For neuromorphic computing, integrating multiply-accumulate operations and nonlinear activation within a single device can reduce latency and power consumption while improving computational efficiency. However, these operations impose conflicting requirements: multiply-accumulate requires highly linear and non-volatile resistance states, while activation requires diverse nonlinear synaptic behaviors. These contrasting demands make integrating both functions in a single device challenging. Here, we construct a multimodal ion-gate transistor using 2D CdPS3-Li as dielectric layer and MoS2 as channel material. The layered structure of CdPS3-Li facilitates anisotropic ion transport for Li+ storage and produces strong ion-electron coupling, resulting in high-linearity and non-volatile resistance states under electrical pulses. Moreover, Cd vacancies in CdPS3-Li attract and trap photo-generated holes from MoS2, leading to rich nonlinear behavior under light pulses. Therefore, the CdPS3-Li transistor can simultaneously perform both operations. The CdPS3-Li transistor arrays achieved high accuracy in handwritten digit classification, offering a promising hardware solution for neuromorphic computing.

Due to the comprehensive performance of the phase-change radio-frequency (rf) switch, it provides a promising idea for the next generation of alternative microwave switch. This work reports that the directly heated phase-change switches based on GeTe/Sb superlatticelike (SLL) material have excellent switching and rf transmission performance. Compared to single-component phase-change materials, GeTe/Sb SLL systems have lower thermal conductivity. As a functional layer of switching devices, the utilization rate of Joule heat can be improved, thus improving the switching speed of the device and reducing operating energy consumption. The contact area between the electrode and the phase-change material is reduced, and the switching structure is optimized to further improve the heating efficiency. The pulse width of the rf switch operating voltage is as low as 100 ns, with a total energy consumption of 758.5 nJ. It was found that the insertion loss of the phase-change switch unit is less than 0.76 dB, and the isolation is greater than 20.8 dB (0.1-67 GHz), respectively. Moreover, single-pole double-throw (SPDT) and single-pole four-throw (SP4T) phase-change rf switches can be fabricated by controlling the configuration between switching units. The present rf switches based on GeTe/Sb SLL materials can be used in future wireless and 6G communication reconfiguration systems to switch between signal-processing modules to optimize signal quality and coverage.

GeTe is a crucial phase change material, and its phase transition under pressure remains incompletely understood. In this work, we employed the density functional theory calculations to establish the variations in GeTe induced by pressure. Three phases are identified from the bandgap, the enthalpy-pressure (H−P) profile, and the unit cell volume: the low-pressure rhombohedral phase (R3m), the intermediate-pressure cubic phase (Fm3¯m), and the high-pressure orthorhombic phase (Pnma). The R3m to Fm3¯m phase occurs at 4 GPa, and that from the Fm3¯m to Pnma phase occurs at 15 GPa. Analyzing electron localization functions and Born effective charges between Ge and Te atoms jointly revealed the bonding characteristics: The R3m and Fm3¯m phases are dominated by covalent bonds, and the Pnma phase is contributed by ionic bonds. This provides a theoretical basis at the electronic and bonding levels, supporting the device applications of GeTe in high-pressure environments.

Monolayer MoS2 is attractive for future photonics and optoelectronics for its direct-gap excitons with ultrahigh binding energies. However, the atomically thin structure is prone to nonradiative defects, challenging to scale for large-area production, and inherently limited in optical cross-section, all hindering technological integration. Stacking monolayers to increase the optical cross-section results in multilayers with diminished photoluminescence activity. Electrochemical molecular intercalation of multilayer MoS2 weakens interlayer coupling, creating a bulk monolayer material that retains monolayer characteristics within a multilayered "bulk" architecture. However, the electrochemical process often severely degrades the optical quality and is difficult to implement for scalable thin film production. Here, we report a luminescent monolayer MoS2 colloidal ink for scalable solution processing of large-area bulk monolayer MoS2 membranes with thickness-scalable bright luminescence. Using perfluorinated sulfonic-acid ionomer (Nafion) as a multifunctional ligand, we achieve a stable dispersion of monolayer MoS2 ink that can be readily processed into large-area stretchable membranes with diverse form factors. The Nafion interlayers decouple interlayer interactions while effectively passivating nonradiative defects, preserving direct-gap monolayer characteristics in thickness-scalable MoS2/Nafion membranes. This leads to unprecedented enhancements in both linear and nonlinear excitonic transitions, showing over 100-fold brighter excitonic photoluminescence and nearly 1000 times stronger second harmonic generation. These remarkable properties remain robust against intense laser irradiation, diverse environmental conditions, and mechanical deformations. Our studies overcome the longstanding challenge of poor optical quality in solution-processed monolayer MoS2 ink materials, establishing a large-area, thickness-scalable platform for excitonic devices across diverse technological domains, including photonics, optoelectronics, solution-processable bioelectronics, and electrochemical sensing.

