ENERGY-FILTERED CONVERGENT-BEAM ELECTRON-DIFFRACTION IN STEM

Energy-filtered convergent-beam electron diffraction (CBED) patterns were obtained from a 10 angstrom region of the specimen in a scanning transmission electron microscope (STEM) equipped with a digital image-acquisition system. For crystalline silicon, plasmon scattering causes a blurring of the low-order Bragg beams. Significant plasmon intensity was also observed at high angles with an angular distribution duplicating the zero-loss scattering. The plasmon-loss pattern contained a high-order Laue-zone (HOLZ) ring and Kikuchi bands from elastic, phonon, and plasmon multiple scattering. The HOLZ ring intensity relative to the diffuse background was not significantly different from the zero-loss pattern. Quantitative agreement between experimental silicon (100) CBED patterns and patterns calculated by the frozen-phonon technique was achieved. The silicon room-temperature vibration amplitude was determined to be 0.078 +/- 0.002 angstrom as compared with the value of 0.0764 +/- 0.0002 angstrom reported for X-ray measurement [P.J.E. Aldred and M. Hart, Proc. Roy. Soc. (London) A 332 (1973) 223, 239].