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. Author manuscript; available in PMC: 2020 Jan 1.
Published in final edited form as: Carbon N Y. 2019;142:10.1016/j.carbon.2018.10.085. doi: 10.1016/j.carbon.2018.10.085

Figure 2.

Figure 2.

(a) The Hall resistance for some devices are shown at 1.6 K, with all gray curves representing data after the device has been left to stabilize in air for 24 h or more, before temperatures above 300 K were applied. Each of the four panels depicts a different measurement where the device was first allowed to chemically equilibrate with air, followed by annealing in vacuum. The total IHE increases with each panel. In all cases, when the device is left in air for a period of at least one day, the device’s carrier density returns to a value on the order of 1010 cm−2. (b) When the device is warmed up to room temperature and stored in air, the longitudinal resistivity shifts and asymptotically reaches a maximum over approximately 70 hr, resulting in a Fermi level of EG that is close to the Dirac point. Two exponential decays comprise this behavior, as seen in the inset, and are then used to fit the data.