Showing papers on "Field-effect transistor published in 2020"

The future of ferroelectric field-effect transistor technology

Abstract: The discovery of ferroelectricity in oxides that are compatible with modern semiconductor manufacturing processes, such as hafnium oxide, has led to a re-emergence of the ferroelectric field-effect transistor in advanced microelectronics. A ferroelectric field-effect transistor combines a ferroelectric material with a semiconductor in a transistor structure. In doing so, it merges logic and memory functionalities at the single-device level, delivering some of the most pressing hardware-level demands for emerging computing paradigms. Here, we examine the potential of the ferroelectric field-effect transistor technologies in current embedded non-volatile memory applications and future in-memory, biomimetic and alternative computing models. We highlight the material- and device-level challenges involved in high-volume manufacturing in advanced technology nodes (≤10 nm), which are reminiscent of those encountered in the early days of high-K-metal-gate transistor development. We argue that the ferroelectric field-effect transistors can be a key hardware component in the future of computing, providing a new approach to electronics that we term ferroelectronics. This Perspective examines the use of ferroelectric field-effect transistor technologies in current embedded non-volatile memory applications and future in-memory, biomimetic and alternative computing models, arguing that the devices will be a key component in the development of data-centric computing.

Large-scale flexible and transparent electronics based on monolayer molybdenum disulfide field-effect transistors

Abstract: Atomically thin molybdenum disulfide (MoS2) is a promising semiconductor material for integrated flexible electronics due to its excellent mechanical, optical and electronic properties. However, the fabrication of large-scale MoS2-based flexible integrated circuits with high device density and performance remains a challenge. Here, we report the fabrication of transparent MoS2-based transistors and logic circuits on flexible substrates using four-inch wafer-scale MoS2 monolayers. Our approach uses a modified chemical vapour deposition process to grow wafer-scale monolayers with large grain sizes and gold/titanium/gold electrodes to create a contact resistance as low as 2.9 kΩ μm−1. The field-effect transistors are fabricated with a high device density (1,518 transistors per cm2) and yield (97%), and exhibit high on/off ratios (1010), current densities (~35 μA μm−1), mobilities (~55 cm2 V−1 s−1) and flexibility. We also use the approach to create various flexible integrated logic circuits: inverters, NOR gates, NAND gates, AND gates, static random access memories and five-stage ring oscillators. Wafer-scale monolayers of MoS2 can be used to create flexible transistors and circuits that exhibit on/off ratios of 1010, current densities of ~35 μA μm−1 and mobilities of ~55 cm2 V−1 s−1.

Evaporated tellurium thin films for p-type field-effect transistors and circuits

Abstract: There is an emerging need for semiconductors that can be processed at near ambient temperature with high mobility and device performance. Although multiple n-type options have been identified, the development of their p-type counterparts remains limited. Here, we report the realization of tellurium thin films through thermal evaporation at cryogenic temperatures for fabrication of high-performance wafer-scale p-type field-effect transistors. We achieve an effective hole mobility of ~35 cm2 V-1 s-1, on/off current ratio of ~104 and subthreshold swing of 108 mV dec-1 on an 8-nm-thick film. High-performance tellurium p-type field-effect transistors are fabricated on a wide range of substrates including glass and plastic, further demonstrating the broad applicability of this material. Significantly, three-dimensional circuits are demonstrated by integrating multi-layered transistors on a single chip using sequential lithography, deposition and lift-off processes. Finally, various functional logic gates and circuits are demonstrated.

Lateral 2D WSe2 p-n Homojunction Formed by Efficient Charge-Carrier-Type Modulation for High-Performance Optoelectronics.

Abstract: As unique building blocks for next-generation optoelectronics, high-quality 2D p-n junctions based on semiconducting transition metal dichalcogenides (TMDs) have attracted wide interest, which are urgent to be exploited. Herein, a novel and facile electron doping of WSe2 by cetyltrimethyl ammonium bromide (CTAB) is achieved for the first time to form a high-quality intramolecular p-n junction with superior optoelectronic properties. Efficient manipulation of charge carrier type and density in TMDs via electron transfer between Br- in CTAB and TMDs is proposed theoretically by density functional theory (DFT) calculations. Compared with the intrinsic WSe2 photodetector, the switching light ratio (Ilight /Idark ) of the p-n junction device can be enhanced by 103 , and the temporal response is also dramatically improved. The device possesses a responsivity of 30 A W-1 , with a specific detectivity of over 1011 Jones. In addition, the mechanism of charge transfer in CTAB-doped 2D WSe2 and WS2 are investigated by designing high-performance field effect transistors. Besides the scientific insight into the effective manipulation of 2D materials by chemical doping, this work presents a promising applicable approach toward next-generation photoelectronic devices with high efficiency.

