Nucleation mechanism of the seed of tetrapod ZnO nanostructures

Ronning, Carsten; Shang, N. G.; Gerhards, I.; Hofsäß, H.; Seibt, M.

doi:10.1063/1.1997290

Cited by 88 publications

(88 citation statements)

References 31 publications

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“…On the contrary, high laser powers (high temperatures) lead to a predominant formation of tetrapods. These results are in agreement with the growth mechanism reported by Ronning et al 39 . It is important to note that the rods on the tip of the precursor are only formed for high laser powers.…”

Section: Znosupporting

confidence: 83%

ZnO micro/nanocrystals grown by laser assisted flow deposition

et al. 2014

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Laser assisted flow deposition (LAFD) is a very high yield method based on a vapor-solid mechanism, allowing the production of ZnO crystals in a very short time. The LAFD was used in the growth of different morphologies (nanoparticles, tetrapods and microrods) of ZnO micro/nanocrystals and their microstructural characterization confirms the excellent crystallinity of the wurtzite structure. The optical properties of the as-grown ZnO crystals investigated by low temperature photoluminescence (PL) evidence a well-structured near band edge emission (NBE) due to the recombination of free (FX), surface (SX) and donor bound (D 0 X) excitons. Among the most representative emission lines, the 3.31 eV transition was found to occur in the stacking faults-free microrods. The luminescence behavior observed in H passivated samples suggests a closer relationship between this optical center and the presence of surface states.Besides the unintentionally doped micro/nanocrystals, ZnO/Ag and ZnO/carbon nanotubes (CNT) hybrid structures were processed by LAFD. The former aims at the incorporation of silver as a p-type dopant and the latter envisaging photovoltaic applications. Silver-related spherical particles were found to be inhomogeneously distributed at the microrods surface, accumulating at the rods tips and promoting the ZnO nanorods re-nucleation. Despite the fact that energy dispersive X-ray measurements suggest that a fraction of the silver could be incorporated in the ZnO rods, no new related luminescence lines or bands were observed when compared with the as-grown samples. For the case of the ZnO/CNT composites two main approaches were adopted: i) a direct deposition of ZnO particles on the surface of vertically aligned multi-walled carbon nanotubes (VACNTs) forests without employing any additional catalyst and ii) new ZnO/CNT hybrids were developed as buckypaper nanocomposites. The use of the LAFD technique in the first approach preserves the CNTs structure and alignment and avoids the collapse of the VACNTs array, which is a major advantage of this method. On the other hand, LAFD grown ZnO nanoparticles and tetrapods were used to produce ZnO/CNT buckypaper nanocomposites. When compared with the as-grown samples the PL spectra of the composites structures behave differently. For the case of the ZnO/VACNTs no changes on the peak position and spectral shape were observed. Only an enhancement of the overall luminescence was found to occur. On contrary, for the buckypaper nanocomposites notable changes on the spectral shape and peak position were observed, likely due to distinct surface band bending effects for the ZnO nanoparticles and tetrapods embedded in the CNTs.

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Section: Znosupporting

confidence: 83%

ZnO micro/nanocrystals grown by laser assisted flow deposition

et al. 2014

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“…[2] In this work, we report the synthesis of tetrapodlike ZnSSe alloy nanostructures (T-ZnSSe) of different compositions by catalyst-free chemical vapor deposition (CVD) and the studies of their composition-dependent Raman scattering and cathodoluminescence (CL). Novel tetrapod-like structures, constructed from 1D nanorods, have been observed in almost all the binary II-VI compounds, [3][4][5][6][7][8][9][10][11][12] but have not been in their ternary alloys. It has also been demonstrated that these tetrapod nanocrystals have many potential applications in waveguides, [13] photodiodes, [14] transistors, [15] field emission devices, [16] gas sensors, [17] and biomolecule delivery.…”

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confidence: 99%

Synthesis and Optical Properties of Tetrapod‐Like ZnSSe Alloy Nanostructures

Liang

Liu

et al. 2008

Advanced Materials

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“…The arms are usually single crystal wurtzite with lattice parameters a = 0.25 nm and c = 0.52 nm. The structure of the nucleus is of some debate because for different tetrapod sizes and morphologies different conclusions about its core structure have been made [2].…”

Section: Introductionmentioning

confidence: 99%

Aberration corrected and 3D cryo-tomography HAADF-STEM surface studies of ZnO tetrapods

Ward

Sugiura

Yoshida

et al. 2012

J. Phys.: Conf. Ser.

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Abstract. We present a morphology study of ZnO tetrapods using aberration corrected TEM, HAADF-STEM and 3D HAADF-STEM cryotomography as an alternative to more conventional TEM and SEM techniques. We use 3D IMOD reconstructions to show that the {1 1 0} facets dominate the total surface area of uniform hexagonal prism tetrapods. Using HRTEM we show that the small tetrapods have a zincblende phase core from which the four legs extend. The facets and the edges of these legs were found to be atomically clean and flat with the potential for ZnO tetrapods as model substrates. We deposited ultrafine Pt/Pd nanoparticles onto the tetrapods and investigated the resulting morphologies. We found using HAADF-STEM cryotomography and reconstruction techniques that the nanoparticle coverage gave separate nanoparticles and overall uniform coverage. We believe these techniques and the results from them could be useful for the development of nanoparticle-ZnO tetrapod composite systems with applications in optoelectronics, gas sensing and catalysis.

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Nucleation mechanism of the seed of tetrapod ZnO nanostructures

Cited by 88 publications

References 31 publications

ZnO micro/nanocrystals grown by laser assisted flow deposition

ZnO micro/nanocrystals grown by laser assisted flow deposition

Synthesis and Optical Properties of Tetrapod‐Like ZnSSe Alloy Nanostructures

Aberration corrected and 3D cryo-tomography HAADF-STEM surface studies of ZnO tetrapods

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