Abstract
Intriguing “slidetronics” has been reported in van der Waals (vdW) layered non-centrosymmetric materials and newly-emerging artificially-tuned twisted moiré superlattices, but correlative experiments that spatially track the interlayer sliding dynamics at atomic-level remain elusive. Here, we address the decisive challenge to in-situ trace the atomic-level interlayer sliding and the induced polarization reversal in vdW-layered yttrium-doped γ-InSe, step by step and atom by atom. We directly observe the real-time interlayer sliding by a 1/3-unit cell along the armchair direction, corresponding to vertical polarization reversal. The sliding driven only by low energetic electron-beam illumination suggests rather low switching barriers. Additionally, we propose a new sliding mechanism that supports the observed reversal pathway, i.e., two bilayer units slide towards each other simultaneously. Our insights into the polarization reversal via the atomic-scale interlayer sliding provide a momentous initial progress for the ongoing and future research on sliding ferroelectrics towards non-volatile storages or ferroelectric field-effect transistors.
Similar content being viewed by others
Introduction
In the big data era, the demand for data processing and storage manifests a booming growth. Novel in-memory computing nanodevices based on ferroelectric field-effect transistors that successfully combine ferroelectricity and semiconductor’s properties hold great potential to overcome the data traffic bottleneck relying on the von Neuman frame. Such devices require simultaneous optimizations of high ferroelectric polarizations with low switching energy barriers, moderate bandgaps with high mobility, etc1.In recent years, the intriguing sliding ferroelectricity with low barriers has been widely and solely discovered in two-dimensional (2D) materials2,3,4,5,6,whose out-of-plane (OOP) polarization reversal originates from the in-plane interlayer sliding1,3,7,8,9,10.It expands the 2D ferroelectrics from the few polar candidates to most known 2D materials that have suitable bandgaps and high mobility, including the high-performance semiconductors like MoS211,InSe12,and GaSe13.Recently, sliding induced multiple polarization states manipulation in multi-layered 2D sliding ferroelectrics2,11,14makes them promising systems for neuro-inspired computing applications. Hence, understanding the sliding mechanism is of fundamental importance to promote the researches on the sliding-related physics and the applications of slidetronics with high-speed and low-consumption. So far, many breakthroughs have been achieved not only on the constructions of twisted moiré superlattices showing sliding ferroelectricity8,9,15but also on the polarization reversal dynamics based on theoretical predictions11,16,17.Especially, the twisted lattice induced antiferroelectric moiré domains alternative changing behavior (indirect phenomena related to the domain wall motion) has been observed at micrometer-scale through electron microscopy or atomic force microscopy (AFM) including (Kelvin) piezo-force microscopy (K/PFM) characterizations10,18.Nonetheless, the real-time manipulation and investigation on the interlayer sliding induced polarization reversal at atomic level19are still in lack.
Although the spherical aberration corrected transmission electron microscopy (Cs-TEM) is regarded as the most straightforward approach to probe and confirm the sliding mechanism by in-situ monitoring the atomic interlayer sliding dynamics, atomic-scale in-situ observation of the interlayer sliding in 2D vdW-layered ferroelectrics remains elusive because of the mismatch between the TEM technique and the ultrathin feature of 2D layered ferroelectric structures20(Supplementary Fig.1,Supplementary Note1). On one hand, the high-resolution TEM (HRTEM) or high-angle annular dark field scanning TEM (HAADF-STEM) requires the focused ion beam (FIB)-prepared cross-sectional lamella to have a relatively flat and even area with a specific zone axis (Supplementary Fig.1h). On the other hand, most 2D vdW-layered sliding ferroelectrics are atomic-scale few-layered systems with relatively low stiffness, making it a prohibitive challenge to obtain a suitable lamella for atomic imaging analyses. In other words, direct observation of the interlayer directional sliding dynamics prerequires thicker or three-dimensional vdW-based materials or structures (Supplementary Fig.1h), because the real-time in-plane interlayer sliding at atomic-scale under the OOP electrical field can only be directly observed from the cross-section profile of the 2D layered specimen. Therefore, it is intrinsically distinguished from the reported plane-view observation of the moiré patterns in bi- or few-layered twisted structures, and also different from the already succeeded cases in conventional ferroelectric materials with evident phase changes or domain formation/motion at microscale21,22,23,24,25,26.Recently, the robust ferroelectricity in γ-InSe semiconductor was activated by yttrium-doping (InSe:Y) from few-layer to bulk with an adjustable bandgap around 1.2 eV and a distinguished mobility of 2000 cm2/V · s12.This vdW semiconductor with a long-thickness-ordered ferroelectricity provides a substantial platform for exploring the interlayer sliding behavior and resulted polarization inversion mechanism by the Cs-TEM technique.