Low-voltage 2D materials-based printed field-effect transistors for integrated digital and analog electronics on paper

Abstract: Paper is the ideal substrate for the development of flexible and environmentally sustainable ubiquitous electronic systems, which, combined with two-dimensional materials, could be exploited in many Internet-of-Things applications, ranging from wearable electronics to smart packaging. Here we report high-performance MoS2 field-effect transistors on paper fabricated with a “channel array” approach, combining the advantages of two large-area techniques: chemical vapor deposition and inkjet-printing. The first allows the pre-deposition of a pattern of MoS2; the second, the printing of dielectric layers, contacts, and connections to complete transistors and circuits fabrication. Average ION/IOFF of 8 × 103 (up to 5 × 104) and mobility of 5.5 cm2 V−1 s−1 (up to 26 cm2 V−1 s−1) are obtained. Fully functional integrated circuits of digital and analog building blocks, such as logic gates and current mirrors, are demonstrated, highlighting the potential of this approach for ubiquitous electronics on paper. Paper is a promising substrate for flexible and environmentally sustainable electronic devices. Here, the authors combine chemical vapor deposition of MoS2 with inkjet printing of a hexagonal boron nitride (hBN) dielectric and silver electrodes, to fabricate flexible MoS2 field-effect transistors on paper, and then combine the latter with printed graphene resistors and silver interconnects to create inverters, logic gates and current mirrors.

Progress of Ultra-Wide Bandgap Ga 2 O 3 Semiconductor Materials in Power MOSFETs

Abstract: As a promising ultra-wide bandgap semiconductor, the β-phase of Ga 2 O 3 has attracted more and more interest in the field of power electronics due to its ultra-wide bandgap (4.8 eV), high theoretical breakdown electric field (8 MV/cm), and large Baliga's figure of merit, which is deemed as a potential candidate for next generation high-power electronics, including diodes, field effect transistors (FETs), etc. In this article, we introduce the basic material properties of Ga 2 O 3 , and review the recent progress and advances of β-Ga 2 O 3 based metal-oxide-semiconductor field-effect transistors (MOSFETs). Due to the problematic p-type doping technology up to now, the enhancement-mode (E-mode) β-Ga 2 O 3 FETs face more difficulties, compared with depletion mode (D-mode). This article focuses on reviewing the recent progress of E-mode Ga 2 O 3 MOSFETs, summarizing and comparing various feasible solutions when p-type doping is absent. Furthermore, the device fabrication and performances of state-of-art β-Ga 2 O 3 MOSFETs, including D-mode, E-mode, and planar/vertical structure are fully discussed and compared, as well as potential solutions to the challenges of Ga 2 O 3 FETs.

Electrical characterization of 2D materials-based field-effect transistors

Abstract: Two-dimensional (2D) materials hold great promise for future nanoelectronics as conventional semiconductor technologies face serious limitations in performance and power dissipation for future technology nodes. The atomic thinness of 2D materials enables highly scaled field-effect transistors (FETs) with reduced short-channel effects while maintaining high carrier mobility, essential for high-performance, low-voltage device operations. The richness of their electronic band structure opens up the possibility of using these materials in novel electronic and optoelectronic devices. These applications are strongly dependent on the electrical properties of 2D materials-based FETs. Thus, accurate characterization of important properties such as conductivity, carrier density, mobility, contact resistance, interface trap density, etc is vital for progress in the field. However, electrical characterization methods for 2D devices, particularly FET-related measurement techniques, must be revisited since conventional characterization methods for bulk semiconductor materials often fail in the limit of ultrathin 2D materials. In this paper, we review the common electrical characterization techniques for 2D FETs and the related issues arising from adapting the techniques for use on 2D materials.

