Conformal Liquid-Metal Electrodes for Flexible Graphene Device Interconnects

Ordonez, Richard C.; Hayashi, Cody K.; Torres, C.M Sotomayor; Hafner, Noah; Adleman, James R.; Acosta, Noah; Melcher, Jordan; Kamin, Nackieb; Garmire, David

doi:10.1109/ted.2016.2599879

Cited by 15 publications

(16 citation statements)

References 18 publications

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“…Galinstan is a non-toxic liquid-metal alloy consisting of 68.5% gallium, 21.5% indium, and 10% tin 14 that possesses desirable conformal properties. In a previous study, Galinstan device interconnects exhibited less than a 5.5% change in resistance for a graphene two-terminal device when subjected to repeated deformations as small as 4.5 mm radius of curvature 15 . Moreover, graphene transistors can greatly benefit from the conductivity of Galinstan (2.30 × 10 6 S / m ), a desirable vapor pressure (<1 × 10 −6 Pa at 500 ° C ) compared with mercury (0.1713 Pa at 20 ° C ), and a stable liquid state across a broad temperature range (−19 ° C to 1300 ° C ) 16 .…”

Section: Introductionmentioning

confidence: 85%

Rapid Fabrication of Graphene Field-Effect Transistors with Liquid-metal Interconnects and Electrolytic Gate Dielectric Made of Honey

Ordonez

Hayashi

Torres

et al. 2017

Sci Rep

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Historically, graphene-based transistor fabrication has been time-consuming due to the high demand for carefully controlled Raman spectroscopy, physical vapor deposition, and lift-off processes. For the first time in a three-terminal graphene field-effect transistor embodiment, we introduce a rapid fabrication technique that implements non-toxic eutectic liquid-metal Galinstan interconnects and an electrolytic gate dielectric comprised of honey. The goal is to minimize cost and turnaround time between fabrication runs; thereby, allowing researchers to focus on the characterization of graphene phenomena that drives innovation rather than a lengthy device fabrication process that hinders it. We demonstrate characteristic Dirac peaks for a single-gate graphene field-effect transistor embodiment that exhibits hole and electron mobilities of 213 ± 15 and 166 ± 5 cm 2/V·s respectively. We discuss how our methods can be used for the rapid determination of graphene quality and can complement Raman Spectroscopy techniques. Lastly, we explore a PN junction embodiment which further validates that our fabrication techniques can rapidly adapt to alternative device architectures and greatly broaden the research applicability.

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Section: Introductionmentioning

confidence: 85%

Rapid Fabrication of Graphene Field-Effect Transistors with Liquid-metal Interconnects and Electrolytic Gate Dielectric Made of Honey

Ordonez

Hayashi

Torres

et al. 2017

Sci Rep

Self Cite

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“…Recent research in flexible electronics has explored the utilization of two-dimensional graphene in thin-film devices due to its high carrier mobility, high tensile strength, and broadband sensing capability [ 3 , 4 ]. Graphene is defined as a monolayer of carbon atoms arranged in a hexagonal lattice with a bond length of 1.42 Å and a lattice constant of 2.46 Å [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Polar Organic Gate Dielectrics for Graphene Field-Effect Transistor-Based Sensor Technology

Kam

Tengan

Hayashi

et al. 2018

Sensors

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We have pioneered the use of liquid polar organic molecules as alternatives to rigid gate-dielectrics for the fabrication of graphene field-effect transistors. The unique high net dipole moment of various polar organic molecules allows for easy manipulation of graphene’s conductivity due to the formation of an electrical double layer with a high-capacitance at the liquid and graphene interface. Here, we compare the performances of dimethyl sulfoxide (DMSO), acetonitrile, propionamide, and valeramide as polar organic liquid dielectrics in graphene field-effect transistors (GFETs). We demonstrate improved performance for a GFET with a liquid dielectric comprised of DMSO with high electron and hole mobilities of 154.0 cm2/Vs and 154.6 cm2/Vs, respectively, and a Dirac voltage <5 V.

