Papers by Keyword: Self-Assembly

Abstract: A post-drying thermal annealing method is proposed to successfully fabricate micro-/nanostructures with 9,10-diphenylanthracene (DPA). Through varying operating temperature, different morphologies from 0-D to 3-D of pure DPA self-assembly were achieved and studied by SEM, XRD and PL spectra. The morphology transformation mechanism was also investigated. These results indicate that varying annealing temperature is an effective way to control the supramolecular architectures of DPA. In addition, such in situ fabrication on a substrate will provide possibility for manufacture of electronic devices which normally require surface deposition of nanomaterials.

Abstract: We reported here a convective assembly process for the formation of large-area self-assembled monolayers of silica microspheres on silicon and glass substrates. Uniformly coated monolayers of silica spheres were achieved on silicon wafers with and without coated SiN₂ of 3 inch of diameter and large glass substrate of 6 × 6 in² in size. The coating of large-area uniform monolayers of silica microspheres was characterized with scanning electron microscopy and optical microscopy. The mechanism of the convective assembly has been explained by the convective flux that is generated by capillary immersion force caused from the solution evaporation and hydrodynamic drag force. The patterns of silica microspheres were transferred to the silicon substrates using a deep reactive ion etching technique. It is found that textured silicon reduced the reflectance of silicon substrate from 52.2% to 33.2% around 400 nm and from 33.9% to 19.5% around 1,100 nm. The rapid self-assembled monolayer with silica microspheres provided a glimpse at the wide range of coating and photonic device applications where convective assembly can be used.

Abstract: This study produced a regularly arranged membrane, called anodic aluminum oxide (referred AAO), by mean of anodic oxidation treatment. The structure of AAO can be molecular self-assembly and its pore size is consistent. Also, the manufacturing process cost is low. These properties make the AAO be a nanotemplate material. This study further created a high quality of nanostructured film by electrochemical mould with the design of electrolyzer. In addition, a uniform nanothin film was grown on the aluminum surface in the stable control of current and temperature according to the conditions of different anode treatment. This film can form a nanopore array which the diameter can be controlled the size ranging from 15 nm to 400 nm. As results, the study can produce nanoporous template for various aperture by mean of anodic oxidation.

Abstract: According to the principle of dynamic quenching a new ON-OFF fluorescent chemosensor for Cu²⁺ ions was designed, this chemosensor was composed of p-tert-butylthiacalix [arene (TCA),sodium dodecyl sulfate (SDS) and perylene through the form of self-assembly in aqueous solution. Addition of Cu²⁺ ions could result in a quenching of the fluorescence emission of perylene inside micelles, which due to intramicellar complex-fluorophore electron-transfer or energy-transfer effects induced by the complexation of TCA with the Cu²⁺ ions.The experimental results indicated that: Under the condition of TCA/perylene was 800/1, SDS concentration was 150mmol/L and pH value above 9, according to the fluorescence quenching ,within a certain range of the concentration of Cu²⁺ ion can be linearly determined.

Abstract: We demonstrate the structural reorganization of microdomain arrays toward the perpendicular orientation of lamellar morphology in high-molecular-weight PS-b-PMMA films using a combinational approach by solvent-vapor and sequential thermal annealing processes. Solvent annealing with a PMMA-selective acetone vapor induced a cylindrical morphology. However, the sequential thermal annealing of block copolymer (BCP) films led to structural reorganization to an equilibrium lamellar morphology, where the lamellar microdomains were oriented to normal to the film surface. This technique suggests an efficient route for directing orientation and structural reorganization of microdomain arrays in the thin films of high-molecular-weight BCP self-assembly.

Abstract: The progress of information technology has increased the demand of the capacity of storage media. Bit patterned media (BPM) has been known as a promising method to achieve the magnetic-data-storage capability of more than 1 Tb/in.². In this work, we demonstrated fabrication of magnetic nanodot array of CoPt with a pitch of 33 nm using a pattern-transfer method of block copolymer (BCP) self-assembly. Carbon hard mask (CHM) was adopted as a mask to pattern-transfer self-assembled nanodot array formed from poly (styrene)-b-poly (dimethyl siloxane) (PS-PDMS) with a molecular weight of 30,000-7,500 mol/g. According to our experiment results, CHM showed its high selectivity against CoPt in Ar ion milling. Therefore, this result boosted the potential of BCP self-assembly technique to fabricate magnetic nanodot array for the next generation of hard disk drive (HDD) due to the ease of large-area fabrication, and low cost.

Abstract: We investigated the fabrication of self-assembled nanodot array using poly (styrene)-poly (dimethyl-siloxane) (PS-PDMS) block copolymer and its transfer technique as a promising method to fabricate magnetic nanodot arrays for ultrahigh density recording. A carbon (C) layer with a high etch-resistance was especially adopted for magnetic nanodot fabrication. We fabricated PDMS nanodot using PS-PDMS block copolymer with a molecular mass of 11,700-2,900 g/mol. The nanodots were first transferred into silicon (Si) layer and then into C layer on Si substrate by carbon tetrafluoride (CF₄) and oxygen (O₂) reactive ion etching (RIE), respectively. We succeeded in fabricating C nanodots with a diameter of 10 nm and an average pitch of 20 nm.

Abstract: We investigated the possibility of ordering of 12 nm pitced self-assembled nanodots from block copolymer (BCP) improved by the guide pattern with low line edge roughness (LER) for patterned media. We found that LER of the line pattern (σ-value) was reduced by using high-resolution salty development for HSQ resist line pattern fabrication compared with conventional tetramethyl ammonium hydroxide (TMAH) developer. By adopting this development technique to guide pattern fabrication, we demonstrated 10 rows of ordered self-assembled BCP nanodot arrays with a size of 6 nm and a pitch of 12 nm (5 Tbit/in.²) between the guide patterns.

Abstract: A possibility to fabricate nanodot arrays with a dot size of <10 nm="" and="" a="" dot="" pitch="" of="" 12="" along="" guide="" lines="" has="" been="" studied="" for="" ultrahigh-density="" patterned="" media="" in="" magnetic="" recording="" this="" was="" by="" using="" self-assembling="" block="" copolymers="" polystyrene-poly="" dimethyl="" siloxane="" ps-pdms="" electron="" beam="" eb="" drawing="" with="" hydrogen="" silsesquioxane="" hsq="" negative="" resist="" their="" fusion="" method="" it="" demonstrated="" that="" the="" could="" possibly="" achieve="" 6-nm-sized="" nanodot="" arrays="" 10="" 4="" x="" sup="">2 using self-assembling with PS-PDMS of molecular weight 7000-1500 and EB-drawing for narrow guide lines. These results prove that the fusion method is required for achieving extremely small dot arrays as 5 Tbit/in² magnetic storage devices.Keywords: Nanodot, self-assembly, electron-beam drawing, graphoepitaxy, patterned media, magnetic recording.

Abstract: Silica and polystyrene (PS) microspheres assembled on two quite different patterned silicon substrates, cross-like pillar pattern and eye-like pattern, respectively. The results indicated that the surface pattern imposes a predetermined lattice orientation in colloidal crystals (CCs). Other influent factors, such as microsphere size, the altitude of pattern and the concentration of colloidal suspension, may also play an important role on the self-assembly process.