Aluminum scandium nitride (AlScN) enables reconfigurable thin-film bulk acoustic resonators (FBARs) by combining piezoelectric and ferroelectric properties. This work explores dynamic switching of ferroelectric AlScN films by tailoring external voltage waveforms, enabling frequency control and multi-mode operation in FBAR devices. We successfully fabricated FBARs with polarity-inverted AlN/AlScN stack and demonstrated effective modulation of the frequency response through ferroelectric switching of the AlScN layer. This approach yields distinct frequency characteristics corresponding to either the fundamental TE1 or the high-order TE2 mode. This study establishes a framework for understanding AlScN ferroelectric dynamics while pioneering multi-state acoustic devices through engineered waveform control. The demonstrated non-volatile stabilization of intermediate polarization states unlocks new pathways for FBAR reconfigurability beyond conventional binary switching.

Photoinduced phase transitions (PIPTs) allow complex interactions to be distinguished within the constraints of atomic motion. Here, using real-time time-dependent density functional theory (rt-TDDFT) simulations combined with occupation-constrained density functional theory (DFT) methods, we reveal the ultrafast dynamics of ReS2 monolayer driven by photoexcitation at varying levels of electronic occupancy. The results show that the phase transition from diamond-shaped to zigzag-shaped to quasi-diamond-shaped (DS-ZS-DS') is effectively induced by 4% excitation manually, resulting in the formation of new quasidiamond chains along the direction of the original diamond chains rotated by pi /3. Notably, under pulse excitation, the entire dynamic process also includes subsequent recovery, during which the quasidiamond chains rotate back to their original direction. The phase transition is mediated by the atomic force caused by photoexcited electrons occupying the antibonding state of the Re-Re bonds between the Re4 diamonds, accompanied by the modulation of the potential energy surface. The thermal phonon vibration can effectively reduce the optical excitation fluency required to drive the bond dissociation and rearrangement. These findings provide an important guiding significance for nonequilibrium phase regulation.

Tin selenide (SnSe) is promised as a candidate for two-dimensional (2D) channels due to the abilities of high carrier mobility, high on-state current, and easy electron or hole doping. However, high-performance p-type SnSe field-effect transistors (FETs) have hardly ever been verified in the laboratory. Here, we directly synthesize SnSe nanosheets on a hexagonal boron nitride (hBN) surface and confirm the formation of a SnSe/hBN structure. According to careful identification, the growth of SnSe lattices originates from the 2 nm thickness amorphous structures, which may be the amorphous SnSe at the SnSe/hBN interface. Through excellent Au Ohmic contact, all p-type FETs made of SnSe grown on hBN achieve the field-effect mobilities above 100 cm2(Vs)-1 and the maximum of 292 cm2(Vs)-1 at room temperature, which evidently surpasses other p-type FETs with various channels. This result benefits from the high-quality SnSe channel and the special SnSe/hBN interface. Our research will enable the extension of SnSe applications in monolithic 3D integration.

GeTe has garnered significant attention in the field of phase-change memory devices due to its exceptional electrical transport properties and unique thermal response behavior. However, the temperature-induced phase transition mechanisms in large-sized GeTe single crystals remain insufficiently understood. In this work, highquality centimeter-scale GeTe single crystals were successfully synthesized. Variable-temperature X-ray diffraction shows the merging of the diffraction peaks began at 600 K. The peaks at 24.9 degrees(003) and 26.0 degrees degrees(101) gradually merge into the (111) peak at 25.7 degrees. Other peaks at 41.9 degrees(104) and 43.3 degrees(110) gradually merge into the (220) peak at 42.6 degrees. These phenomena collectively indicate GeTe's phase transition from rhombohedral to cubic phase. The change of the A2g and A3g Raman mode, indicate a structural transition of GeTe in the 600-660 K temperature range. All modes exhibit strong polarization dependence under cross-polarized configurations. Notably, the depolarization ratio serves as a quantitative indicator to accurately reveal the phase transition evolution and symmetry characteristics of GeTe. Finally, the first-principles calculations were employed to analyze the internal electronic structure changes. These calculations provided robust evidence for the superior properties of GeTe. This research contributes to a deeper understanding of temperature-driven phase transition mechanisms in large-sized GeTe single crystals.

