Thermal annealing of graphene to remove polymer residues

Ahn, Youngkun; Kim, Jungyoon; Ganorkar, Shraddha; Kim, Young‐Hwan; Kim, Seong‐Il

doi:10.1166/mex.2016.1272

Cited by 56 publications

(40 citation statements)

References 12 publications

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“…Figure 1b shows how the presence of these polymer residues will significantly reduce the electron transmission of graphene membranes. Although numerous approaches have been proposed to remove these residues, these are often accompanied by degradation of the graphene, as in the case of annealing treatments which show poor selectivity towards polymer-removal, or simply convert the polymer to amorphous carbon [77,78]. Polymer-free transfer approaches have therefore been developed that completely avoid the use of a support that covers the graphene surface [55,79,80].…”

Section: Graphene Transfermentioning

confidence: 99%

2D Material Membranes for Operando Atmospheric Pressure Photoelectron Spectroscopy

Weatherup

2018

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Probing the chemistry that occurs at catalyst interfaces under realistic process conditions is key to the rational design of better materials for industrial catalytic reactions. Ambient pressure X-ray photoelectron spectroscopy, has until recently been limited to pressures two orders of magnitude below atmosphere. However, the development of photoelectron transparent membranes based on two-dimensional materials that can maintain large pressure differences and yet have thicknesses approaching or even falling below the inelastic mean free path of photoelectrons, now allows the atmospheric pressure regime and above to be accessed. We introduce here the fundamental principles underlying this membrane-based approach to atmospheric pressure photoelectron spectroscopy, and in this context highlight some of the key design concepts and challenges in performing experiments with this technique. We discuss a number of recent proof-of-concept studies, and highlight the potential of the membrane-based approach for operando characterisation of catalyst interfaces under reaction conditions, as well as some current challenges and limitations in this area.

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Section: Graphene Transfermentioning

confidence: 99%

2D Material Membranes for Operando Atmospheric Pressure Photoelectron Spectroscopy

Weatherup

2018

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“…In addition, hydrocarbon impurities are directly absorbed from the atmosphere onto the surface. Their chemical nature is still not precisely known, but most studies point to (‐CH 2 ‐) and (‐CH 3 ‐) groups ; carboxyl, methoxy, and sp 3 ‐hybridized carbon ; and (CO) functional groups . Finally, mobile contamination may be pinned into place by the electron beam .…”

Section: Introductionmentioning

confidence: 99%

Cleaning graphene: Comparing heat treatments in air and in vacuum

Tripathi

Mittelberger

Mustonen

et al. 2017

Physica Rapid Research Ltrs

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Surface impurities and contamination often seriously degrade the properties of two‐dimensional materials such as graphene. To remove contamination, thermal annealing is commonly used. We present a comparative analysis of annealing treatments in air and in vacuum, both ex situ and “pre situ,” where an ultra‐high vacuum treatment chamber is directly connected to an aberration‐corrected scanning transmission electron microscope. While ex situ treatments do remove contamination, it is challenging to obtain atomically clean surfaces after ambient transfer. However, pre situ cleaning with radiative or laser heating appears reliable and well suited to clean graphene without damage to most suspended areas. Pre situ annealing of typical dirty graphene samples yields atomically clean areas several hundred nm2 in size.

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“…The similar change of these new bands in the Raman spectrum of PMMA-transferred graphene upon thermal annealing has been previously reported [143,144,146]. These new bands cannot be removed by further increasing the annealing temperature and duration, indicating that a new type of carbon residues is left after the removal of PMMA residue by thermal annealing [144,146].…”

Section: Degradation Of Pmma Residue Upon Thermal Annealingsupporting

confidence: 83%

Development of a Synthetic Pathway Toward a Bowl-Shaped C 27H12 Polycyclic Aromatic Hydrocarbon

Sun¹

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Study on Electrolyte-gated Graphene Biosensors for Biomarker Detection Jianbo Sun Biosensors are called upon to provide valuable benefits for human society in vital fields such as disease diagnosis, food inspection, environment monitoring, etc. Among the various biosensor architectures, the field effect transistor (FET) biosensors are promising as the next generation nanoelectronic biosensors, particularly attractive for point-of-care biomedical applications. The FET biosensors typically operate by measuring the conductance change of the semiconducting channel induced by the adsorption of the target biomolecules on it. The superior properties of graphene, including the unique electronic characteristics, facile functionalization and good biocompatibility, etc., make it an ideal building block for the FET biosensors. In this dissertation, we present studies on the electrolyte-gated graphene field effect transistor (EGGFET) biosensor and its application for the label-free detection of biomarkers. Poly(methyl methacrylate) (PMMA) residues have long been a critical challenge for the transfer of the chemical vapor deposited (CVD) graphene, which is critical to obtain reliable devices. To address this issue, we first studied the degradation of the PMMA residues upon thermal annealing using Raman spectroscopy. An electrolytic cleaning method is shown to be effective to remove these post-annealing residues, resulting in a clean, residue-free graphene surface. The performance of the EGGFET biosensor is demonstrated by the successful detection of human immunoglobulin G (IgG) using IgG-aptamer as the bioreceptor. The gate voltage with the minimum conductivity (Dirac) in the transfer curve of the EGGFET biosensor is used for the quantitative measurement of IgG concentration. In EGGFET biosensors, the graphene channels are directly exposed to the electrolytes, of which the composition, concentration and pH may vary during the testing. The response of the EGGFET biosensors is found to be susceptible to these variations which might lead to high uncertainty or even false results. We present an EGGFET immunoassay which allows well regulation over the matrix effect. The performance is demonstrated by the detection of human IgG from serum. The detection range of the EGGFET immunoassay for IgG detection is estimated to be around 2-50 nM with a coefficient of variation (CV) of less than 20%. The limit of detection (LOD) is around 0.7 nM. Different from the metal-oxide-semiconductor field effect transistors (MOSFET), the gate voltage is applied on the electrolyte and the electrical double layer (EDL) at the electrolyte-graphene interface serves as the gate dielectric in EGGFET. We studied the capacitance behavior of the electrolyte-graphene interface; the results suggest that the electrolyte-graphene interface exhibits a complex constant phase element (CPE) behavior (1 = 0 ()) with both 0 and varying as functions of the gate voltage. The EDL capacitance and the quantum capacitance are determined which allows us to extract the carrier d...

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Thermal annealing of graphene to remove polymer residues

Cited by 56 publications

References 12 publications

2D Material Membranes for Operando Atmospheric Pressure Photoelectron Spectroscopy

2D Material Membranes for Operando Atmospheric Pressure Photoelectron Spectroscopy

Cleaning graphene: Comparing heat treatments in air and in vacuum

Development of a Synthetic Pathway Toward a Bowl-Shaped C 27H12 Polycyclic Aromatic Hydrocarbon

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