Demonstration of atomic resolution Z-contrast imaging by a JEOL JEM-2010F scanning transmission electron microscope

The collection of atomic resolution Z-contrast images, using an annular dar kfield detector, has until recently been exclusively performed using the de dicated scanning transmission electron microscope (STEM). Here, preliminary results demonstrate the capability of performing this technique with a 200 kV FEGTEM, featuring a Schottky-emission electron gun. As in the dedicated STEM, the microscope's spatial resolution limit, for both Z-contrast imagi ng and chemical micro-analysis experiments, depends on the objective lens s pherical aberration and the source brightness. Images from a number of mate rials indicate sub-2 Angstrom Z-contrast resolution. In addition, the instr ument exhibits probe stability sufficient to observe 1.6 Angstrom lattice f ringes in coherent convergent beam electron diffraction (CBED) patterns. Us ing an electron Ronchigram, a spherical aberration coefficient of 0.5 mm ha s been measured in STEM alignment for one particular pole-piece. Therefore, higher spatial resolution than that observed here may be possible with a f urther optimized instrument.