Figure 4.

SEM observation of NW sidewalls for (a1) a <111>-oriented Si NWs and (b1) a <110>-oriented Ge NWs grown on a Si(111) surface by MBE. Some sidewall orientations are indicated for both types of NWs. Lattice-resolved TEM images showing the roughness of (a2) a {112} sidewall on a <111>-oriented Si NWs and (b2) a {111} sidewall on a <110>-oriented Ge NWs.