Figure 2
From: Fabrication of Porous Anodic Alumina with Ultrasmall Nanopores
FESEM top view images of ultrasmall nanopores prepared in 0.3 M oxalic acid under 10 V for 30 min and pore-widened in 5 wt% H3PO4 for 5 min (a) and 10 min (b), respectively, c oblique view of (b) and d TEM image of free-standing ultrasmall nanopores prepared in 0.3 M oxalic acid under 10 V for 5 min and pore-widened in 5 wt% H3PO4 for 10 min after removing the un-anodized aluminum and barrier layer