Fig. 3

SEM, diameter-time, length-time, and growth mechanism. SEM images show the length and diameter of GaAs NWs with varied growth time, for (a) 15, (b) 30, (c) 45, and (d) 60 min. e, f Varied growth time vs the relationship of diameter and growth length, respectively. g–j The schematics illustrating the growth of Au-catalyzed GaAs NWs : g the Au film annealed to form Au drops, h Au drops alloy with Ga to produce the AuGa _x alloy catalyst, and i the segregation of Ga out of the AuGa _x catalyst can be achieved as the AuGa _x alloy catalyst reaches a supersaturation condition. j Form the axial growth of GaAs NWs