WO3 and WTiO thin-film gas sensors prepared by sol–gel dip-coating

Shieh, Jiann; Feng, H. M.; Hon, Min–Hsiung; Juang, Horng-Yih

doi:10.1016/s0925-4005(02)00150-8

Cited by 97 publications

(39 citation statements)

References 22 publications

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“…national requirement standard 41 , and is comparable to sensors fabricated from as-grown nanotubes conventional Si substrates. Furthermore, these flexible sensors are 100-fold more sensitive than thin-film metal-oxide sensors 42,43 . We attribute this exquisite sensitivity to the fact that binding events occur near the top surface of the NWs, where most of the charge carriers reside.…”

Section: Flexible Nanowire Vapour Sensorsmentioning

confidence: 99%

Highly ordered nanowire arrays on plastic substrates for ultrasensitive flexible chemical sensors

et al. 2007

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The development of a robust method for integrating high-performance semiconductors on flexible plastics could enable exciting avenues in fundamental research and novel applications. One area of vital relevance is chemical and biological sensing, which if implemented on biocompatible substrates, could yield breakthroughs in implantable or wearable monitoring systems. Semiconducting nanowires (and nanotubes) are particularly sensitive chemical sensors because of their high surface-to-volume ratios. Here, we present a scalable and parallel process for transferring hundreds of pre-aligned silicon nanowires onto plastic to yield highly ordered films for low-power sensor chips. The nanowires are excellent field-effect transistors, and, as sensors, exhibit parts-per-billion sensitivity to NO 2 , a hazardous pollutant. We also use SiO 2 surface chemistries to construct a 'nano-electronic nose' library, which can distinguish acetone and hexane vapours via distributed responses. The excellent sensing performance coupled with bendable plastic could open up opportunities in portable, wearable or even implantable sensors.The fabrication of electronic devices on plastic substrates has attracted considerable recent attention owing to the proliferation of handheld, portable consumer electronics. Plastic substrates possess many attractive properties including biocompatibility, flexibility, light weight, shock resistance, softness and transparency [1][2][3] . However, most plastics deform or melt at temperatures of only 100−200 °C, placing severe limitations on the quality of semiconductors that can be grown directly on plastic. Central to continued advances in highperformance plastic electronics is the development of robust methods for overcoming this temperature restriction. Recently, three categories of approaches have emerged to address this problem.The first approaches are crystallization methods, in which an inferior inorganic semiconductor is vapour deposited at low temperatures onto plastic, and subsequently crystallized. An example is the conversion of amorphous silicon into polycrystalline silicon via laser crystallization 4 . Polysilicon thin-film transistors (TFTs) made in this way have yielded electron mobilities up to 250 cm 2 V −1 s −1 and hole mobilities up to 65 cm 2 V −1 s −1 (refs 5-7). However, this approach suffers from an inherent dichotomy between achieving high performance, which requires larger crystal grain sizes, and achieving homogeneity, which requires smaller grain sizes for uniformity in number of grain boundaries per © 2007 Nature Publishing Group * Correspondence and requests for materials should be addressed to J.R.H. heath@caltech.edu. Author contributions Competing financial interestsThe authors declare no competing financial interests. NIH Public Access TRANSFER OF NANOWIRES ONTO PLASTICThe dry transfer process uses the fact that the SNAP procedure is carried out on silicon-onoxide (SOI) wafers, as the buried silica can be readily etched to free the wires for transfer. Figure 1 summa...

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Section: Flexible Nanowire Vapour Sensorsmentioning

confidence: 99%

Highly ordered nanowire arrays on plastic substrates for ultrasensitive flexible chemical sensors

et al. 2007

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“…Tungsten oxide thin films have been the object of research in numerous recent publications due to their promising properties in gas sensing [1], photocatalysis [2,3] and electrochromic devices [4][5][6]. In the latter case, because of their superior coloration efficiency, chemical stability, electronic and ionic conductivity [7], tungsten oxide thin films expanded the horizons from the experimental level to the commercialization in the area of smart windows'' [6].…”

Section: Introductionmentioning

confidence: 99%

Mesoporous amorphous tungsten oxide electrochromic films: a Raman analysis of their good switching behavior

Chatzikyriakou

Gilbert

Colson

et al. 2014

Electrochimica Acta

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A c c e p t e d M a n u s c r i p tThe intercalation and de-intercalation of lithium cations in electrochromic tungsten oxide thin films are significantly influenced by their structural and surface characteristics.In this study, we prepared two types of amorphous films via the sol-gel technique: one dense and one mesoporous in order to compare their response upon lithium intercalation and deintercalation.According to chronoamperometric measurements, Li + intercalates/de-intercalates faster in the mesoporous film (24s/6s) than in the dense film (48s/10s bronze.

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“…[1][2][3][4] For the applications that rely on surface area such as photocatalyst and gas sensor, very fine powders with low particle agglomeration are favorable since they possess high specific surface area for gas adsorption and/or desorption. Due to simplicity of equipment employed, the WO 3 powders are typically prepared by wet chemical processes such as sol-gel 5) and precipitation. 4,6) Thermal decomposition and pyrolysis of tungsten salt are also common for preparation of the powder for gas sensor application.…”

Section: Introductionmentioning

confidence: 99%

Effect of SiO2 Doping on Growth Retardation of WO3 Nanoplate

Supothina

2007

JMMP

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Tungsten oxide (WO 3 ) is recently recognized as one of the most widely studied gas sensitive ceramics. To maintain good thermal stability at moderate operating temperature, the gas sensitive materials were typically heated at several hundreds degree Celsius. Such treatment caused grain growth, resulting to reduction of specific surface area which is considered to be one of the important properties determining gas sensor's performance. In this present work, grain growth of the WO 3 nanoplate was retarded by incorporation of silica (SiO 2 ) particle. To obtain homogeneous structure, the SiO 2 was incorporated by mixing tetraethyl orthosilicate into the W precursor during precipitation of the tungsten oxide. It was found that the SiO 2 dramatically retarded the particle growth, preserved the nanoplate structure, and resulted to more porous WO 3 powder. The effect was very significant when the powders were calcined at high temperatures.

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WO3 and WTiO thin-film gas sensors prepared by sol–gel dip-coating

Cited by 97 publications

References 22 publications

Highly ordered nanowire arrays on plastic substrates for ultrasensitive flexible chemical sensors

Highly ordered nanowire arrays on plastic substrates for ultrasensitive flexible chemical sensors

Mesoporous amorphous tungsten oxide electrochromic films: a Raman analysis of their good switching behavior

Effect of SiO2 Doping on Growth Retardation of WO3 Nanoplate

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