XRD scan, low-resolution TEM, and HRTEM of a selected InAs nanowire array sample. (a) XRD scan of a selected InAs nanowire array sample, confirming the epitaxial relationship between InAs (111) and Si (111) substrate. (b) Low-resolution TEM image of the nanowire. (c) HRTEM image of a portion of the nanowire. The inset of (c) shows the fast Fourier transform of the selected area, which is viewed along the [0–11] direction.