Full text loading...
(a) Device structure. A gate voltage Vgs is applied between graphene and the p++ Si substrate with the aluminum top contact grounded. (b) Representative Raman spectrum collected on our device. The ratio of the G and G’ peaks confirms that it is monolayer graphene. (c) and (d) Optical and corresponding Raman mapping image of the G peak intensity near the edge of the device. The contrast in (d) identifies the region with and without graphene which is invisible in the optical image.
(a) Photocurrent as a function of incident photon energy and gate bias. (b) Photocurrent as a function of gate voltage. (c) Cubic root of yield for negative current under different gate voltages. (d) Schottky plot of negative current (electron injection). The barrier height linearly relates to . The measurement system description and data analysis are discussed in Ref. 15
Calculated voltage drop across the oxide (red) and the difference between graphene Fermi level and its Dirac point (blue) as a function of gate voltage Vgs . The carrier concentration in graphene (green) where negative and positive values, respectively, relates to hole and electron as majority carriers. The inset shows the Id – Vgs characteristic of the device. Minimum conductivity is reached at Vgs = 0.84 V.
Band diagrams when (a) Vgs = Vfb and (b) Vgs = 0 V. All the numbers labeled in the figure are in units of eV.
Article metrics loading...