A solvent-based surface cleaning and passivation technique for suppressing ionic defects in high-mobility perovskite field-effect transistors

Abstract: Organometal halide perovskite semiconductors could potentially be used to create field-effect transistors (FETs) with high carrier mobilities. However, the performance of these transistors is currently limited by the migration of ionic surface defects. Here, we show that a surface cleaning and passivation technique, which is based on a sequence of three solution-based steps, can reduce the concentration of ionic surface defects in halide-based perovskites without perturbing the crystal lattice. The approach consists of an initial cleaning step using a polar/nonpolar solvent, a healing step to remove surface organic halide vacancies and a second cleaning step. The surface treatment is shown to restore clean, near hysteresis-free transistor operation, even if the perovskite films are formed under non-optimized conditions, and can improve room-temperature FET mobility by two to three orders of magnitude compared to untreated films. Our methylammonium lead iodide (MAPbI3) FETs exhibit high n- and p-type mobilities of 3.0 cm2 V−1 s−1 and 1.8 cm2 V−1 s−1, respectively, at 300 K, and higher values (9.2 cm2 V−1 s−1; n-type) at 80 K. We also show that the approach can be used to transform PbI2 single crystals into high-quality, two-dimensional perovskite single crystals. A three-stage solution-based cleaning technique can increase the room-temperature mobility and reduce the hysteresis of organometal halide perovskite transistors by decreasing the surface defects in the perovskite films.

Lateral β-Ga2O3 field effect transistors

Abstract: Beta phase Gallium Oxide (BGO) is an emerging ultra-wide bandgap semiconductor with disruptive potential for ultra-low power loss, high-efficiency power applications. The critical field strength is the key enabling material parameter of BGO which allows sub-micrometer lateral transistor geometry. This property combined with ion-implantation technology and large area native substrates result in exceptionally low conduction losses, faster power switching frequency and even radio frequency power. We present a review of BGO epitaxial materials and lateral field-effect transistors developments, highlight early achievements and discuss engineering solutions with power switching and radio frequency applications in mind.

High-Performance Flexible Nanoscale Field-Effect Transistors Based on Transition Metal Dichalcogenides

Abstract: Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) are good candidates for high-performance flexible electronics. However, most demonstrations of such flexible field-effect transistors (FETs) to date have been on the micron scale, not benefitting from the short-channel advantages of 2D-TMDs. Here, we demonstrate flexible monolayer MoS2 FETs with the shortest channels reported to date (down to 50 nm) and remarkably high on-current (up to 470 uA/um at 1 V drain-to-source voltage) which is comparable to flexible graphene or crystalline silicon FETs. This is achieved using a new transfer method wherein contacts are initially patterned on the rigid TMD growth substrate with nanoscale lithography, then coated with a polyimide (PI) film which becomes the flexible substrate after release, with the contacts and TMD. We also apply this transfer process to other TMDs,reporting the first flexible FETs with MoSe2 and record on-current for flexible WSe2 FETs. These achievements push 2D semiconductors closer to a technology for low-power and high-performance flexible electronics.

Nonvolatile ferroelectric field-effect transistors.

Abstract: Future data-intensive applications will have integrated circuit architectures combining energy-efficient transistors, high-density data storage and electro-optic sensing arrays in a single chip to perform in situ processing of captured data. The costly dense wire connections in 3D integrated circuits and in conventional packaging and chip-stacking solutions could affect data communication bandwidths, data storage densities, and optical transmission efficiency. Here we investigated all-ferroelectric nonvolatile LiNbO3 transistors to function through redirection of conducting domain walls between the drain, gate and source electrodes. The transistor operates as a single-pole, double-throw digital switch with complementary on/off source and gate currents controlled using either the gate or source voltages. The conceived device exhibits high wall current density and abrupt off-and-on state switching without subthreshold swing, enabling nonvolatile memory-and-sensor-in-logic and logic-in-memory-and-sensor capabilities with superior energy efficiency, ultrafast operation/communication speeds, and high logic/storage densities. There is growing interest in non-traditional materials for logic applications. Here, the authors demonstrate a domain device architecture based on ferroelectric LiNbO3 crystals with gate voltage controlled transistor without subthreshold swing and source voltage controlled nonvolatile transistor.

