Complementary Structural Information from Diffraction Patterns in STEM: Accurate Thickness Measurement with Pattern Matching

Abstract

In this paper, we discuss the advantage of combining STEM imaging with diffraction. in addition, we present a set of accurately calculated convergent beam electron diffraction (CBED) patterns for Si, which highlights the sensitivity of electron diffraction to structure. The calculation takes the full account of crystal bonding by including known experimental structure factors in simulation. Such calculated patterns can be used for accurate determination of the sample thickness, crystal orientation and polarity (for acentric crystals). Calculations with and without crystal bonding show significant difference in calculated intensities, equivalent to a change in thickness about several nanometers for thick samples.The annual dark field (ADF) imaging mode in scanning transmission electron microscopes offers the unique advantage of combining high-resolution electron imaging and spectroscopy with diffraction. The large cutoff angle used in ADF imaging allows simultaneous recording of diffraction patterns for quantitative structural information, while ADF imaging gives the precise position of the probe and the image of the sample.