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Fabrication of graphene films with high transparent conducting characteristics.

Ma X, Zhang H - Nanoscale Res Lett (2013)

Bottom Line: It was found that the graphene films present excellent electrical conductivity with high transparency.The conductivity is up to 1,240 S/cm, the sheet resistance is lower than 1 kΩ/sq, and the transparency is well over 85% in the visible wavelength range of 400 to 800 nm, showing that the graphene films have very low resistivity and superior transparency and completely satisfy the need for transparent conductors.PACS: 61.48.+c, 78.67.Pt, 68.37.Hk, 68.65.Ac.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Mathematics and Physics, Suzhou University of Science and Technology, 1# Kerui Road, Suzhou, Jiangsu 215009, China. maxy@mail.usts.edu.cn.

ABSTRACT
We present a study on the transparent conducting characteristics of graphene-based films prepared by means of rapid chemical vapor deposition. The graphene films were grown on quartz slides with a CH4/Ar mixed gas under a constant flow at 950°C and then annealed at 1,000°C. It was found that the graphene films present excellent electrical conductivity with high transparency. The conductivity is up to 1,240 S/cm, the sheet resistance is lower than 1 kΩ/sq, and the transparency is well over 85% in the visible wavelength range of 400 to 800 nm, showing that the graphene films have very low resistivity and superior transparency and completely satisfy the need for transparent conductors. These properties can be used in many applications, such as transparent conductor films for touch panels. PACS: 61.48.+c, 78.67.Pt, 68.37.Hk, 68.65.Ac.

No MeSH data available.


The Raman spectra of the graphene films. A 2D band peak at 2,692 cm-1 and a G band peak at 1,580 cm-1 are shown. The intensity ratio of the 5 min sample is ID/IG = 2.8.
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Figure 3: The Raman spectra of the graphene films. A 2D band peak at 2,692 cm-1 and a G band peak at 1,580 cm-1 are shown. The intensity ratio of the 5 min sample is ID/IG = 2.8.

Mentions: Figure 3 shows the Raman spectra of the graphene films. We can see that two major scattering peaks appear in the spectrum: a 2D band peak at 2,692 cm-1 and a G band peak at 1,580 cm-1. It is well known that the G band indicates a sound graphite carbon structure (sp2) whereas the 2D band is a typical band of graphene [23]. The disorder-induced D band (at approximately 1,350 cm-1) was not seen in the first-order Raman spectra. The intensity ratio of D band (ID) to G band (IG) can be used as an indication of defect quantity: a low ID/IG corresponds to a small defect quantity. The absent D band in the Raman spectra shows that the deposited graphene in our samples has high quality. The sharp 2D peak in graphene is roughly three times (the largest intensity ratio of I2D/IG = 2.8) more intense than the G peak, suggesting that the quality of the deposited graphene is comparable to that of graphene grown on foils [24]. The main growth mechanism of graphene on SiO2 with a good quality may be attributed to carbon atoms from pyrolysis of CH4 in the self-assembly adsorption process. Sun et al. [25] reported that carbon atoms readily arrange themselves in aromatic rings and planar sp2-hybridized graphitic layers forming nanographene on a high-temperature substrate. The second mechanism is the promotion of oxygen. Since the reactive chamber has a low ultimate vacuum pressure (about 10-2 Pa) in our experiment, the remaining oxygen in the tube and the high substrate temperature will promote adsorption of carbon atoms onto the quartz slide. Chen et al. [26] found that the presence of oxygen can enhance the capture of CHx fragments through C-O and H-O binding and thus provides more opportunities for C-C coupling and graphene nucleation. Moreover, during deposition of graphene films on SiO2, we placed some nanoscaled Ni powder on the Si substrates in the tube to measure the electrical junction properties of graphene/Si. A few Ni nanoparticles on the Si substrates were carried on the quartz surface by CH4 and Ar gases, which accelerated the carbon atoms adhering and growing on the quartz, similar to that of graphene grown on Cu but not to graphene grown on Ni which occurs by a C segregation or precipitation process [21].


