O2 and CO sensing of Ga2O3 multiple nanowire gas sensors

Liu, Zhifu; Yamazaki, Toshinari; Shen, Yanbai; Kikuta, Toshio; Nakatani, N.; Li, Yongxiang

doi:10.1016/j.snb.2007.09.055

Cited by 187 publications

(98 citation statements)

References 24 publications

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“…In recent years, various nanostructured materials such as nanowires, nanotubes, nanorods and nanobelts, have been evaluated as ideal candidates for gas sensor applications due to their large specific surface areas and dimensions comparable to Debye length [7,8]. In fact, gas sensing materials such as tin oxide [9], titanium oxide [10], zinc oxide [11] and indium oxide [12] with well-established nanostructure have shown higher sensitivity and quicker response in gas detection at low concentrations than their corresponding thin film materials [13,14].…”

Section: Introductionmentioning

confidence: 99%

Solvothermally synthesized tungsten oxide nanowires/nanorods for NO2 gas sensor applications

Qin

Wang

et al. 2011

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 99%

Solvothermally synthesized tungsten oxide nanowires/nanorods for NO2 gas sensor applications

Qin

Wang

et al. 2011

Journal of Alloys and Compounds

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“…The properties of UV detectors [9] and gas sensors [10-12] based on β-Ga 2 O 3 fi lms that were designed to convert solar energy and to detect in the atmosphere reducing and oxidizing gases, including low concentrations of oxygen [12], were reported. Although the optical properties of thin fi lms were investigated earlier [1,2,9,13,14], the dispersion properties and their relationship to the energy structure and crystal properties were not studied in detail. The study of these properties is rather critical.…”

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confidence: 99%

Dispersion of Refractive Index of β-Ga2O3 Thin Films

et al. 2014

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.2 and V. B. LushchanetsThe dispersion of the refractive index of β-Ga 2 O 3 thin fi lms obtained by RF-sputtering was investigated. Anomalous dispersion was observed for fi lms annealed in hydrogen; normal dispersion, for fi lms annealed in oxygen or argon. The spectral dependence in the visible region of the refractive index with normal dispersion was determined mainly by transitions from the top of the valence band formed by oxygen 2p-states to the bottom of the conduction band formed by hybridization of oxygen 2p-states and gallium 4s-states. The single-oscillator approximation parameters, dispersion energy, degree of ionic chemical bonding, and coordination number were found for fi lms with normal dispersion.Keywords: thin fi lm, gallium oxide, refractive index, dispersion.Introduction. Single-and multi-layered fi lms are used to manufacture optical light fi lters and to coat optical components. Recently, thin fi lms of β-Ga 2 O 3 have been widely used. Pure or doped β-Ga 2 O 3 fi lms are used as transparent electrodes for developing gas sensors [1, 2], photoluminophores [3][4][5], and cathodoluminophores or electroluminophores [6-8] depending on the preparation method and dopants. The properties of UV detectors [9] and gas sensors [10-12] based on β-Ga 2 O 3 fi lms that were designed to convert solar energy and to detect in the atmosphere reducing and oxidizing gases, including low concentrations of oxygen [12], were reported. Although the optical properties of thin fi lms were investigated earlier [1,2,9,13,14], the dispersion properties and their relationship to the energy structure and crystal properties were not studied in detail. The study of these properties is rather critical. The refractive index determines the refl ectivity of the fi lms; the dispersion properties, its spectral distribution during fabrication of optical light fi lters or coating of optical components. This prompted the present investigation.Experimental. Ga 2 O 3 thin fi lms (0.2-0.8 μm) were prepared by radiofrequency (RF) ion-plasma sputtering on v-SiO 2 fused quartz substrates. The RF-sputtering used a magnetic fi eld of external solenoids for compression and additional ionization of the plasma column. Deposited fi lms were heat treated in oxygen or Ar at 1000-1100°C and in H 2 at 600-650°C. X-ray powder patterns showed that the fi lms were polycrystalline and differed depending on the heat treatment method. Figure 1 shows characteristic diffraction patterns for the obtained fi lms. The results indicated that the fi lms were oriented in the (400), (002), (111), and (512) planes after annealing in oxygen. Films oriented in the (400), (002), (111), and (512) planes also dominated after annealing in Ar. However, the relative orientation in the (400) plane decreased whereas those in the (111) and (113) planes increased. Films annealed in H 2 showed a weakly developed structure in which refl ections from the (400), (002), and (512) planes also dominated. Refl ections that did not correspond to Ga 2 O 3 were not identifi ed in the dif...

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“…So, the use of NWs instead of thin films as main element of a gas sensor might enhance the sensitivity and selectivity of the final device. The metal oxide studied here is, the monoclinic β-Ga2O3 is a wide band gap material, chemically and thermally stable, well-known for its sensing properties at high temperatures [2][3][4]. This work focuses in the synthesis, physical and optical characterization of β-Ga2O3 NWs followed by the fabrication and characterization of single NW-based gas sensors.…”

Section: Introductionmentioning

confidence: 99%

Individual Gallium Oxide Nanowires for Humidity Sensing at Low Temperature

Domènech-Gil

Riera

López-Aymerich

et al. 2017

Proceedings of Eurosensors 2017, Paris, France, 3–6 September 2017

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Gallium oxide nanowires (NWs) were synthetized using a vapor-liquid-solid route via carbothermal reduction. These NWs were characterized using XRD, SEM and TEM as well as photoluminescence spectroscopy, confirming their crystalline nature. Gas sensors, based on individual NWs, deposited on suspended microhotplates, were tested towards several gases of interest at different temperatures. The sensing towards relative humidity provided the best results, with responses up to 20% at room temperature (~25 °C).

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O2 and CO sensing of Ga2O3 multiple nanowire gas sensors

Cited by 187 publications

References 24 publications

Solvothermally synthesized tungsten oxide nanowires/nanorods for NO2 gas sensor applications

Solvothermally synthesized tungsten oxide nanowires/nanorods for NO2 gas sensor applications

Dispersion of Refractive Index of β-Ga2O3 Thin Films

Individual Gallium Oxide Nanowires for Humidity Sensing at Low Temperature

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