Light‐Driven WSe2‐ZnO Junction Field‐Effect Transistors for High‐Performance Photodetection

Abstract: Assembling nanomaterials into hybrid structures provides a promising and flexible route to reach ultrahigh responsivity by introducing a trap-assisted gain (G) mechanism. However, the high-gain photodetectors benefitting from long carrier lifetime often possess slow response time (t) due to the inherent G-t tradeoff. Here, a light-driven junction field-effect transistor (LJFET), consisting of an n-type ZnO belt as the channel material and a p-type WSe2 nanosheet as a photoactive gate material, to break the G-t tradeoff through decoupling the gain from carrier lifetime is reported. The photoactive gate material WSe2 under illumination enables a conductive path for externally applied voltage, which modulates the depletion region within the ZnO channel efficiently. The gain and response time are separately determined by the field effect modulation and the switching speed of LJFET. As a result, a high responsivity of 4.83 × 103 A W-1 with a gain of ≈104 and a rapid response time of ≈10 µs are obtained simultaneously. The LJFET architecture offers a new approach to realize high-gain and fast-response photodetectors without the G-t tradeoff.

Graphene Based Low Voltage Field Effect Transistor Coupled with Biodegradable Piezoelectric Material Based Dynamic Pressure Sensor.

Abstract: Pressure sensors form the basic building block for realization of an electronic or tactile skin used in prothesis, robotics, and other similar applications. This paper presents a device consisting of biodegradable piezoelectric material based dynamic pressure sensor coupled with a graphene field-effect-transistor (GFET) operated at very low voltage (50 mV). The device has a biodegradable β-glycine/chitosan composite based metal-insulator-metal (MIM) structure connected with GFET in an extended gate configuration. The developed device shows a sensitivity of 2.70 × 10-4 kPa-1 for a pressure range of 5-20 kPa and 7.56 × 10-4 kPa-1 for a pressure range between 20 and 35 kPa. A distinctive feature of the presented device is its very low operation voltage, which offers a significant advantage toward the development of energy efficient large-area electronic skin. Further, the biodegradability of piezoelectric material makes the presented sensors useful in terms of reduced electronic waste, which is currently another growing area of interest.

Interlayer Band-to-Band Tunneling and Negative Differential Resistance in van der Waals BP/InSe Field-Effect Transistors

Abstract: Atomically thin layers of van der Waals (vdW) crystals offer an ideal material platform to realize tunnel field effect transistors (TFETs) that exploit the tunneling of charge carriers across the forbidden gap of a vdW heterojunction. This type of device requires a precise energy band alignment of the different layers of the junction to optimize the tunnel current. Amongst two-dimensional (2D) vdW materials, black phosphorus (BP) and indium selenide (InSe) have a Brillouin zone-centered conduction and valence bands, and a type II band offset, both ideally suited for band-to-band tunneling. Here, we demonstrate TFETs based on BP/InSe heterojunctions with diverse electrical transport characteristics: forward rectifying, Zener-tunneling and backward rectifying characteristics are realized in BP/InSe junctions with different thickness of the BP layer or by electrostatic gating of the junction. Electrostatic gating yields a large on/off current ratio of up to 108 and negative differential resistance at low applied voltages (V ~ 0.2V). These findings illustrate versatile functionalities of TFETs based on BP and InSe, offering opportunities for applications of these 2D materials beyond the device architectures reported in the current literature.

A transverse tunnelling field-effect transistor made from a van der Waals heterostructure

Abstract: Semiconductor devices that rely on quantum tunnelling could be of use in logic, memory and radiofrequency applications. Tunnel devices that exhibit negative differential resistance typically follow an operating principle in which the tunnelling current contributes directly to the drive current. Here, we report a tunnelling field-effect transistor made from a black phosphorus/Al2O3/black phosphorus van der Waals heterostructure in which the tunnelling current is in the transverse direction with respect to the drive current. Through an electrostatic effect, this tunnelling current can induce a drastic change in the output current, leading to a tunable negative differential resistance with a peak-to-valley ratio of more than 100 at room temperature. Our device also exhibits abrupt switching, with a body factor (the relative change in gate voltage with respect to that of the surface potential) that is one-tenth of the Boltzmann limit for conventional transistors across a wide temperature range. A black phosphorus/Al2O3/black phosphorus heterostructure can be used to create a tunnel field-effect transistor in which the tunnelling current is in the transverse direction with respect to the drive current, leading to abrupt switching and a negative differential resistance with a peak-to-valley ratio of more than 100 at room temperature.

Back-End, CMOS-Compatible Ferroelectric Field-Effect Transistor for Synaptic Weights.