Fabrication of graphene films with high transparent conducting characteristics.

Ma X, Zhang H - Nanoscale Res Lett (2013)

The Raman spectra of the graphene films. A 2D band peak at 2,692 cm-1 and a G band peak at 1,580 cm-1 are shown. The intensity ratio of the 5 min sample is ID/IG = 2.8.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016024&req=5

Figure 3: The Raman spectra of the graphene films. A 2D band peak at 2,692 cm-1 and a G band peak at 1,580 cm-1 are shown. The intensity ratio of the 5 min sample is ID/IG = 2.8.
Mentions: Figure 3 shows the Raman spectra of the graphene films. We can see that two major scattering peaks appear in the spectrum: a 2D band peak at 2,692 cm-1 and a G band peak at 1,580 cm-1. It is well known that the G band indicates a sound graphite carbon structure (sp2) whereas the 2D band is a typical band of graphene [23]. The disorder-induced D band (at approximately 1,350 cm-1) was not seen in the first-order Raman spectra. The intensity ratio of D band (ID) to G band (IG) can be used as an indication of defect quantity: a low ID/IG corresponds to a small defect quantity. The absent D band in the Raman spectra shows that the deposited graphene in our samples has high quality. The sharp 2D peak in graphene is roughly three times (the largest intensity ratio of I2D/IG = 2.8) more intense than the G peak, suggesting that the quality of the deposited graphene is comparable to that of graphene grown on foils [24]. The main growth mechanism of graphene on SiO2 with a good quality may be attributed to carbon atoms from pyrolysis of CH4 in the self-assembly adsorption process. Sun et al. [25] reported that carbon atoms readily arrange themselves in aromatic rings and planar sp2-hybridized graphitic layers forming nanographene on a high-temperature substrate. The second mechanism is the promotion of oxygen. Since the reactive chamber has a low ultimate vacuum pressure (about 10-2 Pa) in our experiment, the remaining oxygen in the tube and the high substrate temperature will promote adsorption of carbon atoms onto the quartz slide. Chen et al. [26] found that the presence of oxygen can enhance the capture of CHx fragments through C-O and H-O binding and thus provides more opportunities for C-C coupling and graphene nucleation. Moreover, during deposition of graphene films on SiO2, we placed some nanoscaled Ni powder on the Si substrates in the tube to measure the electrical junction properties of graphene/Si. A few Ni nanoparticles on the Si substrates were carried on the quartz surface by CH4 and Ar gases, which accelerated the carbon atoms adhering and growing on the quartz, similar to that of graphene grown on Cu but not to graphene grown on Ni which occurs by a C segregation or precipitation process [21].

Bottom Line: It was found that the graphene films present excellent electrical conductivity with high transparency.The conductivity is up to 1,240 S/cm, the sheet resistance is lower than 1 kΩ/sq, and the transparency is well over 85% in the visible wavelength range of 400 to 800 nm, showing that the graphene films have very low resistivity and superior transparency and completely satisfy the need for transparent conductors.PACS: 61.48.+c, 78.67.Pt, 68.37.Hk, 68.65.Ac.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Mathematics and Physics, Suzhou University of Science and Technology, 1# Kerui Road, Suzhou, Jiangsu 215009, China. maxy@mail.usts.edu.cn.

ABSTRACT
We present a study on the transparent conducting characteristics of graphene-based films prepared by means of rapid chemical vapor deposition. The graphene films were grown on quartz slides with a CH4/Ar mixed gas under a constant flow at 950°C and then annealed at 1,000°C. It was found that the graphene films present excellent electrical conductivity with high transparency. The conductivity is up to 1,240 S/cm, the sheet resistance is lower than 1 kΩ/sq, and the transparency is well over 85% in the visible wavelength range of 400 to 800 nm, showing that the graphene films have very low resistivity and superior transparency and completely satisfy the need for transparent conductors. These properties can be used in many applications, such as transparent conductor films for touch panels. PACS: 61.48.+c, 78.67.Pt, 68.37.Hk, 68.65.Ac.

No MeSH data available.