Intrinsic Dipole Coupling in 2D van der Waals Ferroelectrics for Gate‐Controlled Switchable Rectifier

Abstract

OOP) and in-plane (IP) ferroelectricity could be easily achieved in some atomically thin vdWs 2D ferroelectric films, such as SnTe, CuInP 2 S 6 , LiAlTe 2 , and In 2 Se 3 . [8][9][10][11][12][13][14] Particularly, different from ultrathin SnTe and CuInP 2 S 6 , whose polarization only involves either pure IP or OOP orientations, atomically thin 2D In 2 Se 3 shows both IP and OOP ferroelectricity in its ground state of the α phase. [12] And the IP and OOP polarizations of 2D α-In 2 Se 3 have strong interrelated coupling. [15][16][17][18] In the previous work, we found that the OOP dipole in trilayer In 2 Se 3 is locked by the IP lattice asymmetry and its switching is related to the inversion of IP lattice orientation. [18] Up to date, there are few reports in the literature regarding ultimate miniature switchable rectifiers made of these atomically thin 2D ferroelectrics by utilizing the dipole polarization coupling. [19] Here, we report the fabrication of a gate-controlled switchable ferroelectric diode based on the single crystal of α-In 2 Se 3 by utilizing the interrelated coupling effect of OOP and IP polarizations (Figure 1). This ferroelectric diode can be inversed effectively by switching the gate bias between the negative (Figure 1a) and the positive configurations (Figure 1b). With a good rectification property of the ferroelectric diode, a switchable dynamic half-wave rectifier was realized. This kind of 2D ferroelectric diode has the advantages of simplicity in fabrication compatibility with complementary Miniaturization of device elements, such as ferroelectric diodes, depends on the downscaling of ferroelectric film, which is also crucial for developing high-density information storage technologies of ferroelectric random access memories (FeRAMs). Recently emerged ferroelectric two-dimensional (2D) van der Waals (vdWs) layered materials bring an additional opportunity to further increase the density of FeRAMs. A lateral, switchable rectifier is designed and fabricated based on atomically thin 2D α-In 2 Se 3 ferroelectric diodes, thus breaking the thickness limitation of conventional ferroelectric films and achieving an unprecedented level of miniaturization. This is realized through the interrelated coupling between out-of-plane and in-plane dipoles at room temperature; that is, horizontal polarization reversal can be effectively controlled through a vertical electric field. Being further explored as a switchable rectifier, the obtained maximum value of rectification ratio for the α-In 2 Se 3 based ferroelectric diode can reach up to 2.5 × 10 3 . These results indicate that 2D ferroelectric semiconductors can offer a pathway to develop next-generation multifunctional electronics. www.advelectronicmat.de metal-oxide-semiconductor (CMOS) technology, and superior electrical rectifying characteristics, showing great potential for future integrated electronic applications.

Review on Recent Developments in 2D Ferroelectrics: Theories and Applications

“…In addition to the Fe-FETs and FTJs, many other useful nanodevices based on the ferroelectric-modulated electron properties are proposed, such as nanorectifiers [97] and nanomemristors. [98]…”

Intrinsic polarization coupling in 2D α‐In2Se3toward artificial synapse with multimode operations

“…Figure 2E displays the variations of the clockwise hysteresis window of transfer curves according to the different V bg sweeping range at fixed V sd = 0.2 V. It can be observed that the hysteresis window increases as the maximum V bg increases from 5 to 50 V due to the enhanced IP dipole alignment under large V bg values. 30,[43][44][45] The hysteresis behaviors under both V sd and V bg scans, as discussed above, can provide the potential for this α-In 2 Se 3 device to emulate the synaptic plasticity. To evaluate the essential synaptic behaviors, the device was first measured under V sd pulse (at V g = 0 V), as displayed in Figure 3.…”

“…It is worth noting that 100 reversible HRS–LRS switching cycles under the pulse voltage mode can be realized, as shown in Figure S6B, implying good endurance of the device. Figure 2E displays the variations of the clockwise hysteresis window of transfer curves according to the different V bg sweeping range at fixed V sd = 0.2 V. It can be observed that the hysteresis window increases as the maximum V bg increases from 5 to 50 V due to the enhanced IP dipole alignment under large V bg values 30,43–45 …”

Intertwined ferroelectricity and topological state in two-dimensional multilayer

“…directions, which leads to a zero net IP polarization. When introducing the substrate effect, the threefold rotation symmetry is broken to realize the IP ferroelectricity, which has been well demonstrated in experiment [34,[42][43][44]. Accordingly, both IP and OOP ferroelectricity can be realized in trilayer Bi2Te3.…”