Kinetics of defect formation in chemically vapor deposited (CVD) graphene during laser irradiation: The case of Raman investigation

Amato, Giampiero; Milano, Gianluca; Vignolo, Umberto; Vittone, E.

doi:10.1007/s12274-015-0900-1

Cited by 20 publications

(23 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2b ) . We find an asymmetric distribution of I D /I G ratios with a tail towards higher defectiveness that had been previously attributed to the modification of metastable bonds in graphene under laser irradiation during mapping 18 – 22 . It had been suggested that the observed defect distribution is a product of the original defect concentration and a time-dependent increase in defect concentration during Raman mapping.…”

Section: Resultssupporting

confidence: 61%

Impact of growth rate on graphene lattice-defect formation within a single crystalline domain

Chin

Lee

Hofmann

et al. 2018

Sci Rep

View full text Add to dashboard Cite

Chemical vapor deposition (CVD) is promising for the large scale production of graphene and other two-dimensional materials. Optimization of the CVD process for enhancing their quality is a focus of ongoing effort and significant progress has been made in decreasing the defectiveness associated with grain boundaries and nucleation spots. However, little is known about the quality and origin of structural defects in the outgrowing lattice which are present even in single-crystalline material and represent the limit of current optimization efforts. We here investigate the formation kinetics of such defects by controlling graphene’s growth rate over a wide range using nanoscale confinements. Statistical analysis of Raman spectroscopic results shows a clear trend between growth rate and defectiveness that is in quantitative agreement with a model where defects are healed preferentially at the growth front. Our results suggest that low growth rates are required to avoid the freezing of lattice defects and form high quality material. This conclusion is confirmed by a fourfold enhancement in graphene’s carrier mobility upon optimization of the growth rate.

show abstract

Section: Resultssupporting

confidence: 61%

Impact of growth rate on graphene lattice-defect formation within a single crystalline domain

Chin

Lee

Hofmann

et al. 2018

Sci Rep

View full text Add to dashboard Cite

show abstract

“…The laser‐irradiation step, as depicted in Figure a, was carried out using a continuous‐wave (CW) laser with a wavelength of 514 nm, which is below the reported ablation threshold for graphene and is in the spectral range where the Au thin film is highly reflective and optically nonabsorbent, in order to avoid damage to the electrodes . The fluence was set at 6.24 × 10 9 J cm −2 , which is higher than the threshold value for the sp 2 CC bond breaking . Since the photon energy of the laser is lower than the binding energy of graphene, the disassembly of these bonds occurs mainly due to the recombination of the photogenerated electron–hole pairs during intense illumination of graphene .…”

Section: Resultsmentioning

confidence: 99%

“…The fluence was set at 6.24 × 10 9 J cm −2 , which is higher than the threshold value for the sp 2 CC bond breaking . Since the photon energy of the laser is lower than the binding energy of graphene, the disassembly of these bonds occurs mainly due to the recombination of the photogenerated electron–hole pairs during intense illumination of graphene . Bonds between the open‐ended C atoms and metal atoms are then feasible through a thermal annealing step .…”

Section: Resultsmentioning

confidence: 99%

Laser‐Assisted Nanowelding of Graphene to Metals: An Optical Approach toward Ultralow Contact Resistance

Keramatnejad

Zhou

et al. 2017

Adv Materials Inter

View full text Add to dashboard Cite

The electrical performance of graphene‐based devices is largely limited by substantial contact resistance at the heterodimensional graphene–metal junctions. A laser‐assisted nanowelding technique is developed to reduce graphene–metal (G–M) contact resistance and improve carrier injection in suspended graphene devices. Selective breakdown of CC bonds and formation of structural defects are realized through laser irradiation at the edges of graphene within the G–M contact regions in order to increase the chemical reactivity of graphene, facilitate G–M bonding, and, therefore, maximize interfacial carrier transportation. Through this method, significantly reduced G–M contact resistances, as low as 2.57 Ω µm are obtained. In addition, it is demonstrated that the location of laser‐induced defects within the contact areas significantly impacts the interfacial properties and the carrier mobility of graphene devices. A fourfold increase in photocurrent is observed in the suspended graphene photodetectors with treated G–M interfaces as compared to ordinary ones. This contact‐free and position‐selective technique minimizes the degradation of the graphene channels and maintains the superior performance of graphene devices, making it a promising approach for reducing G–M resistance in the fabrication of graphene‐based devices.

show abstract

“…Micro-Raman analysis has been performed in a homemade system [ 21 , 22 ]. All acquisitions of Raman spectra were performed with a laser (λ = 532 nm, wavelength) spot diameter of 1 µm and power of P ≈ 2 mW.…”

Section: Methodsmentioning

confidence: 99%

High Temperature Growth of Graphene from Cobalt Volume: Effect on Structural Properties

Amato

2018

Materials

Self Cite

View full text Add to dashboard Cite

Several transition metals other than the largely used Cu and Ni can be, in principle, employed to catalyze carbon precursors for the chemical vapor deposition of graphene, because the thermodynamics of their alloying with carbon is well known. For example, the wealth of information in the Co-C phase diagram can be used to predict the properties of graphene grown in this way. It is, in fact, expected that growth occurs at a temperature higher than in Ni, with beneficial consequences to the mechanical and electronic properties of the final product. In this work, the growth of graphene onto Co film is presented together with an extensive Raman characterization of the structural properties of the material so far obtained. Previous results reporting the full coverage with negligible defective areas, in spite of discontinuities in the underlying metal, are confirmed, together with the occurrence of strain in the graphene sheet. Strain is deeply investigated in this work, in view of possible employment in engineering the material properties. The observed strain is ascribed to the high thermal mismatch with the substrate, even if an effect of the crystallographic transition of Co cannot be excluded.

show abstract

Kinetics of defect formation in chemically vapor deposited (CVD) graphene during laser irradiation: The case of Raman investigation

Cited by 20 publications

References 21 publications

Impact of growth rate on graphene lattice-defect formation within a single crystalline domain

Impact of growth rate on graphene lattice-defect formation within a single crystalline domain

Laser‐Assisted Nanowelding of Graphene to Metals: An Optical Approach toward Ultralow Contact Resistance

High Temperature Growth of Graphene from Cobalt Volume: Effect on Structural Properties

Contact Info

Product

Resources

About