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Value-added Synthesis of Graphene: Recycling Industrial Carbon Waste into Electrodes for High-Performance Electronic Devices.

Seo HK, Kim TS, Park C, Xu W, Baek K, Bae SH, Ahn JH, Kim K, Choi HC, Lee TW - Sci Rep (2015)

Bottom Line: We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates.To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm(2)·V(-1)·s(-1)), without using any physical transfer process.This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk 790-784, Republic of Korea.

ABSTRACT
We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates. The method, which does not require an additional transfer process, enables direct growth of graphene films on device substrates in large area. To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm(2)·V(-1)·s(-1)), without using any physical transfer process. This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.

No MeSH data available.


(a) Transfer characteristics of graphene-electrode pentacene FET (red: forward bias, black: reverse bias). (b) Photograph of large-area Gr-P FET array of 144 devices on a 4-inch wafer (inset, histogram of the field effect mobility μFET).
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f5: (a) Transfer characteristics of graphene-electrode pentacene FET (red: forward bias, black: reverse bias). (b) Photograph of large-area Gr-P FET array of 144 devices on a 4-inch wafer (inset, histogram of the field effect mobility μFET).

Mentions: The electrical properties of the fabricated bottom contact graphene-electrode pentacene FETs (Gr-P FETs) (Fig. 4b, inset) were characterized by measuring their output and transfer characteristics (Fig. 4b,c). For comparison, bottom contact Au-electrode pentacene FETs (Au-P FETs) were fabricated on 500 nm SiO2/Si substrates. The output characteristics of the two types of FETs were measured under different linear and saturation current levels (Fig. 4b). The Gr-P FETs showed a clear gating effect and ohmic contact, but Au-P FETs did not have ohmic contact and had low output currents, due to the high contact resistance RC between Au and pentacene (Figure S6). We calculated RC of Gr-P and Au-P FETs by using the transfer line method with channel lengths of 30, 50, 80, and 100 μm (Figure S7). As gate voltage varied from −60 to −150 V, RC of the graphene electrode, normalized by channel width (1500 μm), decreased from 0.14 MΩ·cm to 0.043 MΩ·cm (Fig. 4d), which is about two orders of magnitude lower than that of the Au electrode. This result is consistent with previous reports which demonstrated better FET performance in graphene-electrodes than in common metal electrodes54555657. Gr-P FETs showed transfer characteristics typical of p-type FETs (Fig. 4c). Calculated field-effect mobility μFET in the saturation regime was an order of magnitude higher in Gr-P FETs (0.05–0.13 cm2·V−1·s−1) than in Au-P FETs (0.011–0.017 cm2·V−1·s−1). The transfer curve of the Gr-P FETs showed a high on/off current ratio (1.1 × 107) with small hysteresis (Fig. 5a), so they are suitable for use in circuits and switches of active electronic devices. Our graphene synthesis method enables fabrication of large-area devices; we achieved a large-area Gr-P FETs array of 144 devices on a 4-inch wafer (Fig. 5b, inset). In this case, the fabrication process was the same as used to fabricate the Gr-P FETs, except for the use of the large area substrate. The distribution of the μFET of the Gr-P FET large-area arrays showed ~95% operation and maximum μFET 0.13 cm2·V−1·s−1 (average μFET ~0.07 cm2·V−1·s−1) (Fig. 5b).


Value-added Synthesis of Graphene: Recycling Industrial Carbon Waste into Electrodes for High-Performance Electronic Devices.

Seo HK, Kim TS, Park C, Xu W, Baek K, Bae SH, Ahn JH, Kim K, Choi HC, Lee TW - Sci Rep (2015)

(a) Transfer characteristics of graphene-electrode pentacene FET (red: forward bias, black: reverse bias). (b) Photograph of large-area Gr-P FET array of 144 devices on a 4-inch wafer (inset, histogram of the field effect mobility μFET).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644944&req=5

f5: (a) Transfer characteristics of graphene-electrode pentacene FET (red: forward bias, black: reverse bias). (b) Photograph of large-area Gr-P FET array of 144 devices on a 4-inch wafer (inset, histogram of the field effect mobility μFET).
Mentions: The electrical properties of the fabricated bottom contact graphene-electrode pentacene FETs (Gr-P FETs) (Fig. 4b, inset) were characterized by measuring their output and transfer characteristics (Fig. 4b,c). For comparison, bottom contact Au-electrode pentacene FETs (Au-P FETs) were fabricated on 500 nm SiO2/Si substrates. The output characteristics of the two types of FETs were measured under different linear and saturation current levels (Fig. 4b). The Gr-P FETs showed a clear gating effect and ohmic contact, but Au-P FETs did not have ohmic contact and had low output currents, due to the high contact resistance RC between Au and pentacene (Figure S6). We calculated RC of Gr-P and Au-P FETs by using the transfer line method with channel lengths of 30, 50, 80, and 100 μm (Figure S7). As gate voltage varied from −60 to −150 V, RC of the graphene electrode, normalized by channel width (1500 μm), decreased from 0.14 MΩ·cm to 0.043 MΩ·cm (Fig. 4d), which is about two orders of magnitude lower than that of the Au electrode. This result is consistent with previous reports which demonstrated better FET performance in graphene-electrodes than in common metal electrodes54555657. Gr-P FETs showed transfer characteristics typical of p-type FETs (Fig. 4c). Calculated field-effect mobility μFET in the saturation regime was an order of magnitude higher in Gr-P FETs (0.05–0.13 cm2·V−1·s−1) than in Au-P FETs (0.011–0.017 cm2·V−1·s−1). The transfer curve of the Gr-P FETs showed a high on/off current ratio (1.1 × 107) with small hysteresis (Fig. 5a), so they are suitable for use in circuits and switches of active electronic devices. Our graphene synthesis method enables fabrication of large-area devices; we achieved a large-area Gr-P FETs array of 144 devices on a 4-inch wafer (Fig. 5b, inset). In this case, the fabrication process was the same as used to fabricate the Gr-P FETs, except for the use of the large area substrate. The distribution of the μFET of the Gr-P FET large-area arrays showed ~95% operation and maximum μFET 0.13 cm2·V−1·s−1 (average μFET ~0.07 cm2·V−1·s−1) (Fig. 5b).

Bottom Line: We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates.To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm(2)·V(-1)·s(-1)), without using any physical transfer process.This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk 790-784, Republic of Korea.

ABSTRACT
We have developed a simple, scalable, transfer-free, ecologically sustainable, value-added method to convert inexpensive coal tar pitch to patterned graphene films directly on device substrates. The method, which does not require an additional transfer process, enables direct growth of graphene films on device substrates in large area. To demonstrate the practical applications of the graphene films, we used the patterned graphene grown on a dielectric substrate directly as electrodes of bottom-contact pentacene field-effect transistors (max. field effect mobility ~0.36 cm(2)·V(-1)·s(-1)), without using any physical transfer process. This use of a chemical waste product as a solid carbon source instead of commonly used explosive hydrocarbon gas sources for graphene synthesis has the dual benefits of converting the waste to a valuable product, and reducing pollution.

No MeSH data available.