Figure 7

Ordered Ge nanostressors on SiNMs cut into ribbons. (a) Scanning electron micrograph of rows of pure Ge QDs on approximately 20-nm thick, approximately 80-nm wide Si(001) nanoribbons cut along [110] and tethered on both ends. The dots are clearly ordered and separated by approximately 150 nm on each surface. (b) Schematic diagram of dot ordering on the two surfaces of the ribbon. (c) Scanning electron micrograph of the relationship between nucleation on the top and on the bottom surfaces of a ribbon; 8-nm high, 80-nm base width Ge QDs on the top surface (left) and on the bottom surface (right). The Si ribbon is sufficiently thin so that a SEM images both sides simultaneously. When the electron beam is incident on the sample at a large angle with respect to the surface normal, the geometric projection of a nanocrystal on top (left) and bottom (right) surfaces of a Si membrane is different, and the two types of QDs can be distinguished. (d) SEM micrograph of a set of nanoribbons showing global bending caused by the average strain of the QDs. From ref[29].