Time Evolution Studies on Strain and Doping of Graphene Grown on a Copper Substrate Using Raman Spectroscopy

Lee, Ukjae; Han, Yoojoong; Lee, Sanghyub; Kim, Jun Suk; Lee, Young Hee; Kim, Un Jeong; Son, Hyungbin

doi:10.1021/acsnano.9b08205

Cited by 56 publications

(41 citation statements)

References 56 publications

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“…The changes were known being more significant for the graphene structures exposed to gases such as NH 3 , CO, H 2 O and NO 2 [6]. There were reported attempts in literature [9][10][11] focused on understanding of the long-time stability problems. In [9], the changes in properties over time were described for the graphene sheets grown on the Cu substrate.…”

Section: Introductionmentioning

confidence: 99%

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Long-time drift induced changes in electrical characteristics of graphene–metal contacts

Sakavičius¹,

Agafonov²,

Bukauskas³

et al. 2020

Lith. J. Phys.

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Chemical vapour deposition (CVD) graphene is commonly recognized as promising 2D material for development of electronic devices. However, the long-term drift of electrical parameters still requires deeper understanding before the technological means can be selected for an individual type of the devices. In this work, the changes in the electrical resistance were investigated over long time in the planar samples based on the CVD graphene with Au and Ni contacts. The samples were arranged as arrays of the resistors on a silicon substrate covered with a 250 nm layer of thermally grown silicon dioxide. The annealing in pure argon gas flow at 573 K was used to return the electrical properties of samples to the initial state. The effects of drift and annealing were compared for the three parts of structures, namely the electrical contact, the graphene sheet and the edge of the metal film with a hanging graphene sheet. For these parts, the resistance changes were related to the strain and doping of supported and hanged parts of the graphene sheet. Raman spectroscopy and Kelvin force probe microscopy were used to characterize charge doping, strain and work function in the graphene. The drift was explained in terms of the most prominent changes in the doping, strain and work function detected within the edge zone of the contact. It was proved that the annealing significantly changed the p-type doping and work function in the graphene layer in this edge zone. The properties were almost independent of test conditions in the SiO2 supported graphene. The changes in the contact parameters produced by drift mechanisms were proved being reversible under proper annealing conditions.

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Section: Introductionmentioning

confidence: 99%

“…There were reported attempts in literature [9][10][11] focused on understanding of the long-time stability problems. In [9], the changes in properties over time were described for the graphene sheets grown on the Cu substrate. An influence of the atmosphere was explained for the graphene sheets in Refs.…”

Section: Introductionmentioning

confidence: 99%

Long-time drift induced changes in electrical characteristics of graphene–metal contacts

Sakavičius¹,

Agafonov²,

Bukauskas³

et al. 2020

Lith. J. Phys.

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“…It is important to note that various studies have suggested that the values of ω G and ω 2D cannot be explained solely by charge doping and strain [ 67 ], and that variations in the Fermi velocity can alter the ω 2 D without affecting the ω G [ 61 , 68 ]. Finally, previous studies on the oxidation of graphene on Cu surfaces have attributed red-shifts in ω D , ω G and ω 2 D to strain release after oxidation, as mentioned previously, which augment with the growth of the oxide underlayer [ 20 , 48 ] producing corrugation and wrinkling in the graphene sheet [ 69 ]. In all these cases, characteristic Raman bands of copper oxides were clearly observed, where the strongest bands expected for Cu 2 O at 148, 219 and 635 cm -1 , and CuO at 273, 327 and 619 cm -1 [ 70 , 71 ].…”

Section: Resultsmentioning

confidence: 69%

Oxygen intercalation in PVD graphene grown on copper substrates: A decoupling approach

Azpeitia

Palacio

Martínez

et al. 2020

Applied Surface Science

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We investigate the intercalation process of oxygen in-between a PVD-grown graphene layer and different copper substrates as a methodology for reducing the substrate-layer interaction. This growth method leads to an extended defect-free graphene layer that strongly couples with the substrate. We have found, by means of X-ray photoelectron spectroscopy, that after oxygen exposure at different temperatures, ranging from 280 °C to 550 °C, oxygen intercalates at the interface of graphene grown on Cu foil at an optimal temperature of 500 °C. The low energy electron diffraction technique confirms the adsorption of an atomic oxygen adlayer on top of the Cu surface and below graphene after oxygen exposure at elevated temperature, but no oxidation of the substrate is induced. The emergence of the 2D Raman peak, quenched by the large interaction with the substrate, reveals that the intercalation process induces a structural undoing. As suggested by atomic force microscopy, the oxygen intercalation does not change significantly the surface morphology. Moreover, theoretical simulations provide further insights into the electronic and structural undoing process. This protocol opens the door to an efficient methodology to weaken the graphene-substrate interaction for a more efficient transfer to arbitrary surfaces.

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“…[53] By plotting the G-band (ω G ) against the 2D-band (ω 2D ) frequencies using the Raman maps in Figure S6, Supporting Information, vector analysis on strain and doping was conducted depending on the transfer methods in Figure 6. [54,55] Incremental strain and doping levels (i.e., 0.1% and 5 × 10 12 cm −2 , respectively) are marked in black and pink horizontal lines along two unit vector directions, e H and e T . Interestingly, four samples display different characteristics in doping and strain status.…”

Section: Figure 2amentioning

confidence: 99%

Facile Morphological Qualification of Transferred Graphene by Phase‐Shifting Interferometry

et al. 2020

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Post‐growth graphene transfer to a variety of host substrates for circuitry fabrication has been among the most popular subjects since its successful development via chemical vapor deposition in the past decade. Fast and reliable evaluation tools for its morphological characteristics are essential for the development of defect‐free transfer protocols. The implementation of conventional techniques, such as Raman spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy in production quality control at an industrial scale is difficult because they are limited to local areas, are time consuming, and their operation is complex. However, through a one‐shot measurement within a few seconds, phase‐shifting interferometry (PSI) successfully scans ≈1 mm2 of transferred graphene with a vertical resolution of ≈0.1 nm. This provides crucial morphological information, such as the surface roughness derived from polymer residues, the thickness of the graphene, and its adhesive strength with respect to the target substrates. Graphene samples transferred via four different methods are evaluated using PSI, Raman spectroscopy, and AFM. Although the thickness of the nanomaterials measured by PSI can be highly sensitive to their refractive indices, PSI is successfully demonstrated to be a powerful tool for investigating the morphological characteristics of the transferred graphene for industrial and research purposes.

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Time Evolution Studies on Strain and Doping of Graphene Grown on a Copper Substrate Using Raman Spectroscopy

Cited by 56 publications

References 56 publications

Long-time drift induced changes in electrical characteristics of graphene–metal contacts

Long-time drift induced changes in electrical characteristics of graphene–metal contacts

Oxygen intercalation in PVD graphene grown on copper substrates: A decoupling approach

Facile Morphological Qualification of Transferred Graphene by Phase‐Shifting Interferometry

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