Formation of one-dimensional ZnO nanowires from screw-dislocation-driven two-dimensional hexagonal stacking on diamond substrate using nanoparticle-assisted pulsed laser deposition
TL;DR: In this article, the growth of 1D ZnO nanowires on a p-type diamond substrate using nanoparticle-assisted pulsed laser deposition technique was reported, and the growth velocities at different regions of the hexagons were analyzed.
Abstract: We report on the growth of ZnO nanowires on a p-type diamond substrate using nanoparticle-assisted pulsed laser deposition technique. Microstructural analysis on different growth stages reveals that the self-assembled 1D ZnO nanowires emerge on well-formed 2D hexagonal base with spiral-like structures. We explain the formation of screw-dislocation-driven spiral-like-hexagons invoking crystal growth velocities at different regions of the hexagons. High-resolution transmission electron microscopy and selective area electron diffraction studies show that the nanowires are single crystalline in nature and grow along 〈0 0 0 1〉 direction of the wurtzite hexagonal structure. Room temperature photoluminescence spectrum of the ZnO nanowire shows a strong near band edge emission at 3.2 eV with a linewidth of 136 meV.
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TL;DR: A screw dislocated Eshelby twist origin in cationic assimilated ZnO nanowires synthesized via Successive Ionic Layer Absorption and Reaction (SILAR) technique was proposed in this article.
Abstract: Insight into the controlled growth features of nanowires has been in the prominent spotlight for engineering the material properties Defect and dislocation induced nanowire growth has been emerging as a robust model by dwindling the conventional growth models In this context, we have proposed a screw dislocated Eshelby twist origin in cationic assimilated ZnO nanowires synthesized via Successive Ionic Layer Absorption and Reaction (SILAR) technique The growth of twisted nanowires occurred through a subsequent transformation from nanoflakes to nanoflowers Presence of twist contours in various zone axis pattern provided strong validation of Eshelby origin in twisted nanowires The preferential plane orientation of (0 0 0 2) confirmed the twisted growth along c-axis orientation Presence of screw tail at the twisted end of nanowire confirmed the influence of Peach-Kohler force acted on the screw axis Active vibrational modes and surface defect states of nanoflowers and nanowires were investigated and reported Twisted ZnO nanowires showed maximum sensing response of 291 towards 100 ppm of ammonia at room temperature with the lowest detection limit of 5 ppm The response and recovery times were found to be 39 and 17 s Influence of grain alignment, grain orientation and potential barrier height on ammonia sensing signatures are reported
48 citations
TL;DR: In this article, a review of the recent advances on the materials, fabrication, and application of pulsed-laser deposition for a variety of high-performance photo-detectors from an overall perspective is presented.
Abstract: In the past decade, photo-detectors have been demonstrated to have very important applications in image sensing, optical communication, fire detection, environmental monitoring, space exploration, safety detection, and many other scientific research and industrial technology fields and are regarded as the key components of wearable devices. Compared to traditional fabrication approaches, pulsed-laser deposition (PLD)-grown materials for photo-detectors offer several merits. First, PLD is a clean physical vapor deposition approach. A stoichiometric amount of atoms can be transferred from the target to the substrate, avoiding complicated and potentially dangerous chemical reactions. Furthermore, the PLD process is carried out in a high-vacuum environment. Therefore, almost no contaminants, such as catalysts, precursors, surfactants and by-products, will be introduced. Also, the thickness of the films can be controlled by simply manipulating the energy and pulse number of the pulsed laser. Furthermore, the fabrication temperature is relatively low, which is available to deposit materials on various substrates, even flexible ones. Most importantly, PLD is a deposition technology with large area coverage, which can produce centimeter-scale thin films, the planar geometry of which has significant potential for compact device integration with modern semiconductor techniques. Consequently, this review introduces the recent advances on the materials, fabrication, and application of pulsed-laser deposition for a variety of high-performance photo-detectors from an overall perspective. Moreover, the challenges and future development trends are discussed.
19 citations
TL;DR: Results indicate PLD combined with a sacrifical nanostructure is a promising method for obtaining high-quality ZnO nanorod microstructure, which paves the way for the fabrication of high performance ZnNO-based devices.
