Chemistry Reference
In-Depth Information
Fig. 2. (a) Green data image of graphene films containing various number of layers.
(b) Number of pixels in the dotted frame in (a) was plotted as a dotted line with respect to
the detected green intensity (b). The inset shows the Green intensity plot depending on
the number of layers of the graphene film. Another example of a film from the red frame
in (c) is shown as a red line. These two films are directly compared after normalization
with respect to the green intensity of the substrate, as shown in (d). Here, the absolute
intensity was slightly changed when the image was slightly defocused, or the optical light
intensity was changed. However, the interval of the normalized green intensity is always
nearly constant. This method can recognize 1 to 6 layers as discrete intensity peaks.
2.2.
Device fabrication process
Graphene films cleaved from Madagascar natural graphite are fabricated
into field effect transistor. Source and drain electrodes (50-nm-thick Au
with 5-nm-thick Ti) are fabricated by electron-beam lithography and
thermal evaporation of the metals. The electrodes show ohmic contact
with the graphene with a typical resistance of less than a few kΩ.
Subsequently, a 30-nm-thick aluminum film is directly deposited