Abstract: Neuromorphic computing architectures enable the dense colocation of memory and processing elements within a single circuit. This colocation removes the communication bottleneck of transferring data between separate memory and computing units as in standard von Neuman architectures for data-critical applications including machine learning. The essential building blocks of neuromorphic systems are nonvolatile synaptic elements such as memristors. Key memristor properties include a suitable nonvolatile resistance range, continuous linear resistance modulation, and symmetric switching. In this work, we demonstrate voltage-controlled, symmetric and analog potentiation and depression of a ferroelectric Hf0.57Zr0.43O2 (HZO) field-effect transistor (FeFET) with good linearity. Our FeFET operates with low writing energy (fJ) and fast programming time (40 ns). Retention measurements have been performed over 4 bit depth with low noise (1%) in the tungsten oxide (WOx) readout channel. By adjusting the channel thickness from 15 to 8 nm, the on/off ratio of the FeFET can be engineered from 1 to 200% with an on-resistance ideally >100 kΩ, depending on the channel geometry. The device concept is using earth-abundant materials and is compatible with a back end of line (BEOL) integration into complementary metal-oxide-semiconductor (CMOS) processes. It has therefore a great potential for the fabrication of high-density, large-scale integrated arrays of artificial analog synapses.

Graphene-based field-effect transistor biosensors for the rapid detection and analysis of viruses: A perspective in view of COVID-19

Abstract: Current situation of COVID-19 demands a rapid, reliable, cost-effective, facile detection strategy to break the transmission chain and biosensor has emerged as a feasible solution for this purpose. Introduction of nanomaterials has undoubtedly improved the performance of biosensor and the addition of graphene enhanced the sensing ability to a peerless level. Amongst different graphene-based biosensing schemes, graphene field-effect transistor marked its unique presence owing to its ability of ultrasensitive and low-noise detection thereby facilitating instantaneous measurements even in the presence of small amounts of analytes. Recently, graphene field-effect transistor type biosensor is even successfully employed in rapid detection of SARS-CoV-2 and this triggers the interest of the scientific community in reviewing the current developments in graphene field-effect transistor. Subsequently, in this article, the recent progress in graphene field-effect transistor type biosensors for the detection of the virus is reviewed and challenges along with their strengths are discussed.

High-performance 5.1 nm in-plane Janus WSeTe Schottky barrier field effect transistors.

Abstract: Using ab initio quantum-transport simulations, we studied the intrinsic transfer characteristics and benchmarks of the ballistic performance of 5.1 nm double-gated Schottky-barrier field effect transistors (SBFETs) consisting of in-plane (IP) heterojunctions of metallic-phase (1T or 1T') MTe2 (M = Ti, Zr, Hf, Cr, Mo, W) and semiconducting-phase (2H) WSe2, WTe2 and Janus WSeTe. The 2H-phase Janus WSeTe is a semiconductor with an indirect bandgap (1.26 eV), which is less than the bandgap of 2H-phase WSe2 (1.64 eV) and is greater than the bandgap of 2H-phase WTe2 (1.02 eV). The band alignments show that all IP 1T/2H contacts are Schottky-barrier contacts with the Fermi levels of 1T or 1T' MTe2 (M = Ti, Zr, Hf, Cr, Mo, W) located within the bandgaps of 2H WSe2, WTe2 and Janus WSeTe. Although double-gated IP WSe2-SBFETs can satisfy the OFF current requirement, their ON currents all fall below the requirements of the high performance transistor outlined by the ITRS (International Technology Roadmap for Semiconductors, 2013 version) for the production year 2028. Double-gated IP WTe2-SBFETs cannot overcome the short channel effect leading to minimum drain currents all beyond the OFF current requirement of ITRS (2013 version) for the production year 2028. Fortunately, double-gated IP WSeTe-SBFETs with 1T MoTe2 or 1T' WTe2 electrodes can overcome the short channel effect and satisfy the requirements of the high-performance transistor outlined by the ITRS (2013 version) for the production year 2028.

