III–V Nanowires: Synthesis, Property Manipulations, and Device Applications

Figure 2

(a) Single-step growth method. (a1) Schematic illustration of growth mechanism of the single-step method, demonstrating the kinked morphology and surface coating during the NW growth; (a2) SEM and (inset) TEM images of the NWs grown by the single-step method. (b) Two-step growth method. (b1) Schematic illustration of growth mechanism of the two-step method; (b2) SEM and (inset) TEM images of the NWs grown by the two-step method. (c) Crystal defect characterization between the single- and two-step grown GaAs NWs. (c1) Room temperature PL spectra, showing a good crystal quality of the two-step grown NWs, lacking nonradioactive recombination centers; (c2) Raman spectra with a lower LO(Γ)/TO(Γ) peak intensity ratio indicating the existence of arsenic precipitates in the single-step grown NWs; (c3) Cross-sectional view of NWs with the corresponding crystal quality and equilibrium energy band diagram at the zero gate bias. Reproduced from [18, 33] with permission from The American Chemical Society.