Here, by utilizing the atomic-scale in-situ biasing Cs-TEM, we directly observe the reversible “ripplocation” domain walls1,27formation/motion and the external electric field induced layer stacking change in vdW-layered ferroelectric InSe:Y semiconductor. Our in-situ investigations combining with conductive atomic force microscopy (C-AFM) results demonstrate a stepwise ferroelectric response related to multiple polarization states transition. Furthermore, the kinetics of atomic-scale interlayer sliding in InSe:Y is clearly observed under the electron-beam (e-beam) illumination in STEM, which induces local electrostatic charging and local electric field21,25for polarization switching in ferroelectrics26,28,29.Such sliding is observed excluding the possible influence from the electrode, further confirming the OOP polarization switching dynamics. Additionally, first-principles calculations provide an interpretation of the role of doped-Y for observing sliding dynamics, and more importantly, validate the observed preferred reversal pathway of the simultaneous relative sliding of bilayers as blocks in InSe:Y with a sliding barrier of ~31.0 meV/f.u.
Results
The role of Y-doping in the ferroelectricity in γ-InSe
Rhombohedral γ-InSe (lattice parametersa = b = 4.00 Å andc = 25.32 Å) belongs to the C53 v(R3m) non-centrosymmetric space group with ABC-style stacking, possessing three armchair (AC) and three zigzag (ZZ) directions (Fig.1a,upper). This specified symmetry-broken atom-arrangement, which can be characterized by the second-harmonic generation (Supplementary Fig.2), illustrates the OOP polarization due to the vertical interlayer dipole moment between the bottom In atoms in one layer and the Se atoms in the adjacent layer (Fig.1a,lower)30.It has also been theoretically predicted to possess sliding ferroelectricity6,15if a vertical electric field can induce the interlayer sliding along the AC direction to reach the opposite polarization state (Fig.1b). However, due to the abundant natural stacking faults31,it is hard to detect the ferroelectricity in intrinsic γ-InSe. As a breakthrough, the trace Y-doping magically eliminates the stacking faults12and subsequently enhances the net polarization in γ-InSe (i.e., InSe:Y). Our first-principles simulations confirm that the sliding along AC direction has lower barrier than other directions. Simulations also reveal that the doped Y occupying the interstitial site (Supplementary Note2) in the vdW-gap (Yias an interlayer bridge; Fig.1c) is energetically the most probable to form in γ-InSe due to the lowest formation energy, as compared to that of substituting Se (YSe) or In (YIn), under both In-rich and Se-rich conditions (Fig.1d,red lines). The role of these Y-interstitial defects is in two-fold. On one hand, Yican restrain the random interlayer sliding to reduce the stacking faults and stabilize the crystal structure at ambient temperature by significantly increasing the interlayer sliding barrier (Fig.1e and Supplementary Note3), well agreeing with the higher hardness observed after Y-doping12.On the other hand, the structural distortions induced by the Y-interstitial defects also lead to significant increase in the polarization (from 0.096 μC/cm2to 0.931 μC/cm2;Supplementary table1), making the polarization more experimentally detectable. Subsequently, the robust ferroelectricity can be stabilized and observed experimentally, as representatively shown in the standard amplitude and phase hypothesis loops from PFM ( “Methods”, Fig.1f,Supplementary Figs.4–6,Supplementary Note5), from which we find an evident negative thickness evolution of the OOP effective-d33piezoelectric constant (deff33) with a saturation maximum value of∼14.0 pm/V (Supplementary Fig.4).
