ACCURATE MEASUREMENTS OF CRYSTAL-STRUCTURE FACTORS USING A FEG ELECTRON-MICROSCOPE

An experimental procedure for the accurate measurement of crystal stru cture factors is described. This procedure is based on the use of a fi eld emission gun electron microscope equipped with a Gatan Imaging Fil ter (GIF) system. The slow-scan CCD camera of the GIF system is first characterized and a constrained least squares restoration scheme is us ed for the deconvolution of the experimentally recorded raw elastic CB ED patterns. The procedure has been applied for the accurate measureme nt of the (111) and (222) structure factors of silicon single crystal. A residual chi(2) value of 2.87 is achieved and the determined struct ure factors agree well with previous measurements using X-ray and elec tron diffraction techniques. (C) 1997 Elsevier Science Ltd. All rights reserved.