Abstract: A novel fabrication method for single crystalline ZnO nanorods by pulsed laser deposition (PLD) using a chemical-bath-deposited ZnS seed layer is proposed. For the substrate temperature (Ts) lower than 700 °C, the PLD-ZnO showed a polycrystalline phase and film-type morphology, resulting from the ZnS seed layer with a cubic phase. However, the ZnS film became a sacrifical layer and single crystalline ZnO(002) nanorods can be achieved at Ts of 900 °C, where ZnS was decomposed to zinc metals and sulfur fumes. The transformation from ZnO film to nanorod microstructure was demonstrated with the change of ZnS layer into Zn grains. Enhanced performance of the metal-semiconductor-metal photodetectors were fabricated with ZnO/ZnS samples grown at Ts of 500, 700, and 900 °C. The responsivities (@1 V and 370 nm) of these three devices were 1.71, 6.35, and 98.67 A/W, while their UV-to-visible discrimination ratios were 7.2, 16.5, and 439.1, respectively. Obviously, a higher light-capturing efficiency was obtained in the 900 °C-grown ZnO/ZnS device owing to its one-dimensional nanostructure with high crystal quality. The results indicate PLD combined with a sacrifical nanostructure is a promising method for obtaining high-quality ZnO nanorods, which paves the way for the fabrication of high performance ZnO-based devices.
16 citations
TL;DR: In this article, the growth of ZnO nanostructures in different gas ambient (Ar and N 2 ) using pulsed laser deposition technique was reported, and the nanorods are c-axis oriented and highly epitaxial in nature.
15 citations
TL;DR: Triclinic (t-) Ba2V2O7 helical-like meso/nanosquares assembled from self-spiraling nanosheets have been controllably synthesized by a high-efficiency microwave irradiation-assisted surfactant process.
Abstract: Triclinic (t-) Ba2V2O7 helical-like meso/nanosquares assembled from self-spiraling nanosheets have been controllably synthesized by a high-efficiency microwave irradiation-assisted surfactant process. The microstructure and morphology of the as-prepared t-Ba2V2O7 products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results show that the spirals of stacked nanosheets grow along the z-axis of microsquares, leading to the formation of a helical shape. Based on parallel experiments and theoretical analysis of t-Ba2V2O7 helical mesosquares at different reaction stages, the formation mechanism has been proposed to be a “self-assembly–dissolution–recrystallization–Ostwald-ripening” mechanism. The helical structures with uniform morphology and size may find promising applications in a variety of fields. The SDBS-assisted microwave irradiation method offers an easy path to the controllable fabrication of helical Ba2V2O7meso/nanomaterials, which can be readily extended to the development of functional structures of other alkaline earth vanadates. Moreover, it is found that the helical-like materials exhibit unique magnetic properties, corresponding to shape evolutions with different particle sizes at continuous reaction time.
15 citations
References
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TL;DR: This work has shown that integration of nanowires is especially promising for the preparation of short-wavelength emitters such as superluminescent UV-light-emitting diodes and laser diods and an alternative promising approach is to grow n-type ZnO NWs on p-type GaN.
Abstract: Nanowire (NW)-based light-emitting diodes (LEDs) have drawn great interest because of their many advantages compared to thin-fi lm-based devices. Marked improved performances are expected from nanostructured active layers for light emission. Nanowires can act as direct waveguides and favor light extraction without use of lenses and refl ectors. Moreover, the use of wires avoids the presence of grain boundaries and then the emission effi ciency is boosted by the absence of nonradiative recombinations at the joint defects. The junctions between the nand p-type semiconductors can also be of very high quality with low interfacial strain and defect density as a result of a reduced contact area between the two materials in the case of epitaxial heterojunctions. Integration of nanowires is especially promising for the preparation of short-wavelength emitters such as superluminescent UV-light-emitting diodes and laser diodes. GaN is the main wide-bandgap semiconductor ( E g = 3.39 eV) used for the preparation of blue and UV LEDs. However GaN nanowire arrays are diffi cult to grow. [ 1 , 2 ] Alternative materials for the preparation of nanostructured UV LEDs mainly include ZnO. [ 3–5 ] ZnO has a similar wide bandgap of 3.37 eV and a larger exciton binding energy of 60 meV (compared to 29 meV in the case of GaN) that should favor light emission at room temperature. [ 3 , 6 ] ZnO and GaN share the same wurtzite hexagonal structure. A lot of research efforts have focused on the preparation of p-type ZnO to realize LEDs based on homojunctions made of this semiconductor. [ 7–9 ] For the moment, however, reproducible and stable p-type ZnO material with suffi cient high conductivity and carrier concentration is still at the development phase. An alternative promising approach is to grow n-type ZnO NWs on p-type GaN. [ 10–17 ] ZnO NWs can be grown by various techniques. Most of these efforts for LED applications have been focused on vapor phase growth. Recently, devices have
288 citations
TL;DR: It is shown that nanotube growth can be driven by axial screw dislocations: self-perpetuating growth spirals enable anisotropic growth, and the dislocation strain energy overcomes the surface energy required for creating a new inner surface forming hollow tubes spontaneously.
