School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Ultramicroscopy. 2018 Apr;187:13-19. doi: 10.1016/j.ultramic.2018.01.004. Epub 2018 Feb 2.
The intensity profiles of backscattered and secondary electrons from a pure Mg sample have shown a variation with sample thickness and acceleration voltage in the range of 5-30 kV, depending on the specimen holder used. The intensities of backscattered electron (BSE) and secondary electron (SE) signals increases with the sample thickness until saturation when using a scanning transmission electron microscopy (STEM) holder with a closed tube below the sample. However the SE signal increases to the maximum and then decreases with the sample thickness when using a transmission Kikuchi diffraction (TKD) holder with no shielding below the sample whereas the BSE signal again increases until saturation. The influence of the holder on the SE signals is caused by the fact that secondary electrons emitted from the bottom surface could be detected only when using the TKD holder but not the STEM holder. The experimental results obtained are consistent with the Monte Carlo simulation results. Application of the magnitude of the SE and BSE signals to measurement of sample thickness has been considered and the BSE image profile shows a reasonably good accuracy.
从纯镁样品中背散射和二次电子的强度分布随样品厚度和加速电压在 5-30kV 范围内变化，这取决于所使用的样品台。使用带有封闭管的扫描透射电子显微镜（STEM）样品台时，背散射电子（BSE）和二次电子（SE）信号的强度随样品厚度增加，直到达到饱和；而使用没有屏蔽的透射菊池衍射（TKD）样品台时，SE 信号先增加到最大值，然后随样品厚度减小，而 BSE 信号再次增加到饱和。样品台对 SE 信号的影响是由于只有使用 TKD 样品台才能检测到底部表面发射的二次电子，而 STEM 样品台则不能。实验结果与蒙特卡罗模拟结果一致。已经考虑了 SE 和 BSE 信号幅度在测量样品厚度方面的应用，BSE 图像轮廓显示出相当好的准确性。
