Figure 4: Conductance of a suspended p–n graphene device.
(a) Two-terminal differential conductance G=dI/dV as a function of Vright and Vleft at T=1.5 K, demonstrating independent control of carrier type and density in the left and the right side of the graphene sheet. Labels in each of the four conduction regimes indicate the carrier type. (b) Conductance as a function of charge carrier density n along the dashed white line of a. (c) Zoom into the transconductance map presented, in d, around the charge neutrality point. (d) Transconductance obtained from the numerical derivative with respect to Vright of a emphasizing conductance oscillations. Colour-coded lines link the observed conductance oscillations with the FP interference pattern expected from the simple picture of Fig. 2: light-blue lines in the unipolar regime, green and blue lines for interferences on either side of the graphene in the bipolar case and orange lines for full-length interference in the bipolar regime.
