Pt-doped SnO2 thin film based micro gas sensors with high selectivity to toluene and HCHO

Kang, Jun-Gu; Park, Joon‐Shik; Lee, Hoo-Jeong

doi:10.1016/j.snb.2017.03.010

Cited by 98 publications

(29 citation statements)

References 13 publications

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“…Tin oxide is a versatile optical and electrical material that has a broad range of applications in sensing, energy storage, and harvesting applications [12][13][14][15][16][17][18][19] . There are various methods to synthesize SnO 2 nanostructures 13,[20][21][22][23][24] .…”

Section: Resultsmentioning

confidence: 99%

Surface Modification and Charge Injection in a Nanocomposite Of Metal Nanoparticles and Semiconductor Oxide Nanostructures

Xiao

Rutherford

Sharma

et al. 2020

Sci Rep

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Combining two materials in a nanoscale level can create a composite with new functionalities and improvements in their physical and chemical properties. Here we present a high-throughput approach to produce a nanocomposite consisting of metal nanoparticles and semiconductor oxide nanostructures. Volmer-Weber growth, though unfavorable for thin films, promotes nucleation of dense and isolated metal nanoparticles on crystalline oxide nanostructures, resulting in new material properties. We demonstrate such a growth of Au nanoparticles on SnO 2 nanostructures and a remarkable sensitivity of the nanocomposite for detecting traces of analytes in surface enhanced Raman spectroscopy. Au nanoparticles with tunable size enable us to modify surface wettability and convert hydrophilic oxide surfaces into super-hydrophobic with contact angles over 150°. We also find that charge injection through electron beam exposure shows the same effect as photo-induced charge separation, providing an extra Raman enhancement up to an order of magnitude.Metal nanoparticles or nanostructures can interact with the electromagnetic field at optical frequencies. A unique physical property in these nanoparticles is the strong field enhancement associated with localized plasmon excitation, which inspires development of novel devices in applications such as energy harvesting, chemical, and biological sensing. Among them, surface enhanced Raman spectroscopy (SERS) is an analytical technique with high sensitivity that enables the detection of chemical or biological analytes in trace amount far below the limit of the conventional Raman spectroscopy. The enhancement of electromagnetic fields amplifies Raman scattering signals of analytes adsorbed on rough metal surfaces, especially on the rough surfaces generated by noble metal nanostructures. The excitation of localized surface plasmon resonances (LSPRs) in the noble metals is generally considered as the main mechanism of SERS. Theoretical calculations revealed that the electromagnetic enhancement factor can be up to ~10 10 -10 12 1 , reaching the level high enough for single-molecule detection. Therefore, SERS can significantly improve the sensitivity of the conventional Raman spectrometers and provides an accessible and flexible tool to emerging portable and mobile demands in applications such as medical diagnostics, environmental monitoring, food safety, national security, and rapid screening.Noble metal nanoparticles typically exhibit SERS enhancement at sharp edges or gaps between metallic protrusions, called hot spots. Hot spots concentrate electromagnetic radiation energy within small areas, which account for the majority of the Raman scattering signals from SERS. Because the near-field behavior dominates the concentrated electromagnetic radiation in the hot spots, the field strength, as well as associated SERS enhancement, decreases rapidly within the distance of a few nanometers. Hot spots between the nanostructure gaps should be sufficiently small 2-4 . And high-density hot spots are desire...

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Section: Resultsmentioning

confidence: 99%

Surface Modification and Charge Injection in a Nanocomposite Of Metal Nanoparticles and Semiconductor Oxide Nanostructures

Xiao

Rutherford

Sharma

et al. 2020

Sci Rep

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“…Most of the thin films deposited by sputtering, evaporation, CVD, PVD, or ALD techniques require a postannealing process to reorganize and stabilize the original non-crystalline structure [25,29,30]. Thus, the crosslinked networks were post-annealed at high temperature of 500°C in H 2 for 2 h. The change of grain size and surface roughness were hard to distinguish due to the poor conductivity of SnO 2 /NiO for SEM characterization, whereas the SAXS patterns shows more details of the crystallinity in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…First, the traditional MOS thin films by MEMS techniques often show poor sensitivity to target gases due to the compact surface structure and low crystallinity. For example, Kang et al reported a sputtered Pt-doped SnO 2 thin film on microheater with a sensitivity of less than 4 to 25 ppm toluene at 450°C [29]. All the sputtered SnO 2 :NiO thin films in our previous research showed low sensor response of < 2 to 5 ppm NO 2 at 200°C before incorporating the selfassembled Au nanoparticle array [25].…”

