Rapid Fabrication Technique for Interpenetrated ZnO Nanotetrapod Networks for Fast UV Sensors

Gedamu, Dawit; Paulowicz, Ingo; Kaps, Sören; Lupan, Oleg; Wille, Sebastian; Haidarschin, Galina; Mishra, Yogendra Kumar; Adelung, Rainer

doi:10.1002/adma.201304363

Cited by 448 publications

(309 citation statements)

References 72 publications

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“…It is noted that when the NFs are annealed at 400 °C and higher, the XRD spectra exhibit nine distinct peaks at 31 (102), (110), (200), (112), and (201) lattice planes of ZnO (JCPDS, No. 80-0075), accordingly, which confirms the existence of crystalline ZnO NFs.…”

Section: Resultsmentioning

confidence: 99%

“…[26][27][28] As a result, ZnO is usually adopted as the alternative "In-free" active material for metal-oxide-based electronic devices. [29][30][31] In this regard, the electrospun ZnO NFs have the great potential to satisfy all the stringent requirements for practical applications in large-area, low-cost, and high-performance integrated circuits. In any case, the current ZnO NF based TFTs, utilizing either single or multiple NFs as the channel materials, have the comparatively poor performance.…”

Section: Introductionmentioning

confidence: 99%

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ZnO Nanofiber Thin‐Film Transistors with Low‐Operating Voltages

Wang

Song

Zhang

et al. 2017

Adv Elect Materials

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on. [1][2][3][4][5][6][7] Among these 1D nanomaterials, many novel synthesis techniques have then been developed, including chemical vapor deposition (CVD), [8][9][10] hydrothermal methods, [11][12][13] and template-assisted electrodeposition, etc; [14][15][16] however, all of these fabrication schemes come with different process-related disadvantages. For example, CVD has been widely employed for the growth of 1D semiconductor nanostructures, [17,18] in which this technique is still far from being compatible with the large-scale manufacturing platform due to the rather high fabricating cost, rigorous process control, low production throughput, and complicated subsequent device fabrication scheme. [9,19] Although hydrothermal methods are seem to be the simple process and capable to produce large amounts of 1D nanomaterials with the relatively low cost, they are challenging to precisely control the diameter, morphology, and crystal structure of the nanomaterials obtained, seriously influencing their chemical and physical properties, eventually limiting their practical utilizations. [13,20] In general, electrospinning is well accepted to its simplicity and versatility to yield organic, inorganic or composite nanofibers (NFs). [21,22] This technique can not only fabricate NFs with well-controlled properties, such as the excellent crystallinity, homogeneous chemical composition, and uniform diameters but also deliver the high throughput Although significant progress has been made towards using ZnO nanofibers (NFs) in future high-performance and low-cost electronics, they still suffer from insufficient device performance caused by substantial surface roughness (i.e., irregularity) and granular structure of the obtained NFs. Here, a simple onestep electrospinning process (i.e., without hot-press) is presented to obtain controllable ZnO NF networks to achieve high-performance, large-scale, and low-operating-power thin-film transistors. By precisely manipulating annealing temperature during NF fabrication, their crystallinity, grain size distribution, surface morphology, and corresponding device performance can be regulated reliably for enhanced transistor performances. For the optimal annealing temperature of 500 °C, the device exhibits impressive electrical characteristics, including a small positive threshold voltage (V th ) of ≈0.9 V, a low leakage current of ≈10 −12 A, and a superior on/off current ratio of ≈10 6 , corresponding to one of the best-performed ZnO NF devices reported to date. When high-κ AlO x thin films are employed as gate dielectrics, the source/drain voltage (V DS ) can be substantially reduced by 10× to a range of only 0-3 V, along with a 10× improvement in mobility to a respectable value of 0.2 cm 2 V −1 s −1 . These results indicate the potential of these nanofibers for use in next-generation low-power devices. Thin-Film Transistors

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

ZnO Nanofiber Thin‐Film Transistors with Low‐Operating Voltages

Wang

Song

Zhang

et al. 2017

Adv Elect Materials

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“…1 Such metal oxide networks have shown excellent multifunctional and further attractive properties, including fast and sensitive UV detection, as well as significant photocatalytic activity. 1,3 Due to a specific mechanism originating from the interconnected arms in the network, a very fast response with respect to UV photons can be obtained for photosensing applications. 1,3 However, the larger dimensions of the C-FTS tetrapods (arm thickness ~ 1 µm, length ~ 10 µm) leads to a relatively poor gas sensing response for such 3-D network based devices.…”

Section: 3-mentioning

confidence: 99%

“…[2][3] However, the rapid progress in nanotechnologies includes the continuous search of novel materials with new and unique functionalities, which is in focus of many research groups around the world. [1][2][3][4][5][6] In this context, fabrication of three-dimensional (3-D) networks of interconnected ZnO tetrapods (ZnO-T) has been a very important step for progress in engineering, science and nanotechnology. 1,[3][4][6][7][8] Recently the research group of Rainer Adelung has demonstrated a fast and simple synthesis of highly porous interconnected ZnO-T networks by a crucible flame transport synthesis (C-FTS) approach and burner flame transport synthesis (B-FTS).…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3] Nanoarchitectures of semiconducting oxides are becoming important advanced materials with a large variety of exceptional properties for an extensive utilization, ranging from ultraviolet (UV) and gas sensing to biomedical and catalyst applications. [2][3] However, the rapid progress in nanotechnologies includes the continuous search of novel materials with new and unique functionalities, which is in focus of many research groups around the world.…”

Section: Introductionmentioning

confidence: 99%

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Hybridization of Zinc Oxide Tetrapods for Selective Gas Sensing Applications

Lupan

Postica

Gröttrup

et al. 2017

ACS Appl. Mater. Interfaces

136

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In this work, the exceptionally improved sensing capability of highly porous 3-D hybrid ceramic networks with respect to reducing gases is demonstrated for the first time. The 3-D hybrid ceramic networks are based on metal oxides Me= Fe, Cu, Al) doped and alloyed zinc oxide tetrapods (ZnO-T) forming numerous heterojunctions. A change in morphology of the samples and formation of different complex microstructures is achieved by mixing the metallic (Fe, Cu, Al) microparticles with ZnO tetrapods grown by flame transport synthesis (FTS) approach with different weight ratios (ZnO:Me, e.g., 20:1) and followed by subsequent thermal annealing them in air. The gas sensing studies reveal the possibility to control and change/tune the selectivity of the materials, depending on the elemental content ratio and the type of the added metal oxide in 3-D ZnO-T hybrid networks.While pristine ZnO-T networks showed a good response to H2 gas, a change/tune in selectivity to ethanol vapour with a decrease in optimal operating temperature was observed in the networks hybridized with Fe-oxide and Cu-oxide. In case of hybridization with ZnAl2O4 an improvement of H2 gas response (to ≈ 7.5) was reached at lower doping concentrations (20:1), whereas the increasing in concentration of ZnAl2O4 (10:1), the selectivity changes to methane CH4 gas (response ≈ 28). Selectivity tuning to different gases is attributed to the catalytic properties of the metal oxides after hybridization, while the sensitivity improvement is mainly associated with additional modulation of resistance by the built-in potential barriers between n-n and n-p heterojunctions, during adsorption and desorption of gaseous species. Density functional theory based calculations provided the mechanistic insights into the interactions between different hybrid networks and gas molecules supporting the experimentally observed results. The studied materials and sensor structures would provide particular advantages in the field of fundamental research, industrial and ecological applications.

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