Di-block copolymer directed anodization of hexagonally ordered nanoporous aluminum oxide
(Color online) Schematic illustration of the overall S4VP-guided Al film anodization and Ni nanowires synthesis: (a) spin coating, (b) solvent annealing, (c) surface reconstruction, (d) P4VP residual removal by RIE, (e) Al etching by RIE, (f) PS removal by O2 plasma, (g) Al anodization, and (h) Ni electrodeposition.
SEM micrographs of S4VP thin film. (a) As-spun S4VP and (b) THF-annealed S4VP film on Al thin film. Inset shows higher magnification image of (b). The specimens were immersed into ethanol for 20 min to develop the porous structure prior to SEM observation.
(Color online) SEM micrographs of S4VP film after RIE process. (a) RIE I: Residual P4VP etching located at the bottom of the pores. Bright spots reveal Al underneath porous S4VP film (b) RIE II: Selective Al etching exposed to the surface. Dark spots inside bright rims reveal bare Al indents created by RIE process. (c) Schematics in the left and right panels represent RIE processes conducted in (a) and (b), respectively.
SEM micrographs of AAO anodized at 19.4 V in 2.5 M sulfuric acid: (a) top view of as-prepared AAO without S4VP guidance (ref.), and (b,c) top and tilted view of S4VP directed self-assembly, respectively.
Electrodeposited ∼30 nm diameter, 1 μm tall NiNWs (a) confined into AAO nanopores (cross-sectional view on fracture surface) and (b) liberated nanowires from the AAO template removed by selective chemical etch in 1 M NaOH (aq.).
(Color online) Magnetic hysteresis loop measured out-of-plane (black open squared line) and in-plane (red solid circled line) direction, respectively.
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