Selective hydrogen gas nanosensor using individual ZnO nanowire with fast response at room temperature

Lupan, Oleg; Ursaki, V. V.; Chai, Guangyu; Chow, Lee; Емельченко, Г. А.; Tiginyanu, I. M.; Грузинцев, А. Н.; Редькин, А. Н.

doi:10.1016/j.snb.2009.10.038

Cited by 422 publications

(264 citation statements)

References 95 publications

(153 reference statements)

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“…Similar observations were found for single nanowire sensors with diameter 40 nm, close to the depletion zone depth (13.4 nm) calculated for NO 2 adsorbed on SnO 2 , which had higher response to NO 2 compared to wires with larger diameters (between 62 and 117 nm) [57]. This is similar to the results found previously for ZnO nanowires [38], although the rationale provided is different (increased defect density for ZnO and Debye length for SnO 2 ). Thinner nanowires also showed an improved detection limit to NO 2 ( Figure 7).…”

Section: Tin Oxidesupporting

confidence: 89%

“…Similarly improved sensor response to H 2 was recorded for single ZnO wires 100 nm in diameter as opposed to wires with diameters of 200 nm or 600 nm which showed lower responses (less than 10%) [38]. These results were attributed to the higher concentration of structural defects when the diameter of ZnO wires are decreased, and hence by targeting wires with smaller diameters sensor performance can be optimized.…”

Section: Zinc Oxidementioning

confidence: 66%

“…Metallic Zn [36][37][38][39][40][41][42][43] or diethylzinc (Et 2 Zn) [44][45][46][47], both with O 2 as carrier (reactive) gas, have been used as precursors for the formation of ZnO via CVD, although other simple precursors such as zinc nitrate (Zn(NO 3 ) 2 ) [48] and organometallic complexes (e.g., Zn(II) ketoiminate) [49,50], have also been reported. ZnO films or NPs have been typically achieved at deposition temperatures between 350 and 450˝C, whereas NS of this material have been reported at deposition temperatures exceeding 450˝C, either with or without the use of gold (catalytic) seeds to encourage NS formation.…”

Section: Zinc Oxidementioning

confidence: 99%

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Chemical Vapour Deposition of Gas Sensitive Metal Oxides

et al. 2016

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This article presents a review of recent research efforts and developments for the fabrication of metal-oxide gas sensors using chemical vapour deposition (CVD), presenting its potential advantages as a materials synthesis technique for gas sensors along with a discussion of their sensing performance. Thin films typically have poorer gas sensing performance compared to traditional screen printed equivalents, attributed to reduced porosity, but the ability to integrate materials directly with the sensor platform provides important process benefits compared to competing synthetic techniques. We conclude that these advantages are likely to drive increased interest in the use of CVD for gas sensor materials over the next decade, whilst the ability to manipulate deposition conditions to alter microstructure can help mitigate the potentially reduced performance in thin films, hence the current prospects for use of CVD in this field look excellent.

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Section: Tin Oxidesupporting

confidence: 89%

Section: Zinc Oxidementioning

confidence: 66%

Section: Zinc Oxidementioning

confidence: 99%

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Chemical Vapour Deposition of Gas Sensitive Metal Oxides

et al. 2016

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“…26 Thus, micro-Raman measurements can provide useful information about material quality. Figure 3 depicts the RT micro-Raman spectra of the studied samples.…”

Section: Znxme1-xoy 3-d Hybrid Networkmentioning

confidence: 99%

Hybridization of Zinc Oxide Tetrapods for Selective Gas Sensing Applications

Lupan

Postica

Gröttrup

et al. 2017

ACS Appl. Mater. Interfaces

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136

113

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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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“…In our model, since conduction electrons accumulate at the surface V + o state, response time is correlated with V + o due to surface band bending. Therefore, more band bending implies more V + o states and promotes the V + o → V o transition, which can explain why better response was observed for gas sensors with reduced NR diameter 25 . Furthermore, our model implies O 2 desorption is only one route to obtain charge separation through the V + o state.…”

mentioning

confidence: 99%

Photoluminescence transient study of surface defects in ZnO nanorods grown by chemical bath deposition

Barbagiovanni

Strano

Franzò

et al. 2015

Applied Physics Letters

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Two deep level defects (2.25 and 2.03 eV) associated with oxygen vacancies (V o ) were identified in ZnO nanorods (NRs) grown by low cost chemical bath deposition. A transient behaviour in the photoluminescence (PL) intensity of the two V o states was found to be sensitive to the ambient environment and to NR postgrowth treatment. The largest transient was found in samples dried on a hot plate with a PL intensity decay time, in air only, of 23 and 80 s for the 2.25 and 2.03 eV peaks, respectively. Resistance measurements under UV exposure exhibited a transient behaviour in full agreement with the PL transient indicating a clear role of atmospheric O 2 on the surface defect states. A model for surface defect transient behaviour due to band bending with respect to the Fermi level is proposed. The results have implications for a variety of sensing and photovoltaic applications of ZnO NRs.PACS numbers: 68.43. Fg, 68.43.Tj, 73.20.Hb, 73.20.At Zinc oxide is a wide band gap (∼ 3.2→3.4 eV) ntype semiconductor with a large exciton binding energy (60 meV) and is a promising material for a range of applications 1 . However, studies on low cost ZnO nanostructures (NSs) and thin films are unclear as to the source of n-type conductivity and persistent photoconductivity (PPC), the UV sensing mechanism, and the defect landscape 2,3 . In particular, the correlation between the defect landscape and sensing (whether gas, pH, or UV) responsivity in low cost ZnO NRs is debated. In one model, the neutral oxygen vacancy (V o ) is an n-type donor state 3 , atmospheric O 2 absorbs at this site 2 , and a depletion region forms beneath the surface 4 . UV excitation creates electron-hole pairs, holes migrate to the depletion region and O 2 desorption occurs, thus reducing the depletion region and increasing the conductivity 4,5 . Therefore, the kinetics of O 2 desorption determine the response time of a UV sensor. In a second model, V o is reported to be a deep level state (DLS) The quality, diameter, and length of the NRs was measured using a Gemini field emission scanning electron microscopy (SEM) Carl Zeiss SUPRATM 25. CBD introduces water based absorbates 13-15 , we controlled this parameter by comparing samples as-prepared not dried (ND), dried at 100 o C for 20 min on a hot plate, and left to dry over two weeks. Additionally, we annealed a sample at 600 o C for 30 min in O 2 to understand the role of V o .Resistance measurements were performed under exposure to 364 nm UV light. The samples were biased to force a current of 1 nA between two probes 1 mm apart to extract the resistance. This value was used to avoid compliance in the samples and gave a good overall response under UV exposure. PL measurements were performed by pumping at 1.5 mW the 325 nm line of a He-Cd laser chopped through an acousto-optic modulator at a frequency of 55 Hz. The PL signal was analyzed by a single grating monochromator, detected with a Hamamatsu visible photomultiplier, and recorded with a lock-in am-

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Selective hydrogen gas nanosensor using individual ZnO nanowire with fast response at room temperature

Cited by 422 publications

References 95 publications

Chemical Vapour Deposition of Gas Sensitive Metal Oxides

Chemical Vapour Deposition of Gas Sensitive Metal Oxides

Hybridization of Zinc Oxide Tetrapods for Selective Gas Sensing Applications

Photoluminescence transient study of surface defects in ZnO nanorods grown by chemical bath deposition

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