In-situ biasing-triggered interlayer sliding, ripplocation formation/motion and resulted polarization switching
We monitor the potential layer stacking changes at atomic-scale by tracing the interlayer sliding from the FIB-prepared InSe:Y cross-section specimen using the in-situ biasing Cs-TEM system (Fig.2aand Supplementary Fig.7a), where the specimen is adhered to the top of a copper gird (as the bottom electrode). The probe is a mobile electrode connecting to the electric measurement system, enabling the application of the external OOP electric field and the simultaneous observation of the interlayer sliding. The upper protective layer (Pt layer) in the FIB-prepared lamella is retained as the electrode for probe contact and the area for observation is in a certain distance away from the contact point to avoid the contact-induced strain or stress. During the bias sweeping from −8 V to 8 V, high-speed camera (25 frames/s) is used to record the evolution of the microstructure of InSe:Y at atomic level. The representative HRTEM snapshots (Fig.2b) and the corresponding fast Fourier transform (FFT) patterns (Fig.2b,inset, Supplementary Fig.8) illustrate clear stacking changes including the obvious ripplocations and the layer-sliding after applying the voltage (e.g., at ±8 V). A rather flat layer arrangement is observed if the bias is low or off (e.g., at ±0.5 V; also see the pristine structure of InSe:Y in Fig.3a), demonstrating the possible electric-field-dependent reversible structure changes. This phenomenon repeats as we periodically sweep the bias voltages (clearer in Supplementary Movies1and2). Therefore, the ripplocation formation and motion1,20,27are mainly dependent upon the bias, and it may be caused by the interlayer sliding and therefore probably involve the real-time ferroelectric polarization switching, as shown in bias-dependent PFM loops (Fig.1f). Interestingly, the new diffraction patterns (marked by arrows in Fig.2b,insets; Supplementary Fig.8) emerge at higher biases of ±4 V and ±8 V, indicating the polarization switching of InSe:Y as simulated in Supplementary Fig.9and depicted in Supplementary Note6.
Furthermore, the I-V curves during in situ TEM observation are recorded exhibiting repeatable loops with bias sweeping (Supplementary Fig.10), on which a transition of the current occurs at the corresponding voltage possibly due to the polarization switching, also suggesting the possible connection of the external electric field induced microstructural changes in InSe:Y. Moreover, we perform C-AFM probe measurement (Methods; Fig.2c) to examine the fine feature of I-V curve and confirm the current and resistance character in InSe:Y, which demonstrates distinctive hysteresis features that are characteristic of obvious resistance changes during forward/reverse voltage sweeping (Fig.2d). The measured current and associated resistance show obvious jumps with voltage increasing (Fig.2e). The stepwise feature of resistance indicates that there are multiple polarization states2,11,14during polarization reversal in InSe:Y (Fig.2f). These results provide solid evidences to confirm the link between the polarization reversal and the microstructural changes.
Limited by the influence of zone axis variations, it is difficult to get the clear HAADF atomic images during the in-situ biasing process. Therefore, in the repeated biasing circle, we randomly withdrew the probe and carried out atomic imaging analyses to examine the atomic configuration of the instantaneous state at HAADF-STEM mode. As shown in Fig.3,we can distinguish the difference of the crystal structures peculiar to electric field induced different states. As compared to the pristine state (zero-bias) of InSe:Y showing a clear and neat arrangement of the atomic layers (Fig.3a), atomic-scale ripplocations are observed after applying the bias (Fig.3b). Notice that the potential twist in the layer interface can be neglected by referring to the highly-contrasted atomic imaging in each single layer. We explicitly measure the distance change of the interlayer spacing due to the ripplocations, showing an average value of ~36 pm (varying within 20 pm~50 pm), which is comparable to the reported value shown previously in transition metal dichalcogenides both theoretically and experimentally27.Such variation of interlayer spacing further confirms the ripplocation features (Supplementary Note7).
