Fig. 2. (a) Schematics (not to scale) of the final structure of GaAs/GaP SL NWs (with only a few SL segments for simplicity). (b) A 45°-tilted SEM image of GaAs/GaP/SL/GaP NWs with layer thicknesses of 3 nm for GaAs and 3 nm for GaP in the SL. (c) Time evolution of DNW and DNP. The different steps of growth are delimited by dashed lines: the growth of the GaAs stem (step I), the growth of the GaP segment (step II), the growth of the GaAs/GaP SL (step III), and the growth of the top GaP segment (step IV).
