Figure 2
SEM micrographs of porous versus nonporous SiNWs. Cross-sectional SEM images of (a) porous Si NWs versus (b) nonporous SiNWs. Both are etched for 6 min. In both cases, the length of the SiNWs is small (about 1 μm). The porous SiNWs are fabricated on p+-type Si (resistivity 005 Ω·cm), while the nonporous SiNWs are fabricated on p-type Si (resistivity 1 to 10 Ω·cm). Due to their small length, there is no clear evidence of the presence of an interfacial porous layer between the SiNWs and the Si substrate.