Additionally, from the selected area electron diffraction (SAED) analyses, only one set of SAED pattern can be observed in the pristine γ-InSe:Y specimen (Fig.3c,upper), but two sets of SAED patterns appear after in-situ biasing, implying bias-induced reversed structural polarization (Fig.3c,lower; Supplementary Note6). Detailed reduced FFT analyses for the HAADF images demonstrate same FFT patterns for randomly selected regions of the pristine specimen (Supplementary Fig.11a–c), but different FFT patterns for those of the after-biasing specimen (Supplementary Fig.11d–i), suggesting the existence of multiple polarization states induced by the external electric field. The multiple polarization status of InSe:Y is clearly shown in HAADF images by the polarization directions (Fig.3d), as well as in the zoom-in HAADF images (Fig.3e, f,upper) from Fig.3dand the simulated ones (Fig.3e, f, lower) that illustrate two unit-cells of γ-InSe with totally reversed layer stacking and polarization states. These results also imply that sliding-induced multiple polarization states can be modulated in multilayer 3 RInSe by external biasing, as reported and mentioned above in the ladder ferroelectricity2and multiple polarization states of other sliding systems11,14,showing exciting promise in the multi-level storage.
Atomic-level polarization switching dynamics under e-beam illumination
We should point out that (i) the interlayer sliding barrier in 2D vdW ferroelectric systems is theoretically low (Supplementary Table2), e.g., ~0.15 meV/f.u. for bilayer WTe217and ~7.5 meV/f.u. for bilayer 3 R MoS2with thickness-dependence11;and (ii) during the Cs-(S)TEM measurements, besides the applied external electric field, the e-beam illumination also induces an electric field in nanoscale23,24,25,28,29,32,whose intensity depends on the e-beam injection dose21,29.It has been employed to flip the ferroelectric polarization in many ferroelectric materials including the hexagonal YMnO321and the newly-emerging wurtzite ferroelectrics26.Therefore, we carry out atomic-imaging on our InSe:Y samples only under the tunable e-beam illumination conditions without the probe and any external field (Fig.4a). We clearly observe the interlayer sliding between adjacent layers driven by the weak e-beam-induced electric field. As shown in Fig.4b, eand Supplementary Fig.12,compared to the state I, this field makes the mainly-focused adjacent single layer or two layers slide along the AC direction (i.e., a fast interlayer sliding dynamic) by a 1/3 in-plane unit cell (Fig.4bi,ci). This can be well rationalized in the overlapped images (Fig.4bii,cii) and the intensity line profiles (Fig.4biv,civ) of the states I and II involving the interlayer slide, which exactly leads to the opposite polarization (up and down vertically; confirmed by the atomic simulation results in Fig.4biii,ciii) (also see Fig.1b). This e-beam induced sliding behavior also provides evidence for the extra low sliding barriers between layers as predicted theoretically (Fig.1e). The observations of one layer or two layers interlayer sliding-induced polarization switching pave the way for the potential application in ultrathin (from bulk to bi-/few-layered InSe) non-volatile memories.
