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Illustration of a misfit network after asymmetric strain relaxation in a SiGe stripe on (001) Si. The limitation of the paths of TDs in the direction by the stripe boundary results in a reduced MD density in this compared to the  direction and a correspondingly reduced degree of relaxation in the  direction. By this, the square basis of the tetragonal unit cell of the SiGe crystal is distorted to a rhombic basis of an orthorhombic unit cell in the coordinate system.
(Color online) Channeling angular yield scans of the Ge backscattering signal from stripes measured across (empty circles) and along the stripe (full squares), respectively. The corresponding scan of a cubic Si crystal with its midpoint at 54.74° is shown as reference (star symbols). The insets show the crystallographic directions of the two nonequivalent diagonals with the angles and along the stripe and parallel to the stripes, respectively.
(Color online) Plan view TEM micrograph of an asymmetric MD array in a wide stripe, where the misfit dislocation density perpendicular to the direction of the stripes is about a factor of 2.4 larger than that parallel to the stripes.
Relaxation degrees, , along and perpendicular to SiGe stripes of different widths, together with strains and stresses as well as resistivity changes, , expected to occur in thin Si cap on the SiGe stripes. values are calculated on the basis of piezoelectric measurements on Si (Ref. 10).
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