Fig. 2: Structural properties of the studied Ge/Si0.2Ge0.8 QWs.
From: Direct bandgap quantum wells in hexagonal Silicon Germanium
a False-colored HAADF-STEM image of a cross-sectional lamella, viewing the Ge QW along the [0001] zone axis. Inset shows that Ge QWs on neighboring facets have different thicknesses. b Growth rate curve for Ge/Si0.2Ge0.8 QWs. The thicknesses of individual facets, all measured in images acquired along the [0001] zone axis, are indicated with the colored data points. Colored areas show approximate probability distributions, obtained from these data points by Kernel smoothing. c False-colored HAADF-STEM image of a cross-sectional lamella, viewing the QW along the \([11\overline{2}0]\) zone axis. The core of the NW is on the left. Locations with local hexagonal (ABABA, blue), cubic (ABCA, green), and twinned cubic boundary (ABCBA, pink) stacking are indicated with circles. The pink arrow highlights a defect that starts in the Ge QW. d X-ray diffraction reciprocal space map around the hexagonal \([10\overline{1}5]\) reflection. The peak position does not match Vegard’s rule (dashed line), indicating pseudomorphic strain relaxation.
