Figure 4
From: Morphological evolution of Ge/Si(001) quantum dot rings formed at the rim of wet-etched pits
High resolution AFM images of the islands’ morphology evolution. 280 × 280 μm2 and 400 × 400 μm2 AFM images in derivative mode. Evolution of the islands from the thickening of the wetting layer at the rim of the pit in [110] direction (a) to pre-pyramids (b,c,d), truncated pyramids (e,f), full pyramids (g,h,i) and transition domes (i). In order to better use the strain, relaxed WL in the very close vicinity of the pit rim pyramid islands split its symmetry during formation. The additional facets to the {105} ones in panels (g,h,i) are most probably {116} facets (gray arrows). The evolution towards those {116} facets happens in a complex manner through high-index facets. Those might be {9 13 77}, {3 4 26}, and {5 7 40}, but their true shape is almost impossible to determine by means of AFM since their respective facet areas are very small. Note the different length scale in panel (i).