This study utilized co-sputtering to fabricate Mo-doped VO2 films and identified an optimal concentration exhibiting a lower phase transition temperature (Th = 55.8 °C) and a broader hysteresis window (Δ T = 13.6 °C). At the atomistic scale, it is demonstrated that Mo dopant-induced localized strain accelerates the phase transition, which leads to the relaxation of the tetragonal structure. Furthermore, the effects of Mo doping on the phase transition process and electrical properties are characterized at the nanoscale using conductive atomic force microscopy and Kelvin probe force microscopy, and the potential application in selectors can be evaluated. The results indicated that Mo doping destabilizes the M1 phase by introducing a high density of electrons, thereby significantly reducing the electron–electron interactions as per the Mott model. Moreover, the device exhibited stable threshold and memristive properties at room temperature, quickly switching from high to low-resistance states at a threshold voltage of 2.37 V and maintaining stability over more than 1000 cycles with a selectivity >102. The present work not only highlights the role of Mo doping in enhancing the functional properties of VO2 but also demonstrates its feasibility in high-performance selectors devices.

With the booming development of two-dimensional (2D) flexible devices, flexure has attracted much attention as an emerging means to modulate device performances. Here, the magnetic-optical-electrical multifield coupling mechanism of spin photocurrent in bent CrSBr monolayer is investigated through first-principles calculations. The studies show that simple mechanical bending of monolayer CrSBr can successfully achieve the spatial separation of electrons and holes. The nonequilibrium process of photogenerated carriers in bent CrSBr modulates both the shift current density and the ballistic current density, thereby enabling the photovoltaic effect. Meanwhile, the built-in electric field generated by flexure drives the device toward more efficient self-powered behavior. Moreover, this self-powered polarization devices have excellent spin photovoltaic properties and high polarization sensitivity. The present Letter creates novel opportunities for 2D spintronics and opens new avenues for realizing self-powered polarization devices.

Phase change material (PCM) based information memory mainly relies on the rapid transition from amorphous and crystalline states of these systems. While extensive research has been focused on the crystallization process of PCM, physical mechanisms on the amorphization process have been limited and insufficiently explored to date. Here, we systematically investigate the amorphization dynamics and local order of tantalum (Ta)-doped Sb2Te material under thermally induced melting-quenching and photoexcitation processes, using ab initio molecular dynamics and real-time time-dependent density-functional theory methods, respectively. During the melt-quenching process, the doping of Ta atoms enhances local order by promoting the formation of high-coordination and triangular configurations, thereby improving the thermal stability of the amorphous structure. The core mechanism of the pulsed laser-induced amorphization originates from the dynamic modulation of interatomic bonding characteristics by photoexcited carriers, which can reduce the amorphization barrier and drive structural instability. Compared with the former, the latter induces the increase of tetrahedral structure and a higher number of rings in the amorphous process, while the local Peierls distortion attenuates, reducing the risk of resistance drift. This work provides insights on the amorphization dynamics of Ta-doped Sb2Te and related PCM induced by both thermal and photoexcitation.

