Structure and surface termination of ZnO films grown on (0001)- and (112¯0)-oriented Al2O3

Ay, M.; Nefedov, Alexei; Girol, S. Gil; Wöll, Christof; Zabel, H.

doi:10.1016/j.tsf.2005.12.271

Cited by 11 publications

(10 citation statements)

References 29 publications

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“…For the (012) face, the as-deposited film is polycrystalline and the onset of epitaxy occurs after a thermal treatment: the c axis then becomes parallel to the film surface. For both thin and thick films, the starting orientations are (001) zincite ∥ (110) sapphire , (110) zincite ∥ (012) sapphire , and (001) zincite ∥ (001) sapphire and are all in agreement with previous literature. − …”

Section: Discussionsupporting

confidence: 87%

Role of Interfacial Energy and Crystallographic Orientation on the Mechanism of the ZnO + Al₂O₃ → ZnAl₂O₄ Solid-State Reaction: II. Reactivity of Films Deposited onto the Sapphire (001) Face

Suardelli²,

d’Acapito³

et al. 2013

J. Phys. Chem. C

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The initial steps of the reaction between ZnO and (001)-oriented Al 2 O 3 single crystals have been investigated with X-ray diffraction, atomic force microscopy, and Xray absorption spectroscopy at the Zn−K edge starting from 45 nm thick zincite films. The reaction eventually yields the ZnAl 2 O 4 spinel on this interface but via a complex mechanism involving side and intermediate nonequilibrium compounds, the spinel initially forming with a distribution of lattice parameters. Evidence is given of the fact that one of the side compounds has a crystal structure close to that of the Zn 3 In 2 O 6 compound. The results are discussed in the general context of the same reaction on different single-crystal substrates and different film thicknesses.

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Section: Discussionsupporting

confidence: 87%

Role of Interfacial Energy and Crystallographic Orientation on the Mechanism of the ZnO + Al₂O₃ → ZnAl₂O₄ Solid-State Reaction: II. Reactivity of Films Deposited onto the Sapphire (001) Face

Suardelli²,

d’Acapito³

et al. 2013

J. Phys. Chem. C

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“…(2) The epitaxy of this interface is well established. 9,10 (3) There are several technological applications for which ZnO thin films deposited onto Al 2 O 3 are used or studied (for example, applications in optoelectronics, sensors, and catalysis 11À14 ). ( 4) According to previous work by our group, the reaction at this interface eventually yields the spinel, while different (and nonequilibrium) compounds are found with other interfaces.…”

Section: Introductionmentioning

confidence: 99%

“…This reaction has been chosen as an experimental model for the following reasons: In the ZnO/Al 2 O 3 phase diagram, only one stable reaction product is possible, and this is the ZnAl 2 O 4 spinel . The normal spinel structure of the ZnAl 2 O 4 phase (contrary to the inverse spinel structure, for instance) greatly simplifies data analysis and interpretation of the results. The epitaxy of this interface is well established. , There are several technological applications for which ZnO thin films deposited onto Al 2 O 3 are used or studied (for example, applications in optoelectronics, sensors, and catalysis − ). According to previous work by our group, the reaction at this interface eventually yields the spinel, while different (and nonequilibrium) compounds are found with other interfaces Recently, this reaction has been widely employed for producing appealing nanostructures, such as single and multiwall nanotubes. − …”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Reactions in the Solid State: (110) Al₂O₃ + (001) ZnO Interfacial Reaction

Newton

d’Acapito

et al. 2011

J. Phys. Chem. C

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“…Note that the initial electronic state of the ZnO surfaces (e.g., the side surface), which could influence the polarity of the top and bottom portions of NWs, may be generated by the oxygen plasma treatment used to expose the NW tips. 19 From a first-order approximation (see Supporting Information), without considering the polarization and dielectric screening effect, the electric potential (U) created during tension can be calculated from U )…”

mentioning

confidence: 99%

“…Our electrical current measurements (i.e., direction of current flow) shown in Figure a−c indicate that the tops of the ZnO wires (at the polymer−metal contact interface) become increasingly negative as the temperature rises and are positively charged at the other end (Figure a). Note that the initial electronic state of the ZnO surfaces (e.g., the side surface), which could influence the polarity of the top and bottom portions of NWs, may be generated by the oxygen plasma treatment used to expose the NW tips …”