Section: Introductionmentioning

confidence: 89%

“…Various traditional MOS thin films can be integrated on the microheaters also by MEMS techniques such as spraying, thermal evaporation, sputtering, physical vapor deposition (PVD), atomic layer deposition (ALD), chemical vapor deposition (CVD), etc. [29][30][31][32]. The collaboration of different MEMS sensors can facilitate the development of array technology to detect gases in complex contexts, which is the prototype of electronic nose (enose) [33][34][35].…”

Section: Introductionmentioning

confidence: 99%

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Sensitive Cross-Linked SnO2:NiO Networks for MEMS Compatible Ethanol Gas Sensors

et al. 2020

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Nowadays, it is still technologically challenging to prepare highly sensitive sensing films using microelectrical mechanical system (MEMS) compatible methods for miniaturized sensors with low power consumption and high yield. Here, sensitive cross-linked SnO 2 :NiO networks were successfully fabricated by sputtering SnO 2 :NiO target onto the etched self-assembled triangle polystyrene (PS) microsphere arrays and then ultrasonically removing the PS microsphere templates in acetone. The optimum line width (~600 nm) and film thickness (~50 nm) of SnO 2 :NiO networks were obtained by varying the plasma etching time and the sputtering time. Then, thermal annealing at 500°C in H 2 was implemented to activate and reorganize the as-deposited amorphous SnO 2 :NiO thin films. Compared with continuous SnO 2 :NiO thin film counterparts, these cross-linked films show the highest response of 9 to 50 ppm ethanol, low detection limits (< 5 ppm) at 300°C, and also high selectivity against NO 2 , SO 2 , NH 3 , C 7 H 8 , and acetone. The gas-sensing enhancement could be mainly attributed to the creating of more active adsorption sites by increased stepped surface in cross-linked SnO 2 :NiO network. Furthermore, this method is MEMS compatible and of generality to effectively fabricate other cross-linked sensing films, showing the promising potency in the production of low energy consumption and wafer-scale MEMS gas sensors.

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“…In the literature, there are several examples of noble metals (Pd, Pt), rare earth metals (Ce, Pr), and metals (Zn, Al) improving the sensitivity and selectivity of various MOXs including SnO 2 [10,[12][13][14][15][16]. Among these materials, magnesium (Mg) is attractive, as it has proved to improve sensitivity to ethanol, H 2 , CO, and ammonia when incorporated into ZnO to form Mg-doped ZnO [17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Influence of Mg Doping Levels on the Sensing Properties of SnO2 Films

Bendahmane

Tomić

Touidjen

et al. 2020

Sensors

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This work presents the effect of magnesium (Mg) doping on the sensing properties of tin dioxide (SnO2) thin films. Mg-doped SnO2 films were prepared via a spray pyrolysis method using three doping concentrations (0.8 at.%, 1.2 at.%, and 1.6 at.%) and the sensing responses were obtained at a comparatively low operating temperature (160 °C) compared to other gas sensitive materials in the literature. The morphological, structural and chemical composition analysis of the doped films show local lattice disorders and a proportional decrease in the average crystallite size as the Mg-doping level increases. These results also indicate an excess of Mg (in the samples prepared with 1.6 at.% of magnesium) which causes the formation of a secondary magnesium oxide phase. The films are tested towards three volatile organic compounds (VOCs), including ethanol, acetone, and toluene. The gas sensing tests show an enhancement of the sensing properties to these vapors as the Mg-doping level rises. This improvement is particularly observed for ethanol and, thus, the gas sensing analysis is focused on this analyte. Results to 80 ppm of ethanol, for instance, show that the response of the 1.6 at.% Mg-doped SnO2 film is four times higher and 90 s faster than that of the 0.8 at.% Mg-doped SnO2 film. This enhancement is attributed to the Mg-incorporation into the SnO2 cell and to the formation of MgO within the film. These two factors maximize the electrical resistance change in the gas adsorption stage, and thus, raise ethanol sensitivity.

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Pt-doped SnO2 thin film based micro gas sensors with high selectivity to toluene and HCHO

Cited by 98 publications

References 13 publications

Surface Modification and Charge Injection in a Nanocomposite Of Metal Nanoparticles and Semiconductor Oxide Nanostructures

Surface Modification and Charge Injection in a Nanocomposite Of Metal Nanoparticles and Semiconductor Oxide Nanostructures

Sensitive Cross-Linked SnO2:NiO Networks for MEMS Compatible Ethanol Gas Sensors

Influence of Mg Doping Levels on the Sensing Properties of SnO2 Films

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