Figure 2. Operating principle for 2D-EFET.

(a) Strain (S) versus electric field (ξ_e) characteristics of an electrostrictive material (PMN-PT). (b) Bandgap (E_G) versus out-of-plane stress (P) characteristics of a 2D material (MoS₂). (c) Equivalent capacitive network for a 2D-EFET. (d) Schematic showing the band movement in 2D-EFET in response to applied gate bias (V_GS). Ψ_S is the usual electrostatic component, whereas Ψ_E is the electrostrictive component. Ψ_E arises due to the reduction in the bandgap of the 2D material in response to the out-of-plane stress transduced by the electrostrictive material. This gives rise to internal voltage amplification which is ultimately responsible for steep subthreshold swing (SS) less than 60 mV/decade in 2D-EFETs.