Acquisition of a Field Emission Scanning Electron Microscope

点击翻译按钮获取中文摘要

Over the past several years, Stevens Institute of Technology has constructed a modern centralized facility for microstructural characterization. Matching funds are provided to the Institute to purchase a field-emission scanning electron microscope. With this instrument, approximately 50 graduate students 10 faculty at the Institute can attack research problems that they could not address previously. A significant fraction of materials research at the Institute concentrates on ceramics and polymers. Some current problems are the synthesis of nanocrystalline silicon carbide whiskers, the tribological properties of silicon nitrides and the interphase structure in fiber-reinforced polymer composites and in polymer blends. These involve 3-D structures where information gathered by imaging surfaces using scanning electron microscopy is essential. Because they are poor electrical conductors, however, ceramics and polymers do not lend themselves well to high-resolution electron-optical imaging. Morphological information is limited by artifactual structure introduced by conductive specimen coatings. Problems associated with specimen charging can be significantly ameliorated, however, with a field-emission electron-optical system. A field-emission source has a brightness several orders of magnitude greater than traditional thermionic sources and a smaller incident electron energy spread. These features enable SEM imaging of uncoated specimens at low accelerating voltages (-lkeV) while preserving very good resolution (approx. 4 nm). At higher voltages (approx. 30 keV) the resolution can be as high as l nm.