Highly enhanced sensitivity of hydrogen sensors using novel palladium-decorated graphene nanoribbon film/SiO<sub>2</sub>/Si structures

Zhang, Zhongyang; Du, Yonggang; Ling, Cuicui; Xing, Wei

doi:10.1039/c4ta02581d

Cited by 32 publications

(28 citation statements)

References 42 publications

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“…Hence, at low relative humidity, in the thermally treated MWCNTs/PVP film sensor, when a few water molecules were adsorbed by PVP to generate a few H + and H 3 O + , the ions carriers (H + and H 3 O + ) injected into n‐type PVP to neutralize intrinsic electrons of PVP to weaken the barrier of n–p heterojunctions and decrease the resistance of heterojunctions, especially the backward resistance ( R n–p ), which caused that the resistance of sensor apparently decreased. A similar phenomenon of heterojunction has been reported . So the thermally treated MWCNTs/PVP film sensor could work efficiently and exhibit better sensitivity at low RH.…”

Section: Resultssupporting

confidence: 73%

Effective Enhancement of Humidity Sensing Characteristics of Novel Thermally Treated MWCNTs/Polyvinylpyrrolidone Film Caused by Interfacial Effect

Pan

Zhang

Guo

et al. 2016

Adv Materials Inter

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Multi-walled carbon nanotubes (MWCNTs)/hydrophilic poly(vinylpyrrolidone) (PVP) fi lms are prepared by a simple spin-coating method and the resistive humidity sensing properties of the fi lms are studied in detail. It is demonstrated that the thermally treated MWCNTs/PVP fi lm exhibits a reproducible and great response over a wide relative humidity range from 11% to 94%, fast response time (less than 15 s) and ultrafast recovery time (less than 1.8 s), which are superior to that of pristine PVP fi lms. The effective enhancement of humidity sensing characteristics of MWCNTs/PVP fi lms can be explained by the MWCNTs/PVP interfacial effect. The thermally treated MWCNTs/PVP fi lms can be used as robust, cost-effective, and easy-to-use resistive humidity sensors. And the design concept used in this work can be extended to other carbon composites to fabricate excellent sensing materials for sensors.

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Section: Resultssupporting

confidence: 73%

Effective Enhancement of Humidity Sensing Characteristics of Novel Thermally Treated MWCNTs/Polyvinylpyrrolidone Film Caused by Interfacial Effect

Pan

Zhang

Guo

et al. 2016

Adv Materials Inter

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“…At +0.15 V, the current value increases from 1.4×10 -2 mA to 1.1×10 -1 mA and the S reached ~685.7%. This sensitivity is much larger than other reported results [50][51][52].…”

Section: Resultscontrasting

confidence: 61%

High hydrogen sensitivity of vertically standing layered MoS2/Si heterojunctions

Hao

Liu

Gao

et al. 2016

Journal of Alloys and Compounds

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Molybdenum disulfide (MoS 2) thin films are deposited onto silicon (Si) substrates using magnetron sputtering technique. Raman spectra show that the out-of-plane vibration is preferentially excited for the film. X-ray diffraction patterns further illustrate that the deposited MoS 2 films have the preferential [100] orientation. These results demonstrate that the unit layers of S-Mo-S in the film are perpendicular to the substrate. This can supply high-speed paths for the transportation of the electron carriers along the out-of-plane orientation. Due to the unique vertically standing layered structure of the MoS 2 film, the fabricated MoS 2 /Si sensor device exhibits excellent hydrogen (H 2) sensing properties. The device performance can be featured by a high sensitivity (687.3% under 100.0 ppm H 2), high detection resolution (a 1.0-ppm level), as well as fast response and recovery, and good reversibility. The sensing mechanisms were discussed based on the microstructural characteristics of the MoS 2 film and the energy-band alignment near the MoS 2 /Si interface. The MoS 2 /Si heterojunctions proposed in this work might open new avenues for the development of future high-performance sensor devices.

