A Practical, Self‐Catalytic, Atomic Layer Deposition of Silicon Dioxide

Bachmann, Julien; Zierold, Robert; Chong, Yuen Tung; Hauert, Roland; Sturm, Chris; Schmidt‐Grund, Rüdiger; Rheinländer, B.; Grundmann, Marius; Gösele, U.; Nielsch, Kornelius

doi:10.1002/anie.200800245

Cited by 135 publications

(132 citation statements)

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“…The The SiO 2 layer deposition followed the method described by Bachmann et al [51] During the development of the Mullite super cycle process, the pulse, exposure, and pump times were adjusted to infiltrate the whole opaline structure. The following times were used for APTES, TMA, H 2 For the inverse opals, first a TMA + H 2 O infiltration process (300 cycles) was performed at 95 °C onto the self-assembled PS beads, which were later burned out in a Muffle furnace in air (0.8 °C min −1 , 500 °C, 30 min), leading to the inverse opal.…”

Section: Methodsmentioning

confidence: 99%

Low‐Temperature Mullite Formation in Ternary Oxide Coatings Deposited by ALD for High‐Temperature Applications

Furlan

Krekeler

Ritter

et al. 2017

Adv Materials Inter

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coatings on geometrically complex substrates, [2][3][4] such as anodic aluminum oxide membranes, aerogels, photonic crystals, and nanorods, with a film thickness control on the Å-scale. Additionally, by combining two or more binary ALD processes in a super cycle ALD process, multicomponent materials can be achieved, such as nanolaminates, doped thin films, and ternary or quaternary oxides. [5] The ability of compositional control of thin films at an atomic level provides the possibility for development of tailor-made atomically mixed systems, pointing to novel materials functionalities.Direct and inverse opals are examples of photonic crystals, which can be manufactured by colloidal self-assembly [6,7] and ALD. [8,9] Its high ordered porosity of interconnects is attractive for a variety of technological applications, such as porous membranes, catalysts, solid oxide fuel cells, and photonics applications. [10][11][12] The 3D periodic arrangement of pores provides a photonic bandgap to these artificial materials, which prohibits the transmission and hence leads to a reflection of electromagnetic radiation in spectral range which is determined by the materials' properties. Specifically, the radiation wavelength, which will be reflected, is influenced by the material microstructure assemble, mono-or multistacked, and also the macropore size. [8,9,[13][14][15] This selective behavior in transmission and reflection might pave the way to effective solar thermo photovoltaic energy conversion devices [16,17] and also next-generation thermal barrier coatings.However, retention of the 3D structure for high-temperature applications remains a significant challenge. [10,18] As the length scales in these porous materials are decreased, as higher is the surface area and specific activity. When exposed to high temperatures, the material's structure may suffer from detrimental morphological changes, such as extensive grain growth, distortion, and eventually destruction of the total periodically organized structure. [9,10] Therefore, this material needs to not only interact with electromagnetic radiation but also have structural stability and keep its function up to high temperatures (usually higher than 1000 °C). The latter fact could be addressed by coating the substrate material with a ceramic oxide that is stable at high temperatures, either by chemical vapor deposition (CVD) [19] or ALD [20] processes.Herein, mullite has been chosen: A ceramic material, which is well known for its stability at high-temperature environments, Atomic layer deposition (ALD) process presents thickness control in an Ång-strom scale due to its inherent surface self-limited reactions. In this work, an ALD super cycle approach, where a superposition of nanolaminates of SiO 2 and Al 2 O 3 is generated by cycling the precursors APTES-H 2 O-O 3 and TMA-H 2 O, is used to deposit thin films with varying ratio of Al 2 O 3 :SiO 2 into silicon wafers and into inverse photonic crystals. The resulting ternary oxide films deposited at low temperature (150 °C) ar...

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Section: Methodsmentioning

confidence: 99%

Low‐Temperature Mullite Formation in Ternary Oxide Coatings Deposited by ALD for High‐Temperature Applications

Furlan

Krekeler

Ritter

et al. 2017

Adv Materials Inter

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“…For a diameter dependent study, the pore diameters of the templates were reduced to 25 nm and 45 nm via atomic layer deposition (ALD) of 5 nm or 7.5 nm SiO2 respectively [39]. For an intermediate size, the templates with 35 nm pore diameter were used without additional coating.…”

