The rapid progress in LVSEM instrumentation is based on the development of Schottky emission and field-emission guns rather than the thermionic cathodes used in conventional SEM. The smallest electron probe size is limited mainly by the chromatic and spherical lens aberrations, and electron probe diameters of 1-2 nm at 20-30 keV and about 10-20 nm at 0.5-1 keV are attainable. The most efficient detector systems are scintillator-photomultiplier combinations, and semiconductor and microchannel-plate detectors. The improvement of electron optics using in-lens operation and through-lens detection of emitted electrons depends on new detector strategies.
Online access to SPIE eBooks is limited to subscribing institutions.