The scanning low-energy electron microscope: First attainment of diffraction contrast in the scanning electron microscope

Using small Pb crystals deposited in situ on a partially contaminated Si (1 00) crystal, we demonstrate that a commercial scanning electron microscope (SEM) can easily be converted into a scanning low-energy electron microscop e (SLEEM). Although the contrast mechanism is much more complicated them th at in nonscanning LEEM because not only one diffracted monochromatic beam a nd its close environment are used for imaging, but several diffracted beams and a wide energy spectrum of electrons of different origin (secondary ele ctrons, inelastically and elastically scattered electrons) are used, SLEEM is a valuable addition to the standard SEM because it provides an additiona l structure- and orientation-sensitive contrast mechanism in crystalline ma terials, a low sampling depth, and high intensity at low energies.