Chalcogenide is an essential construction material for emerging nanoelectro-optical memories and radio-frequency (rf) switches, yet the latter still lacks comprehensive insights from theoretical mechanisms to device components. Here, we conceive of a directly heated chalcogenide-based phase-change rf switch with two-dimensional constrained Sb, a pivotal component of microwave switches capable of low energy consumption and ultrafast responses. In their quasi-two-dimensional amorphous counterparts, Peierls distortion is consolidated with highly localized electrons elevating the electrical resistivity of the scale-shrinking Sb that originates from quantum confinement effects, favoring low-Joule-heat energy barriers. The fabricated Sb-based phase-change rf switch operates with insertion loss of less than 1.2 dB and isolation of greater than 18 dB (up to 67 GHz). The total switch energy consumption can be as low as 1.1 mu J, with over 3 orders of magnitude switching ratio. The ultrafast recrystallization process in the dimensional limit benefits from glass homogeneity along with the topological rearrangement of the three-to fourfold rings, explaining the 300-ns ultrafast response of the rf switch regarding geometrical-physical relevance. This work provides insights into chalcogenide-based assembly for rf switches that allow for future reconfiguration of wireless and 6G communication systems.

In this work, 10 nm scandium-doped aluminum nitride (AlScN) capacitors are demonstrated for the construction of the selector-free memory array application. The 10 nm Al0.7Sc0.3N film deposited on an 8-inch silicon wafer with sputtering technology exhibits a large remnant polarization exceeding 100 µC/cm2 and a tight distribution of the coercive field, which is characterized by the positive-up-negative-down (PUND) method. As a result, the devices with lateral dimension of only 1.5 μm show a large memory window of over 250% and a low power consumption of ~40 pJ while maintaining a low disturbance rate of <2%. Additionally, the devices demonstrate stable multistate memory characteristics with a dedicated operation scheme. The back-end-of-line (BEOL)-compatible fabrication process, along with all these device performances, shows the potential of AlScN-based capacitors for the implementation of the high-density selector-free memory array.

Aluminum Scandium Nitride (Al1-xScxN) has received attention for its exceptional ferroelectric properties, whereas the fundamental mechanism determining its dynamic response and reliability remains elusive. In this work, an unreported nucleation-based polarization switching mechanism in Al0.7Sc0.3N (AlScN) is unveiled, driven by its intrinsic ferroelectricity rooted in the ionic displacement. Fast polarization switching, characterized by a remarkably low characteristic time of 0.00183 ps, is captured, and effectively simulated using a nucleation-limited switching (NLS) model, where the profound effect of defects on the nucleation and domain propagation is systematically studied. These findings are further integrated into Monte Carlo simulations to unravel the influence of the activation energy for ferroelectric switching on the distributions of switching thresholds. The long-term reliability of devices is also confirmed by time-dependent dielectric breakdown (TDDB) measurements, and the effect of thickness scaling is discussed. Ferroelectric field-effect transistors (FeFETs) are demonstrated through the integration of AlScN and 2D MoS2 channel, where biological synaptic functions can be emulated with optimized operation voltage. The artificial neural network built from AlScN-based FeFETs achieves 93.8% recognition accuracy of handwritten digits, demonstrating the potential of ferroelectric AlScN in future neuromorphic computing applications. The intrinsic ferroelectric switching characteristics of aluminum scandium nitride has been revealed and the profound effect of defects on the nucleation and domain propagation is systematically studied. The device integration of aluminum scandium nitride and 2D materials holds great potential for neuromorphic computing. image

Ferroelectric scandium-doped aluminum nitride (Al1-xScxN) is of considerable research interest because of its superior ferroelectricity. Studies indicate that Al1-xScxN may suffer from a high leakage current, which can hinder further thickness scaling and long-term reliability. In this work, we systematically investigate the origin of the leakage current in Al0.7Sc0.3N films via experiments and theoretical calculations. The results reveal that the leakage may originate from the nitrogen vacancies with positively charged states and fits well with the trap-assisted Poole-Frenkel (P-F) emission. Moreover, we examine the cycling behavior of ferroelectric Al0.7Sc0.3N-based FeRAM devices. We observe that the leakage current substantially increases when the device undergoes bipolar cycling with a pulse amplitude larger than the coercive electric field. Our analysis shows that the increased leakage current in bipolar cycling is caused by the monotonously reduced trap energy level by monitoring the direct current (DC) leakage under different temperatures and the P-F emission fitting.

