HIGH-RESOLUTION IMAGING OF SEMICONDUCTOR INTERFACES BY Z-CONTRAST STEM

A new technique for high-resolution electron microscopy is described using a high-angle annular detector in a STEM. The use of highly localized electron scattering gives the images strong chemical sensitivity and many of the characteristics associated with incoherent imaging; there are no contrast reversals with defocus or sample thickness, no Fresnel fringe effects at interfaces, no lateral spreading of lattice fringes, and no contrast from within an amorphous phase. Column by column compositional sensitivity is achieved, even at interfaces, and rigid shifts are independent of thickness and defocus.