Nanofabrication of integrated magnetoelectronic devices using patterned self-assembled copolymer templates

Bal, M.; Ursache, Andrei; Tuominen, Mark; Goldbach, James T.; Russell, Thomas P.

doi:10.1063/1.1517400

Cited by 71 publications

(41 citation statements)

References 16 publications

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“…[ [4,6] tracketched membranes, [10] and anodic alumina, [10] have already been developed for the fabrication of nanowire arrays. Among these templates, anodic alumina is widely used to fabricate nanowire arrays because of its chemical and mechanical stability and the possibility of producing ideally ordered pore configurations.…”

Section: Methodsmentioning

confidence: 99%

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Ultrahigh Pore Density Nanoporous Films Produced by the Phase Separation of Eutectic Al–Si for Template‐Assisted Growth of Nanowire Array

Fukutani¹,

Tanji²,

Motoi³

et al. 2004

Advanced Materials

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turn changes the effective contrast between the alternating polymer and LC rich layers in the structure. This is a simple and flexible system by which photoresponsive photonic crystals can be fabricated in a single-step process. In addition to the one-dimensionally periodic systems such as those presented here, complex two-and three-dimensionally periodic HPDLC photonic materials could be fabricated [13] with the Azo-LC materials to make dynamic photonic crystals of any structure in a one-step process. Future studies will include fabricating novel photo-optic photonic structures, in addition to probing the ultimate response time of the system, as well as the effects of excitation intensity, wavelength, and azobenzene concentration. ExperimentalHolographic-polymer-dispersed liquid crystal structures containing azobenzene-derived liquid crystals were prepared from a standard prepolymer syrup containing 35 % E7, to which was added an additional 3.5 % BMAB. The preparation of a standard syrup can be found in [10] and [11], for example. The BMAB was synthesized according to [14], and can be commercially obtained from BEAMCo Inc, Winter Park, FL. Sample cells were prepared by placing a small amount of syrup to which a small amount of 8 lm glass spherical spacers were added on indium tin oxide (ITO) coated glass. The resulting cell contains approximately an 8±10 lm layer of photo sensitive syrup between two glass plates. Bragg reflection gratings were prepared using two counter propagating beams incident on the sample cell. This produced a one dimensionally periodic holographic structure with a grating vector perpendicular to the surface of the cell. The initial diffraction efficiency of these gratings was probed at normal incidence and ranged from 45 to 55 %. Control gratings prepared from an identical syrup without BMAB showed diffraction efficiencies of 50 to 55 %. Current studies in bulk have shown that 10 % BMAB in E7 is sufficient to induce an isothermal N±I transition at room temperature [15]. In order to minimize the attenuation of the triggering UV light through the thickness of the sample, it is desirable to use as low a concentration of Azo-LC as is sufficient to observe a complete, isothermal N±I transition. Thus approximately 3.5 % of the weight of the syrup in BMAB was added to the syrup, which constitutes roughly 10 % of the liquid crystal content. A convenient wavelength, 540 nm, was selected for holographic recording such that it did not overlap the cis absorption substantially, which provided for an accurate measurement of the diffraction efficiency.Once recorded, the reflection gratings are characterized in an apparatus which allowed for the introduction of both a UV laser beam (up to 80 mW cm ±2 of 365 nm from and Ar+ laser) and a doubled Nd:YVO 4 CW beam of 532 nm (up to 100 mW cm ±2 ) while the visible transmission spectrum and absorbance at 365 nm are simultaneously recorded. The UV beam was near the peak absorption of the trans conformer of the Azo-LC and produced a discernable change in color ...

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Section: Methodsmentioning

confidence: 99%

“…One-dimensional structures, such as nanowires and nanotubes, have received considerable attention in recent years for their potential application in many fields. [1] Nanowire arrays are particularly attractive for high-density magnetic recording media, [2±4] sensors, [5,6] and thermoelectric devices.…”

Section: Methodsmentioning

confidence: 99%

Ultrahigh Pore Density Nanoporous Films Produced by the Phase Separation of Eutectic Al–Si for Template‐Assisted Growth of Nanowire Array