2D materials have emerged as potential building blocks for electrochemical metallization (ECM) memristors with excellent performance. The evolution dynamics of conductive filaments (CFs) directly determine the resistance switching performance of the 2D material-based ECM memristors. However, achieving controllable CFs under the operation conditions remains challenging. Here, in situ transmission electron microscopy was employed to investigate the formation and evolution of CFs in Au/MoS2/Ag planar ECM memristors under electric fields, and various growth modes of CFs dependent on electric field strength were revealed. As the electric field intensity increased, the CFs exhibited diverse morphological variations, transitioning from a nanocluster-type to a continuous solid-type. Especially, the nanocluster-induced CF growth and nanobridge-assisted coalescence of nanoclusters under the electric field were observed, wherein bipolar electrochemical reactions were identified as playing a crucial role in the morphological evolution of nanoclusters and the formation of CFs. The results provide insights into the optimization of ECM planar memristors based on 2D materials.

Designing an electromagnetic wave (EMW) absorbing material with ultra-wide effective absorption bandwidth (EAB) and low filling ratio is the key to solving the problem of electromagnetic pollution. In this study, the porous Ba2Co2Mn1.2Fe10.8O22/C (Mn-Co2Y/C) composites were prepared by radial freeze-drying method as well as high temperature carbonization process (400 degrees C, 500 degrees C, 600 degrees C, and 700 degrees C). The research results indicate that the sample annealed at 600 degrees C exhibits superior EMW absorption properties, achieving the widest EAB of 5.77 GHz at a thickness of 1.7 mm, which is attributed to the synergistic effect of multiple reflections of EMWs within microchannels of the samples and the interfacial polarization between Mn-Co2Y ferrite and C material. Samples prepared at 600 degrees C have the best impedance matching, which makes it easier for EMWs to enter the material, thus exhibiting better EMW absorption performance. The magnetic loss mainly originates from natural resonance at low frequencies and eddy current loss at high frequencies, and the dielectric loss stems from relaxation loss and conductivity loss.

The study of conventional lateral memristors has been in a slow stage of development due to the dependence of the atomic defect migration or local phase transition in two-dimensional (2D) materials. Here, a novel transversal memristor based on the flexoelectric effect induced by a bent atomic laminated structure is proposed. The memristor exhibits desirable resistive switching performance, including a current ON/OFF ratio of approximately 105, forming-free operation, high yield of 97 %, and low cycle-to-cycle variation of only 7.4 %. The stable analog memristive behavior could be attributed to the dynamic modulation of the barrier between suspended and flat regions by external voltage biases. Further, the volatile resistance switching characteristics have successfully emulated key features of multi-field perceptual artificial nociceptors, including threshold, "no adaptation" etc. This work demonstrates a new resistive switching phenomenon in transversal 2D material devices, and opens a new way for the development of intelligent adaptive artificial sensory systems.

Photonic synapses combining photosensitivity and synaptic function can efficiently perceive and memorize visual information, making them crucial for the development of artificial vision systems. However, the development of high-performance photonic synapses with low power consumption and rapid optical erasing ability remains challenging. Here, we propose a photon-modulated charging/discharging mechanism for self-powered photonic synapses. The current hysteresis enables the devices based on CsPbBr 3 /solvent/carbon nitride multilayer architecture to emulate synaptic behaviors, such as excitatory postsynaptic currents, paired-pulse facilitation, and long/short-term memory. Intriguingly, the unique radiation direction-dependent photocurrent endows the photonic synapses with the capability of optical writing and rapid optical erasing. Moreover, the photonic synapses exhibit exceptional performance in contrast enhancement and noise reduction owing to the notable synaptic plasticity. In simulations based on artificial neural network (ANN) algorithms, the pre-processing by our photonic synapses improves the recognition rate of handwritten digit from 11.4% (200 training epochs) to 85% (~60 training epochs). Furthermore, due to the excellent feature extraction and memory capability, an array based on the photonic synapses can imitate facial recognition of human retina without the assistance of ANN.

Ti/Pt/Al 0.6 Sc 0.4 N/Pt capacitor structure was fabricated. Post-annealing was carried out in nitrogen atmosphere at temperature up to 800 °C to evaluate the thermal stability of the AlScN/Pt interfaces. Material characterization revealed that the AlScN (0002) and the Pt (111) textures remained stable until the annealing temperature did not exceed 500 °C. Annealing at 600 °C and above resulted in notable Pt diffused into the AlScN film, and the bottom Pt reacted with the Si substrate to form PtSi. The thermal assisted intermixing reduced the effective dielectric thickness. Lower dielectric breakdown voltage was thus recorded.