A new dedicated ultra-high-vacuum scanning transmission electron microscope (UHV-STEM) has been developed for the NSF HREM facility at Arizona State University, in conjunction with VG Microscopes Ltd. This instrument is fitted with a specimen preparation chamber in which vacua of better than 5x10-10 mbar can be routinely achieved; the pressure inside the column is better than 10-10 mbar. The initial performance in various imaging modes is reported. Several techniques have been incorporated to obtain information from surfaces. Here we demonstrate the usefulness of biassed secondary electron imaging from both sides of thin transmission samples. In conjunction with conventional STEM imaging and analysis techniques, these methods can be used to correlate surface and subsurface information on samples with complex surface topography. Examples typical of catalytic and semiconductor applications are given.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics