论文标题
调整收敛角度以达到最佳的茎性能
Tuning the convergence angle for optimum STEM performance
论文作者
论文摘要
扫描透射电子显微镜（Stem）的可实现的仪器性能由入射电子探针的大小和形状确定。实现最佳探针曲线的最重要的光学因素是探针形成孔的半径，它决定了照明的收敛半角度。然而，通常被忽略的是，与此最佳距离的小偏差会降低图像对比度的分辨率和解释性。孔径半径30％的误差可能导致典型晶格间距的2个对比度降低，并且薄层的厚度测量（例如栅极氧化物）的厚度测量值5。从对探针形成条件的波光考虑以及讨论的后果进行了理论计算，从波光的考虑来看。然后引入了收敛角度测量和调整的实验方法。 这是针对未校正的电子显微镜。对于校正的仪器，CS = 0，CC通常确定孔径的选择 - 例如超显镜108，（2008）1454-1466
The achievable instrumental performance of a scanning transmission electron microscope (STEM) is determined by the size and shape of the incident electron probe. The most important optical factor in achieving the optimum probe profile is the radius of the probe-forming aperture, which determines the convergence semi-angle of the illumination. What is often overlooked however is that small deviations from this optimum can degrade both the resolution and interpretability of image contrast. A 30% error in aperture radius can lead to a factor of 2 contrast reduction in typical lattice spacings, and a 5 Å error in the thickness measurement of thin layers (such as gate oxides). Theoretical calculations of the optimum convergence angles, from a wave-optical consideration of the probe forming conditions, are explained and their consequences discussed. An experimental approach to the measurement and tuning of the convergence angle is then introduced. This is intended for uncorrected electron microscopes. For corrected instruments, Cs=0, and Cc usually determines the choice of aperture - see e.g. ULTRAMICROSCOPY 108, (2008) 1454-1466