Furthermore, first-principles calculations are employed to investigate the sliding-induced polarization reversal pathways along AC direction and the corresponding polarization (Supplementary Note2). Based on the crystal structure of γ-InSe, or ABC-stacking in a unit cell, the sliding of two adjacent layers can intuitively lead to the polarization reversal (Supplementary Note4), e.g., ABC to ACB (or path 1 in Fig.4d,upper). The energy barrier for this path is calculated as 37.2 meV per formula unit (f.u.) (Fig.4e). However, quite a few AC-stacking structures (or ε-InSe)33are experimentally observed (Supplementary Fig.13), which cannot be explained based on path 1. Instead, a two-step path with four layers moving together at each step is proposed (path 2 in Fig.4d,lower). In the first step, four layers form two sliding units (marked by dashed rectangles) and they slide toward each other, making ABCABC stacking shift to ACACAC stacking (or ε-InSe), whereas new sliding units form in the second step and their toward-sliding makes ACACAC stacking shift to ACBACB stacking, resulting in the polarization reversal. The energy barriers of the two steps in path 2 are calculated to be ~24.1 meV/f.u., ~34% lower than the barrier of path 1, meaning path 2 has a higher probability to happen. Importantly, this new mechanism not only perfectly explains the existence of ε-InSe in γ-InSe, but also gets directly observed by in-situ STEM (Supplementary Fig.13). For both proposed paths in 3-layer or 6-layer unit cells, the interlayer shift is limited to the long-path sliding (Supplementary Notes3and4).
For the real case with a Y interstitial (concentration corresponding to one Y atom in 192 InSe f.u.; Supplementary Fig.14), the energy barrier of path 2 rises to ~31.0 meV/f.u., or 29% increase, and still lower than that of path 1 for the undoped InSe (Fig.4e). These results reveal the role of the Y-doping, which not only eliminate the random interlayer sliding in pure InSe with a higher energy barrier, but also stabilize the polarization perpendicular to the InSe:Y layers for a longer range. Combined with the predicted significant increase in OOP polarization, the robust ferroelectricity can be observed experimentally.
Along the sliding path, the OOP polarization exhibits a non-monotonic behavior, i.e., increase first, decrease to zero, and then flip to the opposite direction, whereas in-plane polarization only fluctuates without reversing its direction (Supplementary Fig.15). We also evaluate the coupling between the in-plane polarization with the applied electric field in our experiment, and find that the coupling is at most two orders of magnitude lower than the sliding energy barrier, indicating that the influence of in-plane polarization on the OOP polarization reversal is negligible.
Discussion
In summary, we directly visualize the in-situ interlayer sliding-induced polarization switching in vdW-layered sliding ferroelectric InSe:Y driven by either the external electric field or only the e-beam illumination of the (S)TEM system. The polarization reversal pathway prefers to the simultaneous relative sliding of two adjacent bilayers, consistent with the prediction from first-principles calculations. The sliding-induced stable and robust ferroelectric InSe:Y gives an extrapolated-saturateddeff33-value of∼14.0 pm/V, orders of magnitude higher than other 2D vdW few-layer structures, e.g., ~0.17 pm/V for monolayer α-In2Se334and ~1.00 pm/V for bilayer 3R-like or 2H-like MoS2/WS210.We also reveal the striking role that the slightly doped Y plays in the observation of sliding dynamics. Y-doping creates Yiin the vdW-gap, which not only optimizes the sliding barrier and enhance the even stability of layers, leading to the significant decrease of the natural stacking faults in super-flexible undoped InSe, but also raises the OOP polarization by one order of magnitude. Our results shed light on the sliding dynamics of the sliding ferroelectricity in 2D vdW-layered structures and verify the existence of multi-level polarization states in this material system, which should revolutionize the practical applications of slidetronics from ultrathin layer to semiconductors with high-speed data processing under low energy cost.
Online content
Any methods, additional references, Nature Research reporting summaries, source data, extended data, supplementary information, acknowledgements, peer review information; details of author contributions and competing interests; and statements of data and code availability are available at xxx.
Methods
Crystal growth and flake transfer
The InSe and InSe:Y crystal growth was reported in our previous work12.InSe and InSe:Y flakes for SHG and PFM analyses were prepared by employing a scotch-tape mechanical exfoliation method. To eliminate the interface effect, multilayer graphene was introduced on the highly-doped silicon substrate before InSe:Y flakes were transferred.
