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Diffraction contrast near heterostructure boundaries—its nature and its application
Author(s) -
Bangert U.,
Harvey A. J.
Publication year - 1993
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/jemt.1070240403
Subject(s) - heterojunction , diffraction , characterization (materials science) , electron diffraction , materials science , optics , lattice (music) , contrast (vision) , condensed matter physics , relaxation (psychology) , electron microscope , tilt (camera) , enhanced data rates for gsm evolution , optoelectronics , physics , geometry , mathematics , computer science , psychology , social psychology , acoustics , telecommunications
Two phenomena of diffraction contrast arising at or near III‐V compound hetero‐structure boundaries are described and quantitatively analyzed. In the first observation α/δ‐fringe contrast at boundaries inclined to the electron beam is discussed. Theoretical fringe profiles are generated according to the theory by Gevers et al. in 1964, which are then compared with experimental profiles. Applications to the characterization of AlGaAs/GaAs and InGaAsP/InP interfaces regarding composition, abruptness, and lattice tilt are presented. In the second study a new and very sensitive characterization technique for the direct determination of the strain in strainedlayer structures is described. The method uses electron microscope images of 90°‐wedges, which exhibit a shift in the thickness contours due to strain relaxation at the edge, and compares these to images which are obtained theoretically by implementing finite element strain calculations in wedges in the dynamical theory of diffraction contrast. The considerable potential of this method is demonstrated on the strain analysis of strained GaInAs/GaAs structures. © 1993 Wiley‐Liss, Inc.