Practical aspects of atomic resolution imaging and analysis in STEM

Abstract

In the scanning transmission electron microscope (STEM), the spatial resolution of experimental images and spectra is determined by the size and stability of the electron probe. Atomic resolution, of 0.2 nm and under, is possible if all experimental parameters influencing probe formation are carefully optimized. Here, the formation and alignment of the STEM probe using electron Ronchigrams is described. Practical examples of probe formation, Z-contrast imaging and electron energy-loss spectroscopy (EELS) are demonstrated on a Schottky field emission, JEOL JEM-2010F microscope. Single crystal Si 〈1 1 0〉 images were used for resolution testing and showed that probe sizes of under 0.14 nm are obtainable. A 36.5° Σ5 tilt grain boundary in nominally iron doped SrTiO 3 was imaged incoherently and analyzed with EELS, using this probe.