Ultrathin AAO Membrane as a Generic Template for Sub-100 nm Nanostructure Fabrication (original) (raw)
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Ultrathin Alumina Membranes for Surface Nanopatterning in Fabricating Quantum-Sized Nanodots
Small, 2010
Using ultrathin alumina membranes (UTAMs) as evaporation or etching masks large-scale ordered arrays of surface nanostructures can be synthesized on substrates. However, it is a challenge for this technique to synthesize quantum-sized surface structures. Here an innovative approach to prepare UTAMs with regularly arrayed pores in the quantum size range is reported. This new approach is based on a well-controlled pore-opening process and a modulated anodization process. Using UTAMs with quantum-sized pores for the surface patterning process, ordered arrays of quantum dots are synthesized on silicon substrates. This is the first time in realizing large-scale regularly arrayed surface structures in the quantum size range using the UTAM technique, which is an important breakthrough in the field of surface nanopatterning.
2016
Ordered nanostructure arrays are attracting intensive scientific attention because of their many and varied applications. However, it is still a challenge to achieve ordered nanostructure patterning over a relatively large area (for instance on the wafer scale) by a technique that will allow high throughput, large pattern area and low equipment costs. Part of the work reported here is the achievement of facile transferring of ultrathin alumina membranes (UTAMs) which have been attached on wafer-scale substrates without any twisting, folding, cracking or contamination because of the unique design of the fabrication and transferring processes. The crucial element of this method is fixing the prepared 4-inch UTAM onto a wafer-scale substrate before removing the remaining Al and the alumina barrier layer. The thickness and surface smoothing of the UTAMs play a vital role in this process. By using these perfectly transferred UTAMs as masks, various nanostructuring patterns including nano...
Fabrication of ultra thin anodic aluminium oxide membranes by low anodization voltages
IOP Conference Series: Materials Science and Engineering, 2011
Formation of ultrathin anodised aluminium oxide (AAO) membranes with high aspect ratio by Al anodization in sulphuric and oxalic acids at low potentials was investigated. Low anodization potentials ensure slow electrochemical reaction speeds and formation of AAO membranes with pore diameter and thickness below 20 nm and 70 nm respectively. Minimum time necessary for formation of continuous AAO membranes was determined. AAO membrane pore surface was covered with polymer Paraloid B72 TM to transport it to the selected substrate. The fabricated ultra thin AAO membranes could be used to fabricate nanodot arrays on different surfaces.
ACS Nano, 2015
Ordered nanostructure arrays have attracted intensive attention because of their various applications. However, it is still a great challenge to achieve ordered nanostructure patterning over a large area (such as wafer-scale) by a technique that allows high throughput, large pattern area and low equipment costs. Here, through a unique design of the fabrication and transferring processes, we achieve a facile transferring of wafer-scale ultrathin alumina membranes (UTAMs) onto substrates without any twisting, folding, cracking and contamination. The most important in our method is fixing the UTAM onto the wafer-scale substrate before
Nanoporous alumina membrane prepared by nanoindentation and anodic oxidation
Surface Science, 2009
The fabrication of nanopatterned surfaces at large scale attracts the interest of research groups from a wide range of areas as biotechnology, nanoelectronics and nanomagnetism. An extended method to pattern the surface in the nanoscale is the fabrication of ordered arrays of nanoelements based on porous templates as Nanoporous Anodic Aluminium Oxide (NAAO). One of the challenges of the NAAO fabrication, based on self-organized methods, is the control of the symmetry and lattice parameter of the ordered nanoporous films. In this work, we present a combined method based on Atomic Force Microscopy (AFM) nanoimprint and anodic oxidation of Al surface. AFM nanoindentations substitute the first anodization process and even more important, allow us to control the symmetry and the lattice parameter of the ordered arrays. In addition, by using AFM nanoimprint method it is possible to select the region were the ordered alumina grows. We demonstrate that square nanoporous arrays of alumina with lattice parameter of 105 nm can be obtained by this method.