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“…In contrast to conventional metals, sp 2 -bonded carbon materials are stable to alloy formation with liquid metals. [25,26] To leverage this property in a platform that is suitable for printed GaLMAs, graphene inks based on cellulose derivatives are used for robust contacts to liquid metal. This class of graphene inks has shown broad process compatibility with excellent electrical conductivity, mechanical durability, and environmental stability.…”

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confidence: 99%

Wiring up Liquid Metal: Stable and Robust Electrical Contacts Enabled by Printable Graphene Inks

Secor

Cook

Tabor

et al. 2017

Adv Elect Materials

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electronic materials. By leveraging these unique characteristics, researchers have recently demonstrated advances in reconfigurable, responsive, and stretchable electronic devices. [5][6][7][8] Select applications of liquid metals include soft electronic skins, [9,10] dynamic and flexible antennas, [11][12][13][14] and self-healing and elastic electronics. [15,16] Moreover, the fluid nature of GaLMAs such as eutectic gallium-indium (eGaIn) enables broad process compatibility with additive printing methods such as direct write, inkjet, transfer, and 3D printing. [17][18][19][20][21][22][23] As such, research toward the control and integration of GaLMAs for printed, stretchable, and reconfigurable electronics has attracted broad scientific and practical interest.Despite their promise, the development of liquid metal electronics must overcome several challenges for widespread application. In particular, stable electrical contacts have been identified as a critical challenge for the integration of GaLMAs in electronic circuits and systems. [4] Since gallium alloys rapidly with most metals, GaLMAs lead to unstable or mechanically sensitive interfaces when combined with metal electrodes or interconnects, thereby preventing the reliable integration of eGaIn functionality with conventional electronics. In a recent dramatic demonstration of this effect, Dickey and coworkers exploited the aggressive alloying of eGaIn with silver to direct the motion of liquid metal droplets across a surface, completely removing the silver in the process. [24] Therefore, to enable broader application of eGaIn with conventional circuits, interfacial alloying needs to be suppressed without compromising electrical or mechanical properties.Here, we demonstrate printed graphene as a reliable and high-performance interfacial layer to enable electrical connections to eGaIn. In contrast to conventional metals, sp 2 -bonded carbon materials are stable to alloy formation with liquid metals. [25,26] To leverage this property in a platform that is suitable for printed GaLMAs, graphene inks based on cellulose derivatives are used for robust contacts to liquid metal. This class of graphene inks has shown broad process compatibility with excellent electrical conductivity, mechanical durability, and environmental stability. [27][28][29][30] A thin film (≈100 nm) of fewlayer graphene flakes printed between conventional silver leads and eGaIn acts as a physical barrier, effectively passivating the surface against alloying while retaining the ability to conduct current across the interface. Moreover, graphene interfacial Gallium-based liquid metal alloys (GaLMAs) are a unique class of advanced materials with the potential to offer unprecedented opportunities in stretchable and reconfigurable electronics. Despite their promise, the development of liquid metal electronics must overcome several challenges for widespread application. In particular, stable electrical contacts have been identified as a critical challenge for the integration of GaLMAs in electronic...

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Conformal Liquid-Metal Electrodes for Flexible Graphene Device Interconnects

Cited by 15 publications

References 18 publications

Rapid Fabrication of Graphene Field-Effect Transistors with Liquid-metal Interconnects and Electrolytic Gate Dielectric Made of Honey

Rapid Fabrication of Graphene Field-Effect Transistors with Liquid-metal Interconnects and Electrolytic Gate Dielectric Made of Honey

Polar Organic Gate Dielectrics for Graphene Field-Effect Transistor-Based Sensor Technology

Wiring up Liquid Metal: Stable and Robust Electrical Contacts Enabled by Printable Graphene Inks

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