Localized insulator-conductor transformation of graphene oxide thin films via focused laser beam irradiation |
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Authors: | Ye Tao Binni Varghese Manu Jaiswal Shuai Wang Zheng Zhang Barbaros Oezyilmaz Kian Ping Loh Eng Soon Tok Chorng Haur Sow |
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Affiliation: | (1) Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore;(2) Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore;(3) Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 3 Research Link, Singapore, 117602, Singapore; |
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Abstract: | By scanning a focused laser beam over graphene oxide (GO) film deposited on SiO2/Si substrates, conductive strips as small as 1 μm can be patterned directly either as a channel in the insulating matrix, or as a stand-alone micro belt. The conductivity was increased by at least two orders of magnitude with the mobility estimated in the range of 1–10 cm2/V s. Raman mapping and X-ray photoelectron spectroscopy studies demonstrated the reduction of GO in the laser-irradiated area. The conductance of the patterned channel was independent of the change in oxide-electrode contact resistance of the graphene, and increased linearly with increasing channel width. Increasing irradiation power by repeated scanning initially increased the conductivity of the irradiated area and saturated at a conductivity of ∼36 S/cm. Partial oxidative burning combined with photothermal reduction was identified as the underlying mechanism for the enhancement of the conductivity after laser irradiation on the GO film. Oxidative burning can be controlled by varying the film thickness and laser power. |
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