Fukutani¹,

Tanji²,

Motoi³

et al. 2004

Advanced Materials

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“…The authors also showed that the cobalt nanowire arrays could be extended to other systems such as giant-magneto-resistance devices [202]. Cobalt hexagonal arrays of nanodots with long range order have been created using an asymmetric PS-b-PMMA copolymer in combination with a topographic guide (graphoepitaxy), where the surface was chemically modified with the PS-r-PMMA brush layer to induce preferential ordering.…”

Section: Metals Within Paa Mtfs and Bcps Templatesmentioning

confidence: 99%

Self-assembled templates for the generation of arrays of 1-dimensional nanostructures: From molecules to devices

Farrell

Petkov²,

Morris

et al. 2010

Journal of Colloid and Interface Science

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Self-assembled nanoscale porous architectures, such as mesoporous silica films (MPS), block copolymer films (BCP) and porous anodic aluminas (PAAs), are ideal hosts for templating one dimension (1 D) nano-entities for a wide range of electronic, photonic, magnetic and environmental applications. All three templates offer dimensional scalability and tunability over a wide range, with critical pore sizes for each system well below the 20 nm threshold [1][2][3]. Recently, research has progressed towards controlling the pore direction, orientation and long range order of these nanostructures through so called directed self-assembly (DSA). Significantly, the introduction of a wide range of top-down chemically and physically pre-patterning substrates has facilitated the DSA of nanostructures into functional device arrays. The following review begins with an overview of the fundamental aspects of self-assembly and ordering processes during the formation of PAAs, BCPs and MPS films. Special attention is given to the different ways of directing self-assembly, concentrating on properties such as uni-directional alignment, precision placement and registry of the self-assembled structures to hierarchal or top down architectures. Finally, to distinguish this review from other articles we focus on research where nanostructures have been utilised in part to fabricate arrays of functioning devices below the sub 50 nm threshold, by subtractive transfer and additive methods. Where possible, we attempt to compare and contrast the different templating approaches and highlight the strengths and/or limitations that will be important for their potential integration into downstream processes. ACCEPTED MANUSCRIPT 3 SECTION 1.0: SELF ASSEMBLY AND NANO-ARCHITETCURESThe diversity of self-assembled nanostructures and more importantly, their precise orientation within a thin film (fixed to a substrate) ultimately determines their function and overall application. A large population of research reports to date have focused on identifying these orientations and related periodicities, using x-ray and microscopy tools, as well the development of methods for readily manipulating nanostructures, such as pre-patterning of silicon substrates for the alignment of block copolymers (BCPs) [4] and mesoporous thin films (MTFs) [5] and altering the growth direction of porous anodic alumina (PAA) templates [6]. In this section, a brief synopsis of the mechanisms behind the self-assembly/organisation of each system and highlight nanoscale architectures (and orientations), which are important from a device perspective. Templated mesoporous thin filmsOrdered mesoporous powders were first discovered by researchers at the Mobil Petrochemical Corporation in 1992 and shortly after, sol-gel derived mesoporous silica films were fabricated [1,7].The first series of ordered mesoporous films were reported by Yang et al. in 1996 [8], prepared using initial surfactant concentrations above their critical micelle concentration (CMC). However the films prepared fil...

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“…High-density Bi 2 Te 3 NWs are predominantly synthesized by a number of template-assisted methods using track-etched membranes [20][21][22], diblock copolymers [23,24], or anodized aluminum oxide (AAO) templates [25,26]. Of these, AAO templates have found particularly widespread usage owing to the simplicity and flexibility of their fabrication methods.…”

Section: Introductionmentioning

confidence: 99%

Individual thermoelectric properties of electrodeposited bismuth telluride nanowires in polycarbonate membranes

Chang

Cho

Kim

et al. 2015

Electrochimica Acta

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Nanofabrication of integrated magnetoelectronic devices using patterned self-assembled copolymer templates

Cited by 71 publications

References 16 publications

Ultrahigh Pore Density Nanoporous Films Produced by the Phase Separation of Eutectic Al–Si for Template‐Assisted Growth of Nanowire Array

Ultrahigh Pore Density Nanoporous Films Produced by the Phase Separation of Eutectic Al–Si for Template‐Assisted Growth of Nanowire Array

Self-assembled templates for the generation of arrays of 1-dimensional nanostructures: From molecules to devices

Individual thermoelectric properties of electrodeposited bismuth telluride nanowires in polycarbonate membranes

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