mentioning

confidence: 99%

Matrix-Assisted Energy Conversion in Nanostructured Piezoelectric Arrays

et al. 2010

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We demonstrate an organic/inorganic hybrid energy-harvesting platform, based on nanostructured piezolelectric arrays embedded in an environmental-responsive polymer matrix, which can self-generate electrical power by scavenging energy from the environment. A proof of principle device is designed, fabricated, and tested using vertically aligned ZnO nanowires and heat as the local energy source. The device layout takes advantage of the collective stretching motion of piezoelectric ZnO NWs, induced by the shapechange of the matrix polymer, to convert the thermal energy into direct current with output power densities of ∼20 nW/cm 2 at a heating temperature of ∼65°C. The responsive nature of polymeric matrices to various stimuli makes this nanostructured piezoelectric architecture a highly versatile approach to scavenging energy from a multitude of environments including fluid-based and chemicalrich systems.KEYWORDS Energy-conversion, piezoelectric, ZnO, Si, hybrid nanogenerator, Seebeck effect E ncouraging progress has been made recently in the development of nanowire (NW)-based piezoelectric nanogenerators. [1][2][3][4][5][6][7][8] In fact, exciting results from various groups working on ZnO, poly(vinylidene fluoride) (PVDF), barium titanate (BaTiO 3 ), and lead zirconate titanate (PZT) have shown device architectures with different powering modes including alternating current (ac) 4-7 and direct current (dc). 9 One key limitation, however, of many piezoelectric-based nanogenerators is the requirement of mechanical energy sources (e.g., mechanical vibration or motion) to generate electrical current. This restricts the use of these nanodevices to a general environment where a direct mechanical energy source is available. To activate the motion of nanopiezoelectric materials through alternate energy sources, such as thermal, photonic, and/or chemical, it will be crucial to investigate new methods of coupling the piezoelectric transducers directly to media that can convert a nonmechanical energy source into piezoelectric strain. This capability will enable materials to be submersed in a variety of environments that have both nontraditional power sources such as mechanical vibrations/motion and pressure gradients as well as traditional power sources such as light, heat, and chemical energy.In this work, we report a self-powered platform that relies on the response of a polymeric film to drive the piezoelectric effect in a nanowire array. To test the concept of polymer facilitated mechanical-to-electrical conversion, we chose to study the well-reported ZnO nanowire system that can be grown by different routes including chemical vapor deposition 10,11 or solution-based techniques 12 and embed the NW array in an environmental-responsive organic polymer. 13 In comparison to other ZnO NW-based nanogenerators, the deformation of the ZnO NWs in our devices are not directly induced by external forces, but rather caused by the shape change in the polymer matrix as it responds to external stimuli. With this hybrid appro...

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Structure and surface termination of ZnO films grown on (0001)- and (112¯0)-oriented Al2O3

Cited by 11 publications

References 29 publications

Role of Interfacial Energy and Crystallographic Orientation on the Mechanism of the ZnO + Al₂O₃ → ZnAl₂O₄ Solid-State Reaction: II. Reactivity of Films Deposited onto the Sapphire (001) Face

Role of Interfacial Energy and Crystallographic Orientation on the Mechanism of the ZnO + Al₂O₃ → ZnAl₂O₄ Solid-State Reaction: II. Reactivity of Films Deposited onto the Sapphire (001) Face

Mechanisms of Reactions in the Solid State: (110) Al₂O₃ + (001) ZnO Interfacial Reaction

Matrix-Assisted Energy Conversion in Nanostructured Piezoelectric Arrays

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Structure and surface termination of ZnO films grown on (0001)- and (112¯0)-oriented Al2O3

Cited by 11 publications

References 29 publications

Role of Interfacial Energy and Crystallographic Orientation on the Mechanism of the ZnO + Al2O3 → ZnAl2O4 Solid-State Reaction: II. Reactivity of Films Deposited onto the Sapphire (001) Face

Role of Interfacial Energy and Crystallographic Orientation on the Mechanism of the ZnO + Al2O3 → ZnAl2O4 Solid-State Reaction: II. Reactivity of Films Deposited onto the Sapphire (001) Face

Mechanisms of Reactions in the Solid State: (110) Al2O3 + (001) ZnO Interfacial Reaction

Matrix-Assisted Energy Conversion in Nanostructured Piezoelectric Arrays

Contact Info

Product

Resources

About

Role of Interfacial Energy and Crystallographic Orientation on the Mechanism of the ZnO + Al₂O₃ → ZnAl₂O₄ Solid-State Reaction: II. Reactivity of Films Deposited onto the Sapphire (001) Face

Role of Interfacial Energy and Crystallographic Orientation on the Mechanism of the ZnO + Al₂O₃ → ZnAl₂O₄ Solid-State Reaction: II. Reactivity of Films Deposited onto the Sapphire (001) Face

Mechanisms of Reactions in the Solid State: (110) Al₂O₃ + (001) ZnO Interfacial Reaction