Section: Synthesis Of Individual Nanomagnetsmentioning

confidence: 99%

Intra-wire coupling in segmented Ni/Cu nanowires deposited by electrodeposition

Sergelius¹,

Lee²,

Fruchart³

et al. 2017

Nanotechnology

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Segmented magnetic nanowires are a promising route for the development of three dimensional data storage techniques. Such devices require a control of the coercive field and the coupling mechanisms between individual magnetic elements. In our study, we investigate electrodeposited nanomagnets within host templates using vibrating sample magnetometry and observe a strong dependence between nanowire length and coercive field (25 nm to 5 µm) and diameter (25 nm to 45 nm). A transition from a magnetization reversal through coherent rotation to domain wall propagation is observed at an aspect ratio of approximately 2. Our results are further reinforced via micromagnetic simulations and angle dependent hysteresis loops. The found behavior is exploited to create nanowires consisting of a fixed and a free segment in a spin-valve like structure. The wires are released from the membrane and electrically contacted, displaying a giant magnetoresistance effect that is attributed to individual switching of the coupled nanomagnets. We develop a simple analytical model to describe the observed switching phenomena and to predict stable and unstable regimes in coupled nanomagnets of certain geometries.-2 - INTRODUCTIONIn the investigation of nanomagnet assemblies, the focus has mainly been on lithographicallypatterned, planar structures, which can be used as logic devices capable of executing Boolean logic operations [1][2][3][4][5][6][7][8]. Often applications are sought within high density recording, bit patterned media [9][10][11][12] or MRAM devices [1,13], however since the bit size of modern hard disk drives (approx. 20x20 nm²) is already lower than what is achievable with most lithography techniques [14], potential use is limited. Therefore, the use of the third dimension is an appealing approach. Studies on alternating, vertical stacks of magnetic and non-magnetic materials have already been published, in which a three dimensional shift register is investigated, that is capable of storing and shifting several bits of information as solitons within a single column [15][16][17][18][19]. These shift registers are coupled via RKKY interaction and its oscillatory nature allows for an additional degree of freedom in the design of the device, but as a drawback the samples are very demanding with regard to sample quality and purity. A soliton, which is the bearer of information, is a magnetic frustration within a 1D chain of magnetic moments. It is thinkable to induce such a soliton using dipolar coupling instead of RKKY, simply by magnetizing two nanomagnets in the same direction and placing them next to each other (transversal soliton [20]). Another possibility would be to magnetize them in opposing direction and place them in a head-to-head or tail-to-tail configuration (longitudinal soliton, Figure 1). The coupling strength is then defined by the material properties and the distance of both nanomagnets. Such kinds of nanowires can be synthesized within porous anodic aluminum oxide (AAO) templates [21-23] using electro...

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“…In order to passivate the surface of the nanowires, the pores of the alumina template were coated by atomic layer deposition with a SiO 2 shell having a thickness of about 5 nm 59,60 . The multilayered Co-Ni/Cu nanowires were prepared by two-pulse plating from a single bath by using an Ivium…”

Section: Experiments a Sample Preparation And Characterizationmentioning

confidence: 99%

Magnetothermopower and magnetoresistance of single Co-Ni/Cu multilayered nanowires

et al. 2014

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The magnetothermopower and the magnetoresistance of single Co-Ni/Cu multilayered nanowires with various thicknesses of the Cu spacer are investigated. Both kinds of measurement have been performed as a function of temperature (50 K to 325 K) and under applied magnetic fields perpendicular to the nanowire axis, with magnitudes up to -15 % at room temperature. A linear relation between thermopower S and electrical conductivity σ of the nanowires is found, with the magnetic field as an implicit variable. Combining the linear behavior of the S vs. σ and the Mott formula, the energy derivative of the resistivity has been determined. In order to extract the true nanowire materials parameters from the measured thermopower, a simple model based on the Mott formula is employed to distinguish the individual thermopower contributions of the sample. By assuming that the non-diffusive thermopower contributions of the nanowire can be neglected, it was found that the magnetic field induced changes of thermopower and resistivity are equivalent. The emphasis in the present paper is on the comparison of the magnetoresistance and magnetothermopower results and it is found that the same correlation is valid between the two sets of data for all samples, irrespective of the relative importance of the giant magnetoresistance or anisotropic magnetoresistance contributions in the various individual nanowires.

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A Practical, Self‐Catalytic, Atomic Layer Deposition of Silicon Dioxide

Cited by 135 publications

References 20 publications

Low‐Temperature Mullite Formation in Ternary Oxide Coatings Deposited by ALD for High‐Temperature Applications

Low‐Temperature Mullite Formation in Ternary Oxide Coatings Deposited by ALD for High‐Temperature Applications

Intra-wire coupling in segmented Ni/Cu nanowires deposited by electrodeposition

Magnetothermopower and magnetoresistance of single Co-Ni/Cu multilayered nanowires

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