Figure 2.

SEM images of (a) the n-type SiNWs and (b) the SiNW-based μc-Si:H solar cells. The bottom segment diameters of the SiNWs range from 50 to 200 nm, and their lengths extend about 3 μm. The white circles mark out the indium nanoparticles on top of the SiNWs. The final p-type a-Si:H/i-type μc-Si:H/n-type SiNW structure diameter is about 1.5 μm and rather uniform along its length.