Figure 5.

Simplified band diagrams of the graphene-base heterojunction transistor during (a) equilibrium (BC ideal barrier shown as a dashed line). Band diagram at $V_{BE}$ = 0 V for (b) 0 V < $V_{CE}$ < 0.15 V and (c) $V_{CE}$ > 0.15 $\mathrm{V}$, and at $V_{BE}$ ≠ 0 V for (d) $V_{CE}$> 0.15 $\mathrm{V}$. The green arrows indicate the flow of electrons.