Abstract
We report that the resistance of a chemical vapor deposition (CVD) grown graphene film transferred onto an SiO 2 substrate increases to higher saturation values upon exposure to light of decreasing wavelength from the visible to ultraviolet. Light in the visible range causes a slight increase of up to 10% in saturation resistance. A significant increase in resistance is found starting at about 400 nm. The saturation resistance approaches up to 3 times the original resistance at 254 nm after 5 min. When the light is removed, the resistance falls to its original value with a time constant of several days. The effect is not observed for samples of CVD-grown graphene films on SiO 2 that have been heated in vacuum at 600 ℃, nor single-crystal graphene mechanically exfoliated onto SiO 2 . We attribute the effect to photo dissociation of interfacial molecules such as H 2 O adsorbed between the CVD-grown film and SiO 2 substrate at grain boundaries in the film.
Highlights
Graphene, a truly two-dimensional material with a carbon honey-comb planar structure, has attracted tremendous attention since its first realization by exfoliation in 2004 largely due to its unique electronic properties that makes it a promising candidate in generation electronic devices and sensors [1,2,3,4,5,6,7]
We report that the resistance of a chemical vapor deposition (CVD)-grown graphene film, which is transferred from deionized (DI) water to an SiO2 substrate, increases as the wavelength of light incident on the film decreases from the visible to ultraviolet (UV)
We have observed that the resistance of CVD-grown graphene films transferred onto SiO2 substrates increases as the wavelength of incident light decreases from the visible to UV
Summary
A truly two-dimensional material with a carbon honey-comb planar structure, has attracted tremendous attention since its first realization by exfoliation in 2004 largely due to its unique electronic properties that makes it a promising candidate in generation electronic devices and sensors [1,2,3,4,5,6,7]. We report that the resistance of a CVD-grown graphene film, which is transferred from deionized (DI) water to an SiO2 substrate, increases as the wavelength of light incident on the film decreases from the visible to ultraviolet (UV). We attribute this phenomenon to photo dissociation of adsorbates such as H2O between the graphene film and SiO2 substrate that are adsorbed at grain boundaries in the film. Our results may provide a convenient method for tuning the resistivity of CVD-grown graphene films by varying the wavelength of incident light, and sensing the presence of interfacial adsorbates at grain boundaries and other defects
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