Ferroelectric semiconductor junctions based on graphene/In₂Se₃/graphene van der Waals heterostructures

Abstract

The miniaturization of ferroelectric devices offers prospects for non-volatile memories, low-power electrical switches and emerging technologies beyond existing Si-based integrated circuits. An emerging class of ferroelectrics is based on van der Waals (vdW) two-dimensional materials with potential for nano-ferroelectrics. Here, we report on ferroelectric semiconductor junctions (FSJs) in which the ferroelectric vdW semiconductor α-In 2 Se 3 is embedded between two single-layer graphene electrodes. In these two-terminal devices, the ferroelectric polarization of the nanometre-thick In 2 Se 3 layer modulates the transmission of electrons across the graphene/In 2 Se 3 interface, leading to memristive effects that are controlled by applied voltages and/or by light. The underlying mechanisms of conduction are examined over a range of temperatures and under light excitation revealing thermionic injection, tunnelling and trap-assisted transport. These findings are relevant to future developments of FSJs whose geometry is well suited to miniaturization and low-power electronics, offering opportunities to expand functionalities of ferroelectrics by design of the vdW heterostructure.

Tunable Band Alignments in 2D Ferroelectric α-In2Se3 Based Van der Waals Heterostructures

“…A number of theoretical designs have been proposed recently to use 2D ferroelectric materials as a functional substrate to tune the electronic, − optical, , and magnetic − properties of adlayers or the whole heterostructures. Novel 2D ferroelectric-based devices have also been increasingly demonstrated experimentally. − A conceivable mechanism of tuning is related to the feature of polarization dependent band alignment in ferroelectric-based vdW heterostructures. Due to the presence of the out-of-plane polarization, there exists a built-in electric field in the ferroelectric layer, and this leads to different alignments of its energy bands with respect to the vacuum levels of the different surfaces of the ferroelectric layer.…”

Electrostatic Coupling in MoS2/CuInP2S6 Ferroelectric vdW Heterostructures

“…Furthermore, the vdW thin flakes can be assembled on arbitrary surfaces, lifting the substrate constraint for epitaxial thin films. Although a myriad of device paradigms built on ferroelectric vdW heterojunctions, including ferroelectric field-effect transistor (FeFET), ferroelectric tunneling junction (FTJ), and negative capacitance FET, have sprung up in the past few years, [23][24][25][26][27][28][29][30] a comprehensive insight into the electrostatic coupling at the vdW interface is still lacking. Specifically, the interactions of polarization charges, injected charges, and mobile carrier charges are strongly intertwined, obscuring the actual microscopic mechanism, which may even lead to a completely opposite interpretation of the results.…”

Ultrasensitive Ferroelectric Semiconductor Phototransistors for Photon‐Level Detection

“…α‐In 2 Se 3 was chosen because of its ferroelectricity, as evidenced by the naturally existed ferroelectric domains detected by piezoresponse force microscope (PFM, Figures S1 and S2, Supporting Information, and an appropriate bandgap of ≈1.38 eV). [ 14–21 ] Moreover, α‐In 2 Se 3 has a high light absorption ability [ 15 ] and a high on/off ratio of over 10 8 . [ 18 ]…”

“…α-In 2 Se 3 was chosen because of its ferroelectricity, as evidenced by the naturally existed ferroelectric domains detected by piezoresponse force microscope (PFM, Figures S1 and S2, Supporting Information, and an appropriate bandgap of ≈1.38 eV). [14][15][16][17][18][19][20][21] Moreover, α-In 2 Se 3 has a high light absorption ability [15] and a high on/off ratio of over 10 8 . [18] Coupling between ferroelectric and semiconducting properties of α-In 2 Se 3 lays the foundation for the ultra-sensitive photodetection, which is firstly verified through a V GS pulse test.…”