Another important phenomenon is GSI-IX supplier the sputtering effect. This effect generally impacts the shape and morphology of nanomaterials [13]. During the implantation process, as the collision cascades, induced by incident ions, the atoms of the target material may get enough energy to be ejected out from the target material [14]. On this account, the surface region of the nanowire will be sputtered away. This sputtering effect will be enhanced at low-lying areas, and then the nanowires will become rougher [15]. Figure 1 shows the scanning electron microscopy (SEM) and transmission electron microscopy (TEM)

images of the ZnO nanowires implanted by Er ions (reported by Wang et al.) [16]. Obviously, there are some deep recesses on the surface of the nanowire. In Figure 1e, it is SN-38 in vivo apparent that the host lattice of the ZnO nanowire is repaired after annealing. Stichtenoth et al. [17] researched the Zn-implanted GaAs nanowires; they found that the right-hand side of the nanowire facing the ion beam incident direction had been amorphous, but the farther side was unimpaired. After annealing at 800°C for 30 min, the

ion-implanted GaAs nanowire was fully re-crystallized; Figure 2b shows the dark-field image of the GaAs nanowire implanted by Zn ions and annealing at 800°C. Traditional annealing technologies include rapid thermal annealing and conventional furnace annealing. In general, the annealing temperature ordinarily keeps at two thirds of the melting point of the implanted materials [18]. Lately, Borschel et al. [19] reported that GaAs nanowires implanted by Mn+ 3-oxoacyl-(acyl-carrier-protein) reductase at 250°C remained as single crystalline. However, polycrystalline nanowires were acquired after implantation at room temperature with subsequent annealing. It is noticeable that nanowires need higher implantation fluences to be amorphized compared with bulk materials; this is attributed to the enhanced dynamic annealing effect in nanowires. Figure 1 SEM, TEM, and HREM images of ZnO nanowires. (a) SEM image of ZnO nanowires dispersed on the substrate before ion implantation.

(b) Low-magnification TEM image of the ZnO nanowire before ion implantation. (c) The corresponding high-resolution electron microscopy (HREM) image of nanowire in (b). (d) Low-magnification TEM image of ZnO after Er ion implantation (annealed). (e) The corresponding HREM image of nanowire in (d). Reprinted with permission from Wang et al. [16]. Figure 2 Dark-field TEM images of GaAs nanowires after implantation and annealing. (a) Zn implantation and (b) subsequent annealing at 800°C under arsenic overpressure. The insets in (a) show two corresponding diffraction patterns of selected areas, whereas the diffraction pattern in (b) is taken from the annealed nanowires. Reprinted with permission from Stichtenoth et al. [17]. What is more interesting is that the bending direction can be controlled by the ion species and implant energy [20, 21].