Nanostructures fabrication by template deposition into anodic alumina membranes
Chemical Engineering Transactions, 2009
In recent years, nanostructured materials have attracted growing interest due to their specific properties, which allow application in several fields such as photonics, nanoelectronics, thermoelectronics (Kelsall et al., 2005). For the fabrication of nanostructures, different methods have been proposed. Template synthesis is extremely interesting due to its simplicity and versatility (Martin, 1996). A variety of materials including metals, oxides, conductive polymers, and semiconductors can be deposited within the pores of either polycarbonate or anodic alumina membranes (AAM). The deposition process produces nanotubes (NTs), nanowires (NWs), or nanorods, whose dimensions can be easily controlled by adjusting template pore geometry and deposition conditions (Inguanta et al., 2007a). In this work, different nanostructures of metals (Ni, Cu and Pd), alloys (Co-Sn), and metal oxides (Cu 2 O, CeO 2 , PbO 2 ) have been fabricated, by electrochemical methods (electroless deposition, electrodeposition and displacement deposition), using AAM as template. Ni electroless deposition resulted in the formation of short metal nanotubes (about 5 μm long). Different results were obtained by Ni electrodeposition, performed applying unipolar pulsed voltage perturbations. With a triangular wave, we have fabricated ordered arrays of metal nanowires, whilst with a square perturbation Ni nanotubes were produced. By electrochemical deposition, amorphous Sn-Co nanowires were also obtained. Co content in the alloy, length and crystallographic structure of nanowires varied with the deposition time. Large arrays of aligned copper(I) oxide nanowires were, also, produced by electrodeposition. Two fundamental parameters were studied: potential perturbation and bath composition. We have found that these parameters influence both composition and crystallographic nature of Cu 2 O nanowires. The electrochemical route was also used to fabricate CeO 2 nanotubes from a non-aqueous electrolyte. The results, obtained by Raman spectroscopy, demonstrate that CeO 2 nanotubes are suitable for catalytic applications. PbO 2 nanowires having high aspect ratios were grown by potentiostatic electrodeposition under anodic polarization. Different electrolytic solutions were used in order to obtain nanowires of pure α-PbO 2 , pure β-PbO 2 , or an α + β mixture. In all deposition conditions, perfectly cylindrical wires, having uniform diameters throughout length were obtained. In this paper we describe also a novel method for the fabrication of a regular and uniform array of metal nanowires into anodic alumina membranes. The method is based on the metal displacement deposition realized into template pores by using a special arrangement, properly designed in order to optimize the processes.
Novel Three-Dimensional Nanoporous Alumina as a Template for Hierarchical TiO 2 Nanotube Arrays
Small, 2013
Porous anodic aluminium oxide (AAO), made by electrochemical anodization of aluminium, has been extensively investigated in the past two decades for its widespread applications in the fi eld of nanoscience and nanotechnology. Besides its use as photonic crystals, [ 1 , 2 ] sensors, bio-separators and superhydrophobic supports, [ 5 , 6 ] porous AAO is very likely the most commonly used hard template, which allows fabrication of a broad spectrum of 1D nanostructures. In general, the anodization of aluminium has to be carried out under relatively mild conditions with a chemically or electrochemically polished mirror-fi nished Al surface. Any harsh conditions, e.g., an elevated temperature and/or an increased concentration of electrolyte, a high voltage or a rough Al surface, could cause a very high local current fl ow, eventually leading to a catastrophic 'breakdown' of the substrate. So far, a few attempts have been made in order to avoid a breakdown during an anodization. For instance, Chu et al. found that aged sulfuric acid helps to improve the critical anodizing potential for a breakdown. Lee et al. demonstrated that a pre-anodized oxide layer ( > 400 nm) is able to provide uniform pore nucleation sites and therefore effectively suppresses the breakdown during hard or mild anodization in phosphoric acid (H 3 PO 4 ) at a high voltage (e.g., 195 V). [ 26 , 27 ] Nevertheless, a very smooth, mirror-fi nished aluminium surface as well as a low anodizing temperature are still needed in order to avoid failure of anodization under harsh conditions. Particularly, anodization of Al in H 3 PO 4 at a high voltage still remains challenging. Any surface pits or defects will likely result in a burnt Al foil.
Applied Surface Science, 2021
We propose a two-steps photocatalytic deposition method to synthesize hierarchical Au nano-and microstructures on TiO 2 surface. While the first deposition leads to the formation of flower-like Au microstructures on a highly active TiO 2 thin film, needle-like sharp Au nanostructures are grown on the former Au microstructures after the second deposition. TiO 2 surface decorated with hierarchical Au structures exhibits a superhydrophilic state with a contact angle (CA) below 5°. After the modification of Au-TiO 2 surface by octadecyl-phosphonic acid (ODP)-self-assembly monolayer (SAM), an extreme water-repellency (with CA > 163°) is achieved which retains its stability even after multiple low-high temperature cycles. The spatially controlled photocatalytic decomposition of OPD-SAM on TiO 2 thin film allows a superhydrophilic-superhydrophobic patterning which may open lot of application avenues in microfluidics, oil-water separation including in water harvesting technologies.