Fig. 3. Memory characteristics of the LG-FeFET.
a The device used to compare the memory properties by the lateral and vertical gates. b Double-sweep Id–Vg transfer curves using the vertical and c lateral gates. d Comparison of memory windows between the vertical and lateral gates as a function of the sweep range and e the electric field across the ferroelectric layer. f Correlation chart showing the relationship between the lateral and vertical directional electric fields within the same memory window. The bar chart shows the ratio of the vertical and lateral electric fields. g and h are conceptual energy diagrams that explain the difference of memory windows and the magnitude of the electric field. The energy diagrams are based on the Landau-Devonshire theory and first-principle density functional theory calculation, with respect to g the OOP and h the IP directional electric fields34, 66.