Two-dimensional (2D) materials such as semiconductors and ferroelectrics are promising for future energy-efficient logic devices because of their extraordinary electronic properties at atomic thickness. In this work, we investigated a van der Waals heterostructure composited of 2D semiconducting MoS2and 2D ferroelectric CuInP2S6(CIPS) and NiPS3. Instead of using 2D ferroelectrics as conventional gate dielectric layers, here we applied CIPS and NiPS3as a ferroelectric capping layer, and investigated a long-distance coupling effect with the gate upon the sandwiched 2D MoS2channels. Our experimental results showed an outstanding enhancement of the electrodynamic gating in 2D MoS2transistors, represented by a significant reduction of subthreshold swing at room temperature. This was due to the coupling-induced polarization of 2D ferroelectrics at 2D semiconductor surface which led to an effective and dynamic magnification of the gate capacitance. Meanwhile, the electrostatic gating was remained steady after adding the ferroelectric capping layer, providing ease and compatibility for further implementation with existing circuit and system design. Our work demonstrates the long-distance coupling effect of 2D ferroelectrics in a capping architecture, reveals its impacts from both electrodynamic and electrostatic perspectives, and expands the potential of 2D ferroelectrics to further improve the performance of energy-efficient nanoelectronics.
The research on two-dimensional (2D) van der Waals ferroelectrics has grown substantially in the last decade. These layered materials differ from conventional thin-film oxide ferroelectrics in that the surface and interface are free from dangling bonds. Some may also possess uncommon properties, such as bandgap tunability, mechanical flexibility, and high carrier mobility, which are desirable for applications in nanoelectronics and optoelectronics. This Tutorial starts by reviewing the theoretical tools in 2D ferroelectric studies, followed by discussing the material synthesis and sample characterization. Several prototypical electronic devices with innovative functionalities will be highlighted. Readers can use this article to obtain a basic understanding of the current status, challenges, and future prospects of 2D ferroelectric materials.
more » « less- Award ID(s):
- 2118806
- NSF-PAR ID:
- 10372284
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- Journal of Applied Physics
- Volume:
- 132
- Issue:
- 12
- ISSN:
- 0021-8979
- Page Range / eLocation ID:
- Article No. 121102
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Recently, the developments of two-dimensional (2D) ferroelectrics and multiferroics have attracted much more attention among researchers. These materials are useful for high-density devices for multifunctional applications such as sensors, transducers, actuators, non-volatile memories, photovoltaic, and FETs. Although several theoretical works have been reported on layered ferroelectrics, experimental work is still lacking in single to few-atomic layers of 2D ferroelectric materials. In this review, we have discussed the recent theoretical as well as experimental progress of 2D ferroelectric and multiferroic materials. The emphasis is given to the development of single to few-atomic layers of 2D ferroelectric materials. In this regard, the recent developments of 2D ferroelectric polarization on vanadium oxyhalides VOX2 (X=I, Br, Cl, and F), distorted phase d1-MoTe2, In2Se3, and SnSe are discussed. d1-MoTe2 shows Curie temperature (TC) above room temperature, while few-layered In2Se3 shows in-plane ferroelectricity and interesting domain wall dynamics in a single atomic layer of SnSe. This follows the discussion of multiferroic materials based on transition metal oxyiodide MOI2 (M=Ti, V, and Cr), double perovskite bilayer, and iron-doped In2Se3. While pristine In2Se3 shows ferroelectric properties, iron-doped In2Se3 shows multiferroicity. Finally, the potential applications of 2D ferroelectrics and multiferroics have been discussed that follow the challenges and opportunities in this field, which can guide the research community to develop next-generation 2D ferroelectric and multiferroic materials with interesting properties.more » « less
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