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Journal ArticleDOI

Near Room Temperature Sensing by In₂O₃ Decorated Silicon Nanowires for Sensitive Detection of Ethanol

15 Mar 2021-IEEE Sensors Journal (Institute of Electrical and Electronics Engineers (IEEE))-Vol. 21, Iss: 6, pp 7275-7282
Abstract: The role of indium trioxide (In2O3) decorated Si nanowires (SiNWs) based resistive sensor for selective detection of ethanol vapors at near room temperature has been successfully demonstrated. SiNWs samples were synthesized using metal assisted chemical etching technique and these were decorated by a thin film of indium followed by annealing. The sensing response was captured by measuring the change in resistance of the sensing layer using a Cr-Au inter-digitated-electrode (IDE) structure formed on top of the sensing layers. All sensors were tested for ethanol, acetone, iso-propanol (IPA), xylene, benzene and toluene vapours in the wide concentration range of 5–500 ppm and at different temperatures. Sensors based on SiNWs alone had displayed higher response towards acetone vapours whereas after heterojunction formation with In2O3, significant sensitivity to ethanol was depicted. In2O3 decorated SiNWs resulted in significant enhancement of the sensor response% towards ethanol at near room temperature. Minimum detection of ethanol at 50 ppm and 10 ppm was portrayed by SiNWs and In2O3/SiNWs based sensors respectively. It was concluded that sensing behaviour was a consequence of combinatory effect produced by the presence of both SiNWs and In2O3. A simple explanation with device schematic and band diagrams of the material are proposed to describe the sensing mechanism. This study demonstrates the significance of surface treatment of SiNWs and the role of heterostructures for tuning the sensing properties and development of wafer scalable sensors. more

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Journal ArticleDOI
Xiao Liu1, Sitian Cheng, Hong Liu1, Sha Hu  +2 moreInstitutions (2)
16 Jul 2012-Sensors
TL;DR: This paper focuses on sensitivity and selectivity for performance indicators to compare different sensing technologies, analyzes the factors that influence these two indicators, and lists several corresponding improved approaches. more

Abstract: Sensing technology has been widely investigated and utilized for gas detection. Due to the different applicability and inherent limitations of different gas sensing technologies, researchers have been working on different scenarios with enhanced gas sensor calibration. This paper reviews the descriptions, evaluation, comparison and recent developments in existing gas sensing technologies. A classification of sensing technologies is given, based on the variation of electrical and other properties. Detailed introduction to sensing methods based on electrical variation is discussed through further classification according to sensing materials, including metal oxide semiconductors, polymers, carbon nanotubes, and moisture absorbing materials. Methods based on other kinds of variations such as optical, calorimetric, acoustic and gas-chromatographic, are presented in a general way. Several suggestions related to future development are also discussed. Furthermore, this paper focuses on sensitivity and selectivity for performance indicators to compare different sensing technologies, analyzes the factors that influence these two indicators, and lists several corresponding improved approaches. more

883 citations

Journal ArticleDOI
Abstract: This review deals with gas sensors combining a metal oxide based sensing layer and a substrate realized by using micromachining. It starts by giving an overview of the design principles and technology involved in the fabrication of micromachined substrates examining thermal and mechanical aspects. Both kinds of micromachined substrates, closed-membrane-type and the suspended-membrane-type, are discussed. The deposition of the sensing layer is complicated by the mechanical fragility of the micromachined substrates. Different approaches used for the formation of the sensing layer such as thin film and thick film deposition techniques are reviewed. Finally, the gas sensing function of the sensitive layer is analyzed and various ways for extracting the information are presented with respect to the improvement of sensor performance brought by this new approach. more

593 citations

Journal ArticleDOI
TL;DR: The role of graphene in fabricating flexible gas sensors for the detection of various hazardous gases, including nitrogen dioxide, ammonia, hydrogen, hydrogen sulfide, carbon dioxide, sulfur dioxide, and humidity in wearable technology, is discussed. more

Abstract: Wearable electronics is expected to be one of the most active research areas in the next decade; therefore, nanomaterials possessing high carrier mobility, optical transparency, mechanical robustness and flexibility, lightweight, and environmental stability will be in immense demand. Graphene is one of the nanomaterials that fulfill all these requirements, along with other inherently unique properties and convenience to fabricate into different morphological nanostructures, from atomically thin single layers to nanoribbons. Graphene-based materials have also been investigated in sensor technologies, from chemical sensing to detection of cancer biomarkers. The progress of graphene-based flexible gas and chemical sensors in terms of material preparation, sensor fabrication, and their performance are reviewed here. The article provides a brief introduction to graphene-based materials and their potential applications in flexible and stretchable wearable electronic devices. The role of graphene in fabricating ... more

377 citations

Journal ArticleDOI
Carrie L. Donley1, Darren R. Dunphy1, David C. Paine1, Chet Carter1  +4 moreInstitutions (1)
01 Jan 2002-Langmuir
Abstract: Surface characterization of indium−tin oxide (ITO) thin films has been carried out with monochromatic X-ray photoelectron spectroscopy (XPS) following various solution pretreatments, RF air plasma etching or high-vacuum argon-ion sputtering. Commercially available ITO films show high concentrations of hydrolyzed oxides and oxy-hydroxides in the near-surface region, along with stoichiometric oxide (In2O3, SnO2) and variable levels of oxygen defect sites. XPS revealed that solution and vacuum treatments changed both the relative surface coverage of the hydroxides and, to a lesser extent, the concentration of oxide defect sites in the near-surface region. These pretreatments have a significant effect on both the coverage and electron-transfer rates for chemisorbed ferrocene dicarboxylic acid (Fc(COOH)2), with the air-plasma-etched ITO showing the highest surface coverage of Fc(COOH)2 and an RCA treatment showing the highest electron-transfer rates. more

329 citations

Journal ArticleDOI
Giovanni Neri1Institutions (1)
05 Jan 2015-
Abstract: The first fifty years of chemoresistive sensors for gas detection are here reviewed, focusing on the main scientific and technological innovations that have occurred in the field over the course of these years. A look at advances made in fundamental and applied research and leading to the development of actual high performance chemoresistive devices is presented. The approaches devoted to the synthesis of novel semiconducting materials with unprecedented nanostructure and gas-sensing properties have been also presented. Perspectives on new technologies and future applications of chemoresistive gas sensors have also been highlighted. more

260 citations