Field-Assisted and Thermionic Contributions to Conductance in SnO_𝟐 Thick-Films

Figure 5

𝑅<Λ, the potential is not zero at the centre of the grain. The potential barrier that electrons have to cross is Δ𝐸<𝑒𝑉^′_𝑠. 𝑉^′_𝑠 is the distance between the conduction band at surface and the Fermi level; it holds 𝑉^′_𝑠<𝑉_𝑠 [13].