Figure 3. Cross-sectional morphology of Ge microspheres.

(a–d) TEM images of cross-sectional Ge microspheres by FIB to obtain an ultrathin section. The position of (b) is marked by letter “A,” and the position of (d) is marked by letter “B.” (c) HRTEM image of the cross-sectional Ge microsphere (indicated by the letter “B”). (e) A processed image of the cross-sectional area of the Ge microsphere showing the network structure inside the sphere. (f) A 2-D FFT image of the network structure shown in the cross-sectional area of the Ge microsphere in (d). (g) A schematic illustration of the Ge nanostructure composed of four hexagonal stems (outlined with blue solid lines) with a joint which is in a truncated tetrahedron shape (outlined with green dot lines). One of the four triangular planes is depicted with face color red in order to denote different crystalline plane from the four hexagonal planes.