Contrast mechanisms of secondary electron images in scanning electron and ion microscopy

The contrast of secondary electron images of scanning electron microscopy SEM.are compared with that of scanning ion microscopy SIM.for metals. The dependence of the secondary electron yields on atomic number in SEM is opposite to that in SIM. The secondary electron yields for electron bombardment increases with atomic number for metals, while those for ion bombardment decreases with increasing atomic number. The origins of those phenomena are discussed on the basis of the range profiles of both particles respect to the surface. q1999 Elsevier Science B.V. All rights reserved