Figure 2
From: Surface effects on electronic transport of 2D chalcogenide thin films and nanostructures
Substrate effects on graphene transport. (A) STM topographic (top) and charge density (bottom) maps of graphene on SiO2. The surface is rough due to the substrate. Inhomogeneous charge density fluctuations are observed. (B) Mobility of graphene as a function of carrier density for graphene on SiO2 (dotted gray), suspended graphene before (blue) and after (red) current annealing. Current annealing of suspended graphene increases mobility as surface adsorbates desorb from graphene. (C) STM topographic (top) and charge density (bottom) maps of graphene on hBN. Unlike the STM results of graphene on SiO2, the topography shows a flat surface with Moiré patterns. Charge fluctuations are greatly reduced in the graphene/hBN case. (A, C) Reprinted with permission from Ref. 26. (B) Reprinted with permission from Ref. 29.