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“…17 Contact resistance in graphene devices has being extensively investigated. [3][4][5]10,18,19 It is known that graphene devices produced in a Hall bar geometry (non-invasive contacts) show a more symmetrical conductance dependence with the gate voltage in both electron and hole branches.…”

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confidence: 99%

Metal-graphene heterojunction modulation via H2 interaction

Cadore

Mania

Morais

et al. 2016

Applied Physics Letters

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Combining experiment and theory, we investigate how a naturally created heterojunction (pn junction) at a graphene and metallic contact interface is modulated via interaction with molecular hydrogen (H2). Due to an electrostatic interaction, metallic electrodes induce pn junctions in graphene, leading to an asymmetrical resistance for electronic transport via electrons and holes. We report that an asymmetry in the resistance can be tuned in a reversible manner by exposing graphene devices to H2. The interaction between the H2 and graphene occurs solely at the graphene-contact pn junction and might be due to a modification on the electrostatic interaction between graphene and metallic contacts. We confront the experimental data with theory providing information concerning the length of the heterojunction, and how it changes as a function of H2 adsorption. Our results are valuable for understanding the nature of the metal-graphene interfaces and point out to a novel route towards selective hydrogen sensor application.Graphene is a zero-gap semiconductor which charge carrier density and conductance can be controlled electrostatically by preparing graphene devices as field effect transistors.1,2 In such architecture, the contact resistance considerably impairs device performance and is responsible for a conduction asymmetry for p-doped and n-doped graphene.3-8 This asymmetry stems from heterojunctions (pn junctions) formed at metal-graphene interfaces due to different work functions between graphene and metal -i.e. Fermi level pinning. 9-13 Effectively, the advent of the pn junction results in an additional charge scattering at the metal-graphene interface increasing device resistance. On the other hand, interesting effects can be observed as well. For instance: heterojunctions at metal-graphene interface have been used to design FabryPerot cavities 11 and to observe resonances in Josephson junctions in graphene devices. 14 In both systems, the metal-graphene interfaces have been considered a static problem, where the doping at the graphene underneath the contact is solely defined by the type of metal used. However, so far, a controllable method to probe and modulate the pn junction induced by contacts has not been reported. In addition, there are still open questions about how far a pn junction can extend from the contact into the graphene channel and if there are technological applications based on specialties of graphene contact resistance. 3,4,6,7,[14][15][16]

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Highly enhanced sensitivity of hydrogen sensors using novel palladium-decorated graphene nanoribbon film/SiO₂/Si structures

Cited by 32 publications

References 42 publications

Effective Enhancement of Humidity Sensing Characteristics of Novel Thermally Treated MWCNTs/Polyvinylpyrrolidone Film Caused by Interfacial Effect

Effective Enhancement of Humidity Sensing Characteristics of Novel Thermally Treated MWCNTs/Polyvinylpyrrolidone Film Caused by Interfacial Effect

High hydrogen sensitivity of vertically standing layered MoS2/Si heterojunctions

Metal-graphene heterojunction modulation via H2 interaction

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Highly enhanced sensitivity of hydrogen sensors using novel palladium-decorated graphene nanoribbon film/SiO2/Si structures

Cited by 32 publications

References 42 publications

Effective Enhancement of Humidity Sensing Characteristics of Novel Thermally Treated MWCNTs/Polyvinylpyrrolidone Film Caused by Interfacial Effect

Effective Enhancement of Humidity Sensing Characteristics of Novel Thermally Treated MWCNTs/Polyvinylpyrrolidone Film Caused by Interfacial Effect

High hydrogen sensitivity of vertically standing layered MoS2/Si heterojunctions

Metal-graphene heterojunction modulation via H2 interaction

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Product

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Highly enhanced sensitivity of hydrogen sensors using novel palladium-decorated graphene nanoribbon film/SiO₂/Si structures