PFM and electrical measurements
Dual amplitude resonance tracking (DART) mode PFM measurements were carried out on an AFM system (Asylum Research Cypher, Oxford, UK). The spring constant of 2.0 N/m for the conductive Pt-coated silicon tip was adopted with the detected AC voltage of 0.5 V and the tip-sample contact resonant frequency of ~220 kHz. In addition, domain writing was performed by using the LithoPFM mode of the Asylum Research software with reverse DC biases (Vdc = ±5 V).
C-AFM I–V curves were obtained with bias sweeping from the positive to negative voltage circle, like 0 V to +1.5 V to −1.5 V to 0 V, with a time period of 1 s.
In-situ biasing Cs-TEM
TEM samples were prepared on a dual-beam FIB system (Helios G4 UX, FEI, USA).
The atomic-scale in-situ biasing TEM analyses were performed on a Cs-TEM (JEOL Grand ARM300, Japan) with a PicoFemto double tile biasing TEM holder (ZEOTools Technology Company) at HRTEM mode. A tungsten tip was used as the mobile electrode, which was precisely controlled by a piezoelectric system. The in-situ videos were obtained using Gatan OneView camera with 4 k resolution by a speed of 25 frames/s. The in-situ video was drift-corrected and processed by using GM3 in-situ data processing. The HRTEM snapshots corresponding to different external voltages were extracted from the in-situ video and filtered to remove the high-frequency noise (Supplementary Movies1and2).
Atomic-resolution imaging measurements before and after biasing were performed on the Cs-TEM at the AC-HAADF-STEM mode. Atomic-scale polarization switching under e-beam illumination was observed with the spot size of 8 C with a probe current of 23 pA or 6 C with 30 pA.
The simulated HAADF-STEM images were performed using MacTampas software. The simulated SAED patterns were obtained using CrystalKitX software.
Detailed atomic arrangement analyses for HAADF-STEM images combined with atomic quantification were performed using the Calatom software based on custom MATLAB scripts.
DFT calculations
The first-principles were carried out using the density functional theory (DFT) as implemented in the Vienna ab initio simulation package (VASP)35,36.The Perdew–Burkes–Ernzerhof (PBE)37form of the generalized gradient approximation (GGA) to the exchange-correlation functional was adopted. The projector augmented-wave (PAW) pseudopotentials with 520 eV cutoff for the planewave basis set were used38.Optb86b-vdW form is selected to describe the vdW interaction39.A 192-atom supercell is built to calculate the Y-doped defect properties. The energy barrier for sliding was realized using the nudged elastic band (NEB) method40,41.
For defect properties, the formation energy of a defect\(\ Alpha \)in the charge state\(q\)is calculated as42,
where\({E}_{{host}}\)is the total energy of the defect-free supercell, and\(E\left(\ Alpha,q\right)\)is the energy of the supercell with a defect\(\ Alpha \)with charge state\(q\).The chemical potential of elementi,which is denoted as\({\mu }_{i}\),is calculated with reference to the energy of its elemental phase\({E}_{i}\)per atom.\({\mu }_{i}\) = 0 means that the elementiis so rich that its pure elemental phase can form.\({E}_{F}\)is the Fermi level referenced to the valance band maximum\({E}_{{VBM}}\)of the defect-free structures.\(\triangle V\)includes the electrostatic potential alignment of\({E}_{{VBM}}\)as well as the finite-size correction.
Reporting summary
Further information on research design is available in theNature Portfolio Reporting Summarylinked to this article.
Data availability
All data are available in the main text or the Supplementary Material.
Code availability
The codes used to process and analyze the data presented in this work are available from the corresponding author upon request.
Change history
23 May 2024
A Correction to this paper has been published:https://doi.org/10.1038/s41467-024-48945-3
References
Wu, M. & Li, J. Sliding ferroelectricity in 2D van der Waals materials: Related physics and future opportunities.Proc. Natl. Acad. Sci.118,50e2115703118 (2021).
Deb, S. et al. Cumulative polarization in conductive interfacial ferroelectrics.Nature612,465–469 (2022).
