Fig. 2: Mechanism of FeFET Pockels photonic memory based on Pockels effect.

a–c The cross-section illustration of the FeFET Pockels photonic memory during RESET and WRITE operations. The current flowing through the IGZO channel enables non-destructive electrical readout. d–f Band diagrams along the vertical stack of the device in volatile, reset and NV optical states, respectively. The white regions represent the energy gap. In NV optical states, due to the aligned direction of HZO polarization with z-cut lithium niobate spontaneous polarization, the HZO exhibits robust retention of polarization. Since the hole carrier concentration (10¹⁴cm⁻³)⁵⁶ and hole mobility (0.01 cm²/Vs)¹² are low in the IGZO channel, the device exhibits a sub-pA off-state leakage current. Furthermore, the absence of screening carriers in the channel enables the penetration of the electric field of HZO into LN. The volatile optical state exists only during the RESET operation. After the RESET operation, the spontaneous polarization of lithium niobate tends to reverse the dipoles in HZO, resulting in a blueshift from the volatile optical state to the reset optical state. (E-field electric field, \({{P}_{0}}^{ \rightharpoonup }\): HZO polarization, \({{P}_{s}}^{ \rightharpoonup }\) LN spontaneous polarization, V_DS source-drain voltage, V_G gate voltage, E_r electric field generated by gate voltage, E_o HZO coercive field).