In these days, the increasing massive data are being produced and demanded to be processed with the rapid growth of information technology. It is difficult to rely solely on the shrinking of semiconductor devices and scale-up of the integrated circuits (ICs) again in the foreseeable future. Exploring new materials, new-principle semiconductor devices and new computing architectures is becoming an urgent topic in this field. Ambipolar two-dimensional (2D) semiconductors, possessing excellent electrostatic field controllability and flexibly modulated major charge carriers, offer a possibility to construct reconfigurable devices and enable the ICs with new functions, showing great potential in computing capacity, energy efficiency, time delay and cost. This review focuses on the recent significant advancements in reconfigurable electronic and optoelectronic devices of ambipolar 2D semiconductors, and demonstrates their potential approach towards ICs, like reconfigurable circuits and neuromorphic chips. It is expected to help readers understand the device design principle of ambipolar 2D semiconductors, and push forward exploring more new-principle devices and new-architecture computing circuits, and even their product applications.

Ferroelectric domain walls appear as sub-nanometer-thick topological interfaces separating two adjacent domains in different orientations, and can be repetitively created, erased, and moved during programming into different logic states for the nonvolatile memory under an applied electric field, providing a new paradigm for highly miniaturized low-energy electronic devices. Under some specific conditions, the charged domain walls are conducting, differing from their insulating bulk domains. In the past decade, the emergence of atomic-layer scaling solid-state electronic devices is such demonstration, resulting in the rapid rise of domain wall nano-electronics. This review aims to the latest development of ferroelectric domain-wall memories with the presence of the challenges and opportunities and the roadmap to their future commercialization.

To simplify the fabrication process and increase the versatility of neuromorphic systems, the reconfiguration concept has attracted much attention. Here, we developed a novel electrochemical VO₂ (EC-VO₂) device, which can be reconfigured as synapses or LIF neurons. The ionic dynamic doping contributed to the resistance changes of VO₂, which enables the reversible modulation of device states. The analog resistance switching and tunable LIF functions were both measured based on the same device to demonstrate the capacity of reconfiguration. Based on the reconfigurable EC-VO₂, the simulated spiking neural network model exhibited excellent performances by using low-precision weights and tunable output neurons, whose final accuracy reached 91.92%.

The discovery of ferroelectricity in HfO₂ based materials reactivated the research on ferroelectric memory. However, the complete mechanism underlying its ferroelectricity remains to be fully elucidated. In this study, we conducted a systematic study on the microstructures and ferroelectric properties of Hf_0.5Zr_0.5O₂ (HZO) thin films with various annealing rates in the rapid thermal annealing. It was observed that the HZO thin films with higher annealing rates demonstrate smaller grain size, reduced surface roughness and a higher portion of orthorhombic phase. Moreover, these films exhibited enhanced polarization values and better fatigue cycles compared to those treated with lower annealing rates. The grazing incidence x-ray diffraction measurements revealed the existence of tension stress in the HZO thin films, which was weakened with decreasing annealing rate. Our findings revealed that this internal stress, along with the stress originating from the top/bottom electrode, plays a crucial role in modulating the microstructure and ferroelectric properties of the HZO thin films. By carefully controlling the annealing rate, we could effectively regulate the tension stress within HZO thin films, thus achieving precise control over their ferroelectric properties. This work established a valuable pathway for tailoring the performance of HZO thin films for various applications.

Cold-source field-effect transistors (CS-FETs) have been developed to overcome the major challenge of power dissipation in modern integrated circuits. Cold metals suitable for n-type CS-FETs have been proposed as the ideal electrode to filter the high-energy electrons and break the thermal limit on subthreshold swing (SS). In this work, regarding the p-type CS-FETs, we propose TcX₂ and ReX₂ (X = S, Se) as the injection source to realize the sub-thermal switching for holes. First-principles calculations unveils the cold-metal characteristics of monolayer TcX₂ and ReX₂, possessing a sub-gap below the Fermi level and a decreasing DOS with energy. Quantum device simulations demonstrate that TcX₂ and ReX₂ can enable the cold source effects in WSe₂ p-type FETs, achieving steep SS of 29-38 mV/dec and high on/off ratios of (2.3-5.6)×10⁷. Moreover, multilayer ReS₂ retains the cold metal characteristic, thus ensuring similar CS-FET performances to that of the monolayer source. This work underlines the significance of cold metals for the design of p-type CS-FETs.

Ferroelectrics are a type of material with a polar structure and their polarization direction can be inverted reversibly by applying an electric field. They have attracted tremendous attention for their extensive applications in non-volatile memory, sensors and neuromorphic computing. However, conventional ferroelectric materials face insulating and interfacial issues in the commercialization process. In contrast, two-dimensional (2D) ferroelectric materials usually have excellent semiconductor performance, clean van der Waals interfaces and robust ferroelectric order in atom-thick layers, and hold greater promise for constructing multifunctional ferroelectric optoelectronic devices and nondestructive ultra-high-density memory. Recently, 2D ferroelectrics have obtained impressive breakthroughs, showing overwhelming superiority. Herein, firstly, the progress of experimental research on 2D ferroelectric materials is reviewed. Then, the preparation of 2D ferroelectric devices and their applications are discussed. Finally, the future development trend of 2D ferroelectrics is looked at.

