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.
Leontis et al. Nanoscale Research Letters 2013 8:383 doi:10.1186/1556-276X-8-383