Abstract: Single-crystal nanotubes are commonly observed, but their formation is often not understood. We show that nanotube growth can be driven by axial screw dislocations: Self-perpetuating growth spirals enable anisotropic growth, and the dislocation strain energy overcomes the surface energy required for creating a new inner surface forming hollow tubes spontaneously. This was demonstrated through solution-grown zinc oxide nanotubes and nanowires by controlling supersaturation using a flow reactor and confirmed using microstructural characterization. The agreement between experimental growth kinetics and those predicted from fundamental crystal growth theories confirms that the growth of these nanotubes is driven by dislocations.
272 citations
TL;DR: In this article, columnar-structured diamond films with column diameters less than 100 nm and thickness in the range of 1-5 μm were grown on silicon substrates by chemical vapor deposition (CVD) in a microwave plasma reactor with purified methane and hydrogen used as the reactants.
Abstract: Nanocrystalline columnar-structured diamond films with column diameters less than 100 nm and thicknesses in the range of 1–5 μm were grown on silicon substrates by chemical vapor deposition (CVD) in a microwave plasma reactor with purified methane and hydrogen used as the reactants. Uniform conformal nucleation densities in excess of 1012 cm−2 were accomplished prior to growth by seeding with explosively formed nanodiamonds, which resulted in good optical quality films. The film thickness was measured in situ by the laser reflectometry method. The grain size and optical quality of the films were characterized by scanning electron microscopy and Raman measurements. Broadband surface acoustic wave pulses were used to measure the anomalous dispersion in the layered systems. The experimental dispersion curves were fitted by theory, assuming the diamond film as an isotropic layer on an anisotropic silicon substrate, to determine mean values of the density and Young’s modulus of the diamond films. The density w...
266 citations
TL;DR: In this paper, high-pressure pulsed-laser deposition (PLD) was used to grow MgxZn1−xO nanowires on gold-covered sapphire single crystals.
Abstract: MgxZn1−xO nanowires with Mg-content x from 0 to 0.2 have been grown by high-pressure pulsed-laser deposition (PLD) on gold-covered sapphire single crystals. The PLD process allows for a unique wide-range control of morphology, diameter, and composition of the MgxZn1−xO nanowires. The diameter of single ZnO wires could be varied between about 50 and 3000 nm, and the Mg content x of MgxZn1−xO wire arrays was controlled via the PLD gas pressure. The microscopic homogeneity of Mg content is displayed by cathodoluminescence (CL) imaging of the excitonic peak energy. The fluctuation of CL peak energy between individual wires is about an order of magnitude smaller than the alloy broadening.
191 citations
TL;DR: A unified scheme general to any crystalline material that explains the growth of nanoplates as well as different dislocation-driven nanomaterial morphologies are proposed through consideration of the relative crystal growth step velocities at the dislocation core versus the outer edges of the growth spiral under various supersaturations.
Abstract: We report the dislocation-driven growth of two-dimensional (2D) nanoplates They are another type of dislocation-driven nanostructure and could find application in energy storage, catalysis, and nanoelectronics We first focus on nanoplates of zinc hydroxy sulfate (3Zn(OH)2·ZnSO4·05H2O) synthesized from aqueous solutions Both powder X-ray and electron diffraction confirm the zinc hydroxy sulfate (ZHS) crystal structure as well as their conversion to zinc oxide (ZnO) Scanning electron, atomic force, and transmission electron microscopy reveal the presence of screw dislocations in the ZHS nanoplates We further demonstrate the generality of this mechanism through the growth of 2D nanoplates of α-Co(OH)2, Ni(OH)2, and gold that can also follow the dislocation-driven growth mechanism Finally, we propose a unified scheme general to any crystalline material that explains the growth of nanoplates as well as different dislocation-driven nanomaterial morphologies previously observed through consideration of th
166 citations