Vizner Stern, M. et al. Interfacial ferroelectricity by van der Waals sliding.Science372,1462–1466 (2021).
Wu, M. Two-dimensional van der Waals ferroelectrics: Scientific and technological opportunities.ACS Nano15,9229–9237 (2021).
Ding, W. et al. Prediction of intrinsic two-dimensional ferroelectrics in In2Se3and other III2-VI3van der Waals materials.Nat. Commun.8,14956 (2017).
Li, L. & Wu, M. Binary compound bilayer and multilayer with vertical polarizations: Two-dimensional ferroelectrics, multiferroics, and nanogenerators.ACS Nano11,6382–6388 (2017).
Wan, Y. et al. Room-temperature ferroelectricity in 1T’-ReS2multilayers.Phys. Rev. Lett.128,067601 (2022).
Yasuda, K., Wang, X., Watanabe, K., Taniguchi, T. & Jarillo-Herrero, P. Stacking-engineered ferroelectricity in bilayer boron nitride.Science372,1458–1462 (2021).
Zheng, Z. et al. Unconventional ferroelectricity in moire heterostructures.Nature588,71–76 (2020).
Rogee, L. et al. Ferroelectricity in untwisted heterobilayers of transition metal dichalcogenides.Science376,973–978 (2022).
Meng, P. et al. Sliding induced multiple polarization states in two-dimensional ferroelectrics.Nat. Commun.13,7696 (2022).
Sui, F. et al. Sliding ferroelectricity in van der Waals layered gamma-InSe semiconductor.Nat. Commun.14,36 (2023).
Li, W. et al. Emergence of ferroelectricity in a nonferroelectric monolayer.Nat. Commun.14,2757 (2023).
Yang, L., Ding, S., Gao, J. & Wu, M. Atypical sliding and Moiré ferroelectricity in pure multilayer graphene.Phys. Rev. Lett.131,096801 (2023).
Andersen, T. I. et al. Excitons in a reconstructed moire potential in twisted WSe2/WSe2homobilayers.Nat. Mater.20,480–487 (2021).
Xu, B., Deng, J., Ding, X., Sun, J. & Liu, J. Z. Van der Waals force-induced intralayer ferroelectric-to-antiferroelectric transition via interlayer sliding in bilayer group-IV monochalcogenides.npj Comput. Mater.8,47 (2022).
Yang, Q., Wu, M. & Li, J. Origin of two-dimensional vertical ferroelectricity in WTe2bilayer and multilayer.J. Phys. Chem. Lett.9,7160–7164 (2018).
Weston, A. et al. Interfacial ferroelectricity in marginally twisted 2D semiconductors.Nat. Nanotechnol.17,390–395 (2022).
Zhang, D., Schoenherr, P., Sharma, P. & Seidel, J. Ferroelectric order in van der Waals layered materials.Nat. Rev. Mater.8,25–40 (2022).
Ko, K. et al. Operando electron microscopy investigation of polar domain dynamics in twisted van der Waals homobilayers.Nat. Mater.22,992–998 (2023).
Chen, Z., Wang, X., Ringer, S. P. & Liao, X. Manipulation of nanoscale domain switching using an electron beam with omnidirectional electric field distribution.Phys. Rev. Lett.117,027601 (2016).
Tao, J. et al. Reversible structure manipulation by tuning carrier concentration in metastable Cu2S.Proc. Natl. Acad. Sci.114,9832–9837 (2017).
Jiang, N. Electron beam damage in oxides: a review.Rep. Prog. Phys.79,016501 (2016).
Jiang, N. Beam damage by the induced electric field in transmission electron microscopy.Micron83,79–92 (2016).
Jiang, N. Note on in situ (scanning) transmission electron microscopy study of liquid samples.Ultramicroscopy179,81–83 (2017).
Calderon, S. T. et al. Atomic-scale polarization switching in wurtzite ferroelectrics.Science380,1034–1038 (2023).
Kushima, A., Qian, X., Zhao, P., Zhang, S. & Li, J. Ripplocations in van der Waals layers.Nano Lett.15,1302–1308 (2015).
