An Interferometric Electron Ruler with Picometer Accuracy in Gauaging Lattice Displacement

Abstract

We report a novel technique to accurately measure interfacial lattice displacement by forming an electron probe close to a specimen in a manner similar to that originally proposed by Gabor to record a hologram. This method is based on the quantitative analysis of the interference pattern of shadow images in coherent electron diffraction. The approach is unique in that there are no adjustable microscope parameters, the contrast is strong even when the fault is viewed edge-on, and a large number of shadow images of the fault corresponding to different Bragg reflections can be studied simultaneously. Since it is an interferometric technique, the spatial resolution of the measurement is not limited by the wavelength of the fast electrons. An accuracy down to 1pm has been demonstrated in measuring the displacement associated stacking faults and grain boundaries in superconductors. It is, to our knowledge, the highest that has been achieved in measurements of displacement vectors.