Structure of Bismuth Telluride Nanowire Arrays Fabricated by Electrodeposition into Porous Anodic Alumina Templates

Sander, Melissa; Gronsky, R.; Sands, Timothy D.; Stacy, Angelica M.

doi:10.1021/cm0207604

Cited by 168 publications

(119 citation statements)

References 40 publications

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“…There is an abundant amount of published papers relating to deposition of metallic nanowires within PAA with targeted applications ranging from arrays of interconnects [170], magnetic and memory devices [171][172], bio-and chemical sensing based on surface enhanced Raman scattering (SERS) [173] and wave guides [174] to thermoelectric and superconductive devices [175].…”

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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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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“…Often, researchers take this route because nanowires offer a significant advantage because of their uniaxial transport properties and increased surface exposure. 16,17) Even for these cases, it is considerably easy to carry out the performance optimization experiments on the basic thin film versions because thin films are comparatively easy to handle and have relatively few associated experimental factors (such as templates).…”

Section: ¹1mentioning

confidence: 99%

Heat Treatment Effects on Electrochemically Grown Bi<sub>2</sub>Te<sub>3</sub> Thin Films for Thermoelectric Applications

Deb¹,

Isoda²,

Caballero‐Calero

et al. 2012

Mater. Trans.

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Bi 2 Te 3 thin films were grown on a large area of n-Si/Ti/Au substrate by an electrochemical process. The synthesized film sample was cut into four different pieces and each piece underwent different heat treatments for 1 h to optimize their carrier concentration. Heat treatment experiments were performed in an inert atmosphere to prevent oxidation of the films during the treatment. X-ray diffraction showed an increase in the crystallite size with increasing annealing temperatures, which affected the thermoelectric performances of the films. At room temperature, the Seebeck coefficient and electrical resistivity were measured using a custom-built setup. Initially, the measured conductivity appeared to be ntype for all films backed by the metal buffer layer and Si substrate. A simple model that could classify the substrate contribution on the overall transport properties was then developed. The model confirmed that the actual conductivities of the films were p-type, and this was supported by their elemental analysis.

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“…and with reservoirs with different internal degrees of freedom may provide another opportunity to engineer the efficiency of the heat engines and to approach the entropy limit (2 nd law of thermodynamics) more easily. 44,45,46 …”

Section: Electron Group Velocity and Electronic Density Of Statesmentioning

confidence: 99%

Thermoelectric, thermionic and thermophotovoltaic energy conversion

Shakouri

2005

ICT 2005. 24th International Conference on Thermoelectrics, 2005.

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Key characteristics of thermoelectric, ballistic thermionic and quasi diffusive thermionic energy converters are compared. First, the main assumptions used to derive the linear Boltzmann transport equations for electrons are examined and the possibility that a higher order transport coefficient may become relevant is discussed. In the linear transport regime, there is a fundamental trade off between high Seebeck coefficient and high electrical conductivity for bulk materials and for many multilayer structures due to the interplay between electronic density-of-states (DOS) and electron group velocity and also due to the shape of DOS versus energy curve deep inside a band. While low dimensional structures alter the density-of-states, a similar trade off still exists. If large barrier heights and high doping concentrations could be achieved solid-state thermionic energy converters would be able to alleviate this trade off, thereby achieving a very high thermoelectric power factor. For this to occur, the electron transverse momentum perpendicular to heterostructure barriers must not be conserved. This can be achieved with non-planar structures or with embedded nanostructures. Finally, a comparison between thermoelectric/ thermionic devices and thermophotovoltaic energy converters shows a difference in the average energy of the emitted hot carriers due to the difference between electronic and photonic density-of-states in the reservoirs. The use of both electrons and photons from a hot reservoir or the engineering of the reservoir density-ofstates may provide additional means to achieve higher efficiency in energy conversion devices and to approach the limit given by the entropy generation more easily.

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Structure of Bismuth Telluride Nanowire Arrays Fabricated by Electrodeposition into Porous Anodic Alumina Templates

Cited by 168 publications

References 40 publications

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

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

Heat Treatment Effects on Electrochemically Grown Bi<sub>2</sub>Te<sub>3</sub> Thin Films for Thermoelectric Applications

Thermoelectric, thermionic and thermophotovoltaic energy conversion

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