Nutt, A. C. G., Gopalan, V. & Gupta, M. C. Domain inversion in LiNbO3using direct electron-beam writing.Appl. Phys. Lett.60,2828–2830 (1992).
Hart, J. L. et al. Electron-beam-induced ferroelectric domain behavior in the transmission electron microscope: Toward deterministic domain patterning.Phys. Rev. B94,174104 (2016).
Hopkinson, D. G. et al. Formation and healing of defects in atomically thin GaSe and InSe.ACS Nano13,5112–5123 (2019).
Wei, T. R. et al. Exceptional plasticity in the bulk single-crystalline van der Waals semiconductor InSe.Science369,542–545 (2020).
Jiang, N. Damage mechanisms in electron microscopy of insulating materials.J. Phys. D. Appl. Phys.46,305502 (2013).
Hao, Q. et al. Phase identification and strong second harmonic generation in pure ε-InSe and its alloys.Nano Lett.19,2634–2640 (2019).
Xue, F. et al. Multidirection piezoelectricity in mono- and multilayered hexagonal α-In2Se3.ACS Nano12,4976–4983 (2018).
Kresse, G. & Furthmuller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set.Phys. Rev. B54,11169–11186 (1996).
Kresse, G. & Furthmuller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set.Comput. Mater. Sci.6,15–50 (1996).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple.Phys. Rev. Lett.77,3865–3868 (1996).
Blochl, P. E. Projector augmented-wave method.Phys. Rev. B50,17953–17979 (1994).
Klimes, J., Bowler, D. R. & Michaelides, A. Van der Waals density functionals applied to solids.Phys. Rev. B83,195131 (2011).
Henkelman, G. & Jonsson, H. Improved tangent estimate in the nudged elastic band method for finding minimum energy paths and saddle points.J. Chem. Phys.113,9978–9985 (2000).
Henkelman, G., Uberuaga, B. P. & Jonsson, H. A climbing image nudged elastic band method for finding saddle points and minimum energy paths.J. Chem. Phys.113,9901–9904 (2000).
Wei, S. H. Overcoming the doping bottleneck in semiconductors.Comput. Mater. Sci.30,337–348 (2004).
Acknowledgements
This work was financially supported by the National Key Research Project of China grant 2022YFA1402902 (CGD), the National Natural Science Foundation of China (NSFC) grants 12134003 (CGD), 62274061 (FYY) and 61974042 (RH), the Natural Science Foundation of Chongqing, China grants CCSTB2023NSCQ-MSX0975 (RJQ) and the Fundamental Research Funds for the Central Universities grant YBNLTS2013-019 (FRS). M.J. acknowledges the ‘Shuguang Program’ supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission. M.J. and X.L. acknowledges project supported by the Space Application System of China Manned Space Program.
Author information
Authors and Affiliations
Contributions
R.Q. and F.Y. formulated and supervised the project. M.J., X.L. and F.S. prepared the samples. F.S., R.Q., B.L., R.G., Y.Z. and R.H. conducted the TEM investigations and characterizations. Y.W. Z.L. and H.L. performed the DFT calculations. F.S., R.Q., F.Y., M.W. and C.D. analyzed the data. F.Y. and R.Q. drafted the original manuscript. J.M., X.L., M.W., J.C. and C.D. reviewed and edited the manuscript with contributions from all authors.
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing interests.
Peer review
Peer review information
Nature Communicationsthanks Wei Cao and the other anonymous reviewer(s) for their contribution to the peer review of this work. A peer review file is available.
Additional information
Publisher’s noteSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visithttp://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Sui, F., Li, H., Qi, R.et al.Atomic-level polarization reversal in sliding ferroelectric semiconductors. Nat Commun15,3799 (2024). https://doi.org/10.1038/s41467-024-48218-z
Received:
Accepted:
Published:
DOI:https://doi.org/10.1038/s41467-024-48218-z