A dissociated 60 degrees dislocation and its strain fields near a Ge/Si heterostructure interface

摘要

High quality high-resolution transmission electron microscopy image was obtained from a dissociated 60 degrees dislocation near a Ge/Si heterostructure interface. It is observed for the first time that the 60. dislocation dissociates differently from the conventional manner, wherein a 90 degrees 1/3[111] dislocation is generated instead of the 90 degrees Shockley partial dislocation. The strain fields around the 90 degrees and 30 degrees dislocation cores were mapped using the geometric phase analysis technique. Unlike the 90 degrees dislocation, the 30 degrees dislocation has an extremely wide dislocation width, and no evident strain concentration area was found around the dislocation core. After comparing the experimental results with the Foreman dislocation model, the latter, which has a dislocation width related the variable factor a of 0.9-1.5, was determined suitable for the 90 degrees dislocation. Meanwhile, a = 3 to 5 is suitable for the 30 degrees dislocation.