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Photodetectors are essential optoelectronic devices that play a critical role in modern technology by converting optical signals into electrical signals, which are one of the most important sensors of the informational devices in current 'Internet of Things' era. Two-dimensional (2D) material-based photodetectors have excellent performance, simple design and effortless fabrication processes, as well as enormous potential for fabricating highly integrated and efficient optoelectronic devices, which has attracted extensive research attention in recent years. The introduction of spontaneous polarization ferroelectric materials further enhances the performance of 2D photodetectors, moreover, companying with the reduction of power consumption. This article reviews the recent advances of materials, devices in ferroelectric-modulated photodetectors. This review starts with the introduce of the basic terms and concepts of the photodetector and various ferroelectric materials applied in 2D photodetectors, then presents a variety of typical device structures, fundamental mechanisms and potential applications under ferroelectric polarization modulation. Finally, we summarize the leading challenges currently confronting ferroelectric-modulated photodetectors and outline their future perspectives. [ABSTRACT FROM AUTHOR]

Ferroelectric materials have shown great value in the modern semiconductor industry and are considered important function materials due to their high dielectric constant and tunable spontaneous polarization. A ferroelectric field effect transistor (FeFET) is a field effect transistor (FET) with ferroelectric polarization field introduced to regulate carriers in semiconductors. With the coupling of ferroelectric and semiconductor, FeFETs are attractive for advanced electronic and optoelectronic applications, including emerging memories, artificial neural networks, high-performance photodetectors, and smart sensors. In this review, representative research results of FeFETs are reviewed from the perspective of structures and applications. Here, the background and significance of ferroelectrics and FeFETs are given. Furthermore, methods of building FeFETs in different structures and physical models describing the characteristics of FeFET are introduced. Important applications of FeFETs in electronics and optoelectronics are presented, with a comparison of performance between FeFETs and FETs without ferroelectrics, including memories and memristive devices, photodetectors, negative capacitance FETs, sensors, and multifunctional devices. Finally, based on the above discussions, promising applications and challenges of FeFETs are summarized. [ABSTRACT FROM AUTHOR]

Neuromorphic machines are intriguing for building energy-efficient intelligent systems, where spiking neurons are pivotal components. Recently, memristive neurons with promising bio-plausibility have been developed, but with limited reliability, bulky capacitors or additional reset circuits. Here, we propose an anti-ferroelectric field-effect transistor neuron based on the inherent polarization and depolarization of Hf0.2Zr0.8O2 anti-ferroelectric film to meet these challenges. The intrinsic accumulated polarization/spontaneous depolarization of Hf0.2Zr0.8O2 films implements the integration/leaky behavior of neurons, avoiding external capacitors and reset circuits. Moreover, the anti-ferroelectric neuron exhibits low energy consumption (37 fJ/spike), high endurance (>1012), high uniformity and high stability. We further construct a two-layer fully ferroelectric spiking neural networks that combines anti-ferroelectric neurons and ferroelectric synapses, achieving 96.8% recognition accuracy on the Modified National Institute of Standards and Technology dataset. This work opens the way to emulate neurons with anti-ferroelectric materials and provides a promising approach to building high-efficient neuromorphic hardware. The scalability of neuromorphic devices depends on the dismissal of capacitors and additional circuits. Here Liu et al. report an artificial neuron based on the polarization and depolarization of an anti-ferroelectric film, avoiding additional elements and reaching 37 fJ/spike of power consumption. [ABSTRACT FROM AUTHOR]

2D transition metal dichalcogenides (TMDs) are promising semiconductive films for applications in future devices due to their prosperous and tunable band structures. However, most TMD‐based top gate transistors suffer from a significant doping effect in the channel due to the subsequent deposition high‐k dielectric layer and metal gate, which limits their practical applications. In this work, the channel doping effect caused by various processing steps based on mechanical exfoliated MoS2 sheets is systematically investigated. This work illustrates a clear correlation among these steps and provides a simple and efficient methodology to realize high‐performance enhancement mode MoS2 field effect transistors, which can be extended to other 2D materials. [ABSTRACT FROM AUTHOR]

The separation of processing and memory units in von Neumann architecture creates issues with energy consumption and speed mismatches, which is a huge obstacle on the road of integrated-circuit development. Potentially, the excellent performance of two-dimensional materials field-effect transistors controlled by organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) polymer could clear the path for the development of next-generation microelectronics. Here, we combined P(VDF-TrFE) polymer and molybdenum disulfide (MoS2) nanoflakes to fabricate a horizontal dual-gate ferroelectric field-effect transistor (HDG-FeFET) device. This device can provide in-situ memory of logic results while processing the AND logic function. During the logic operations, the logic output state-1/state-0 current ratio approached 105. After 900 s, the corresponding non-volatile memory state-1/state-0 current ratio remains at 104. This type of transistor is expected to provide a promising in-memory computing solution for next-generation computing architecture. [ABSTRACT FROM AUTHOR]

