Figure 5
SEM images of PtSi-catalyzed Si NW grown at 800°C for 10 min with different HCl partial pressures: (a) no HCl, (b) P HCl = 40, (c) P HCl = 100, (d) P HCl = 160 mtorr. Mean aperture angles (A) have been measured at the tip of the NW for each sample: (a) A = 14.4°, (b) A = 6.6°, (c) A = 3.4°, and (d) A = 2.7°. The aperture angle decreases when P HCl increases, which implies that the tapering effect is considerably reduced using gaseous HCl.