) and 247 +/- 8 nm (SiO2) at 300 kV. Also, it was found that lambda(p) in both cases decreases drastically with the increase of collection angle in the range smaller than 25 mrad, while it tends to take a constant value at the collection angle larger than 25 mrad at 200 kV.