A transparent, flexible graphene field effect transistor (GFET) based on ferroelectric gate is demonstrated. In this device, the single layer graphene was fabricated by chemical vapor deposition method, and transferred to the polyethylene terephthalate substrate. Then the poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) ferroelectric polymer layer film was used as the gate dielectric for the graphene FET. Based on the P(VDF-TrFE)/graphene heterojunction FET, Hall Bar structure was fabricated. The transport properties of the graphene channel at low temperature and retention characteristics at different temperature are investigated in detail. These special properties indicated that the GFET might be useful for many particular applications, such as a non-volatile memories, flexible electronic devices and phototransistors. [ABSTRACT FROM AUTHOR]

Semiconductive transition metal dichalcogenides (TMDs) have been considered as next generation semiconductors, but to date most device investigations are still based on microscale exfoliation with a low yield. Wafer scale growth of TMDs has been reported but effective doping approaches remain challenging due to their atomically thick nature. This work reports the synthesis of wafer‐scale continuous few‐layer PtSe2 films with effective doping in a controllable manner. Chemical component analyses confirm that both n‐doping and p‐doping can be effectively modulated through a controlled selenization process. The electrical properties of PtSe2 films have been systematically studied by fabricating top‐gated field effect transistors (FETs). The device current on/off ratio is optimized in two‐layer PtSe2 FETs, and four‐terminal configuration displays a reasonably high effective field effect mobility (14 and 15 cm2 V−1 s−1 for p‐type and n‐type FETs, respectively) with a nearly symmetric p‐type and n‐type performance. Temperature dependent measurement reveals that the variable range hopping is dominant at low temperatures. To further establish feasible application based on controllable doping of PtSe2, a logic inverter and vertically stacked p–n junction arrays are demonstrated. These results validate that PtSe2 is a promising candidate among the family of TMDs for future functional electronic applications. An improved method for the synthesis of wafer‐scale continuous PtSe2 films with an effective doping strategy in a controllable manner is developed. Nearly symmetric n‐type and p‐type field‐effect transistors have been fabricated, based on which logic inverter and vertically stacked p–n junction arrays are successfully demonstrated in wafer scale, which enable potential applications in future 2D material circuits. [ABSTRACT FROM AUTHOR]

Negative capacitance field‐effect transistors (NCFETs) achieve ultra‐low sub‐threshold swing through internal voltage amplification, stemming from the negative capacitance effect during the ferroelectric polarization switching process. In article number 1800231, Jianlu Wang and co‐workers review the theoretical and experimental results of NCFETs based on various gate structures and typical ferroelectrics. Novel NCFET structures, combined with 2D materials and FinFET, show great prospects for the future. [ABSTRACT FROM AUTHOR]

With the progress in silicon circuit miniaturization, lowering power consumption becomes the major objective. Supply voltage scaling in ultralarge‐scale integration (ULSI) is limited by the physical barrier termed "Boltzmann Tyranny." Moreover, considerable heat is inevitably generated from the ultrahighly integrated circuit. To solve these problems, a ferroelectric negative capacitance field‐effect transistor (Fe‐NCFET) is proposed in order to reduce the subthreshold swing (SS) through internal voltage amplification mechanism, thus effectively scaling the supply voltage and significantly lowering the power dissipation of ULSI. In this Review, representative research results on NCFET are comprehensively reviewed to offer benefits for further study. Here, the background and significance of NCFETs are introduced, and the physical essence of negative capacitance effect is reviewed. Then, physical models and simulation methods of NCFETs are classified and discussed under the consideration of three basic gate structures. Several influencing factors of device performance such as SS, on‐off ratio, and hysteresis, are also theoretically analyzed. Moreover, the experimental results of NCFETs based on different ferroelectric materials are summarized. Finally, with the combination of NC effect and two‐dimentional materials, FinFET, and tunneling FET, respectively, several novel and potential NCFETs are presented, and the outlook of NCFETs is proposed. Numerous representative research studies on ferroelectric negative capacitance field‐effect transistors (Fe‐NCFETs) are reviewed herein, including the physical mechanism of NC effect, physical models and simulation methods, experimental results of NCFETs based on three types of ferroelectric materials, and advanced NC‐based transistors such as 2D‐NCFET, NC‐FinFET, etc. Fe‐NCFET presents great potential for lowering the power dissipation of integrated circuits. [ABSTRACT FROM AUTHOR]