Recently, β-Ga₂O₃, an ultra-wide bandgap semiconductor, has shown great potential to be used in power devices blessed with its unique material properties. For instance, the measured average critical field of the vertical Schottky barrier diode (SBD) based on β-Ga₂O₃ has reached 5.45 MV/cm, and no device in any material has measured a greater before. However, the high electric field of the β-Ga₂O₃ SBD makes it challenging to manage the electric field distribution and leakage current. Here, we show β-Ga₂O₃ junction barrier Schottky diode with NiO p-well floating field rings (FFRs). For the central anode, we filled a circular trench array with NiO to reduce the surface field under the Schottky contact between them to reduce the leakage current of the device. For the anode edge, experimental results have demonstrated that the produced NiO/β-Ga₂O₃ heterojunction FFRs enable the spreading of the depletion region, thereby mitigating the crowding effect of electric fields at the anode edge. Additionally, simulation results indicated that the p-NiO field plate structure designed at the edges of the rings and central anode can further reduce the electric field. This work verified the feasibility of the heterojunction FFRs in β-Ga₂O₃ devices based on the experimental findings and provided ideas for managing the electric field of β-Ga₂O₃ SBD.

The performance of optical interconnection has improved dramatically in recent years. Silicon-based optoelectronic heterogeneous integration is the key enabler to achieve high performance optical interconnection, which not only provides the optical gain which is absent from native Si substrates and enables complete photonic functionalities on chip, but also improves the system performance through advanced heterogeneous integrated packaging. This paper reviews recent progress of silicon-based optoelectronic heterogeneous integration in high performance optical interconnection. The research status, development trend and application of ultra-low loss optical waveguides, high-speed detectors, high-speed modulators, lasers and 2D, 2.5D, 3D and monolithic integration are focused on.

Transient memories, which can physically disappear without leaving traceable remains over a period of normal operation, are attracting increasing attention for potential applications in the fields of data security and green electronics. Resistive random access memory (RRAM) is a promising candidate for next-generation memory. In this context, biocompatible $\iota $-carrageenan ($\iota $-car), extracted from natural seaweed, is introduced for the fabrication of RRAM devices (Ag/$\iota $-car/Pt). Taking advantage of the complexation processes between the functional groups (C-O-C, C-O-H, et al.) and Ag metal ions, a lower migration barrier of Ag ions and a high-speed switching (22.2 ns for SET operation/26 ns for RESET operation) were achieved, resulting in an ultralow power consumption of 56 fJ. And the prepared Ag/$\iota $-car/Pt RRAM devices also revealed the capacities of multilevel storage and flexibility. In addition, thanks to the hydrophilic groups of $\iota $-car molecule, the RRAM devices can be rapidly dissolved in deionized (DI) water within 13 minutes, showing excellent transient characteristics. This work demonstrates that $\iota $-car based RRAM devices have great potential for applications in secure storage applications, flexible electronics and transient electronics.

Supercapacitor has been widely known as a representative electrochemical energy storage device with high power density and long lifespan. Recently, with the deeper understanding of its charge storage mechanism, unidirectional-charging supercapacitor, also called supercapacitor diode (CAPode), is successfully developed based on the ion-sieving effect of its working electrode towards electrolyte ions. Because CAPode integrates mobile ion and mobile electron in one hybrid circuit, it has a great potential in the emerging fields of ion/electron coupling logic operations, human-machine interface, neural network interaction, and in vivo diagnosis and treatment. Accordingly, we herein elucidate the working mechanism and design philosophy of CAPode, and summarize the electrode materials that are suitable for constructing CAPode. Meanwhile, some other supercapacitor-based devices beyond CAPode are also introduced, and their potential applications are instructively presented. Finally, we outline the challenges and chances of CAPode-related techniques.

AI development has brought great success to upgrading the information age. At the same time, the large-scale artificial neural network for building AI systems is thirsty for computing power, which is barely satisfied by the conventional computing hardware. In the post-Moore era, the increase in computing power brought about by the size reduction of CMOS in very large-scale integrated circuits (VLSIC) is challenging to meet the growing demand for AI computing power. To address the issue, technical approaches like neuromorphic computing attract great attention because of their feature of breaking Von-Neumann architecture, and dealing with AI algorithms much more parallelly and energy efficiently. Inspired by the human neural network architecture, neuromorphic computing hardware is brought to life based on novel artificial neurons constructed by new materials or devices. Although it is relatively difficult to deploy a training process in the neuromorphic architecture like spiking neural network (SNN), the development in this field has incubated promising technologies like in-sensor computing, which brings new opportunities for multidisciplinary research, including the field of optoelectronic materials and devices, artificial neural networks, and microelectronics integration technology. The vision chips based on the architectures could reduce unnecessary data transfer and realize fast and energy-efficient visual cognitive processing. This paper reviews firstly the architectures and algorithms of SNN, and artificial neuron devices supporting neuromorphic computing, then the recent progress of in-sensor computing vision chips, which all will promote the development of AI.

Neuromorphic devices that mimic the information processing function of biological synapses and neurons have attracted considerable attention due to their potential applications in brain-like perception and computing. In this paper, neuromorphic transistors with W-doped In₂O₃ nanofibers as the channel layers are fabricated and optoelectronic synergistic synaptic plasticity is also investigated. Such nanofiber transistors can be used to emulate some biological synaptic functions, including excitatory postsynaptic current (EPSC), long-term potentiation (LTP), and depression (LTD). Moreover, the synaptic plasticity of the nanofiber transistor can be synergistically modulated by light pulse and electrical pulse. At last, pulsed light learning and pulsed electrical forgetting behaviors were emulated in 5× 5 nanofiber device array. Our results provide new insights into the development of nanofiber optoelectronic neuromorphic devices with synergistic synaptic plasticity.