Tailored sliding ferroelectricity for ultrahigh fatigue resistance in stacked trilayer MoS2 crystals

Abstract

Fatigue-resistant ferroelectric materials in two-dimensional systems are crucial for next-generation electronic devices, but the relationship between stacking configurations and ferroelectric behavior remains underexplored. Here, we synthesize trilayer MoS₂ crystals with three noncentrosymmetric stacking configurations (AAA, AAB, and ABB) using a thermal gradient chemical vapor deposition strategy. Notable variations in room-temperature ferroelectricity are observed, with polarization strength following the order AAA > AAB > ABB, up to 0.110 microcoulombs per square centimeter. The total stress time for AAA, AAB, and ABB configurations is 10⁶ seconds under a 10-microsecond pulse width. We also identify an oscillatory feature between stacking configurations and ferroelectric polarization in multilayer systems. This work establishes a distinctive paradigm for designing robust, high-performance ferroelectric materials, unlocking scalable solutions for next-generation memory and electronic applications.

Fig. 1.. Sliding ferroelectricity mechanism and stacking configurations of trilayer MoS₂.

(A) Illustration of the sliding ferroelectricity process in trilayer MoS₂. The system transitions from the fresh state, with a downward interlayer polarization (−P), to the final state, where the interlayer polarization reverses to upward (+P) due to layer sliding. Yellow and pink spheres represent sulfur (S) and molybdenum (Mo) atoms, respectively. (B) Schematic representation of the four possible stacking configurations of trilayer MoS₂: AAA (Rhombohedral), AAB (Rhombohedral + Bernal), ABA (Bernal), and ABB (Rhombohedral + Bernal). Each configuration exhibits distinct interlayer atomic arrangements that influence the overall polarization and ferroelectric behavior.

Fig. 2.. Structural and optical characterization of four stacking configurations in trilayer MoS₂.

(A to D) Atomic-resolution STEM-HAADF images reveal the stacking order of AAA, AAB, ABA, and ABB configurations, demonstrating distinct atomic arrangements. Scale bars, 1 nm. (E to H) SHG mapping images of the four stackings show strong signals for AAA stacking, which increase with layer number, while the other three stackings exhibit weakened signals due to mixed bilayer antiparallel domains that restore inversion symmetry. Scale bars, 10 μm. (I to L) Polarized SHG patterns confirm sixfold rotational symmetry, with variations in peak intensity among stackings, reflecting differences in the degree of inversion symmetry breaking.

Fig. 3.. Ferroelectric characterization of MoS₂-based FTJs with distinct stacking configurations.

(A) Schematic representation of the Au-MoS₂-Au FTJ device structure. (B to D) Polarization–electric voltage (P-V) hysteresis loops for the AAA, AAB, and ABB stacking configurations, illustrating robust ferroelectric switching behavior with increasing remanent polarization as the electric field is enhanced. (E) Current-voltage (I-V) characteristics of the three stacking configurations, showing prominent current peaks corresponding to polarization reversal events. (F to H) Frequency-dependent P-V loops for the AAA, AAB, and ABB configurations, revealing a reduction in hysteresis width with increasing frequency due to insufficient polarization response at higher switching rates. (I) Time-current (I-t) response, demonstrating sharp current inversion during polarization switching. (J to L) Leakage current density–electric voltage (J-V) curves for the AAA, AAB, and ABB configurations, showing classic butterfly-shaped hysteresis, further confirming the ferroelectric nature of these stacking structures.

Fig. 4.. Systematic investigation of the ferroelectric behavior and fatigue resistance of MoS₂-based FTJs with different stacking configurations.

(A) Polarization comparison at different voltages with a fixed frequency for the three stacking configurations, showing that AAA exhibits the highest remanent polarization. (B) Polarization comparison at different frequencies with a fixed voltage, highlighting the varying sensitivity of polarization to frequency across the three configurations. (C) Polarization values of different stacking configurations obtained from experimental measurements and DFT calculations. (D to F) Fatigue characteristics of the three stacking configurations, demonstrating the stability of remanent polarization over multiple cycles of voltage reversal, indicating robust fatigue resistance. The fatigue behavior was measured using dynamic hysteresis measurements (DHM), which monitor the evolution of polarization values in continuously cycled P-E loops under alternating electric fields. The blue (DHM Pr+) and purple (DHM Pr−) spheres represent the polarization values under cyclic switching of positive and negative voltages, respectively. (G) Comparison of typical ferroelectric devices in terms of thickness and fatigue cycling endurance. (H) Comparison of typical ferroelectric devices as a function of thickness and total stress time. Details of the device information and related references are listed in table S1. (I) Oscillatory ferroelectricity based on different stacking configurations with devices from different batches. The error bars are also displayed.

Fig. 5.. Ferroelectric switching pathways and energy barriers for AAA, AAB, and ABB stacking configurations.

(A to C) Visualization of the ferroelectric switching pathways for the AAA (A), AAB (B), and ABB (C) stacking configurations, obtained using the CI-NEB method. Path 3 in AAA shows the lowest energy barrier. (D to F) Energy profiles of ferroelectric switching for the AAA (D), AAB (E), and ABB (F) configurations along the respective switching pathways, with energy values reported per unit cell.