A self-powered photodetector based on two-dimensional boron nanosheets

Abstract: Owing to their intriguing characteristics, the ongoing pursuit of emerging mono-elemental two-dimensional (2D) nanosheets beyond graphene is an exciting research area for next-generation applications. Herein, we demonstrate that highly crystalline 2D boron (B) nanosheets can be efficiently synthesized by employing a modified liquid phase exfoliation method. Moreover, carrier dynamics has been systematically investigated by using femtosecond time-resolved transient absorption spectroscopy, demonstrating an ultrafast recovery speed during carrier transfer. Based on these results, the optoelectronic performance of the as-synthesized 2D B nanosheets has been investigated by applying them in photoelectrochemical (PEC)-type and field effect transistor (FET)-type photodetectors. The experimental results revealed that the as-fabricated PEC device not only exhibited a favourable self-powered capability, but also a high photoresponsivity of 2.9-91.7 μA W-1 in the UV region. Besides, the FET device also exhibited a tunable photoresponsivity in the range of 174-281.3 μA W-1 under the irradiation of excited light at 405 nm. We strongly believe that the current work shall pave the path for successful utilization of 2D B nanosheets in electronic and optoelectronic devices. Moreover, the proposed method can be utilized to explore other mono-elemental 2D nanomaterials.

Highly Enhanced Gas Sensing Performance Using a 1T/2H Heterophase MoS2 Field-Effect Transistor at Room Temperature.

Abstract: Monolayer MoS2 (ML-MoS2) with various polymorphic phases attracts growing interests for device applications in recent years. Herein, a field-effect transistor (FET) gas sensor is developed on the basis of monolayer MoS2 with a heterophase of a 1T metallic phase and a 2H semiconducting phase. Lithium-exfoliated MoS2 nanosheets own a monolayer structure with rich active sites for gas adsorption. With thermal annealing from 50 to 300 °C, the initial lithium-exfoliated 1T-phase MoS2 gradually transforms into the 2H phase, during which the 1T and 2H heterophases can be modulated. The 1T/2H heterophase MoS2 shows p-type semiconducting properties and prominent adsorption capability for NO2 molecules. The highest response is observed for 100 °C annealed MoS2 of a 40% 1T phase and a 60% 2H phase, which shows a sensitivity up to 25% toward 2 ppm NO2 at room temperature in a very short time (10 s) and a lower limit of detection down to 25 ppb. This study demonstrates that the gas detection capability of ML-MoS2 could be boosted with the heterophase construction, which brings new insights into transition-metal dichalcogenide gas sensors.

Improved Contacts and Device Performance in MoS2 Transistors Using a 2D Semiconductor Interlayer.

Abstract: We report a contact engineering method to minimize the Schottky barrier height (SBH) and contact resistivity of MoS2 field-effect transistors (FETs) by using ultrathin 2D semiconductors as contact interlayers. We demonstrate that the addition of a few-layer MoSe2 between the MoS2 channel and Ti electrodes effectively reduces the SBH at the contacts from ∼100 to ∼25 meV, contact resistivity from ∼6 × 10-5 to ∼1 × 10-6 Ω cm2, and current transfer length from ∼425 to ∼60 nm. The drastic reduction of SBH can be attributed to the synergy of Fermi-level pinning close to the conduction band edge of the MoSe2 interlayer and favorable conduction-band offset between the MoSe2 interlayer and MoS2 channel. As a result of the improved contacts, MoS2 FETs with Ti/MoSe2 contacts also demonstrate higher two-terminal mobility.

Solution-Processed, Large-Area, Two-Dimensional Crystals of Organic Semiconductors for Field-Effect Transistors and Phototransistors.

Abstract: Organic electronics with π-conjugated organic semiconductors are promising candidates for the next electronics revolution. For the conductive channel, the large-area two-dimensional (2D) crystals o...

Optoelectronic synapse using monolayer MoS2 field effect transistors.

Abstract: Optical data sensing, processing and visual memory are fundamental requirements for artificial intelligence and robotics with autonomous navigation. Traditionally, imaging has been kept separate from the pattern recognition circuitry. Optoelectronic synapses hold the special potential of integrating these two fields into a single layer, where a single device can record optical data, convert it into a conductance state and store it for learning and pattern recognition, similar to the optic nerve in human eye. In this work, the trapping and de-trapping of photogenerated carriers in the MoS2/SiO2 interface of a n-channel MoS2 transistor was employed to emulate the optoelectronic synapse characteristics. The monolayer MoS2 field effect transistor (FET) exhibits photo-induced short-term and long-term potentiation, electrically driven long-term depression, paired pulse facilitation (PPF), spike time dependent plasticity, which are necessary synaptic characteristics. Moreover, the device's ability to retain its conductance state can be modulated by the gate voltage, making the device behave as a photodetector for positive gate voltages and an optoelectronic synapse at negative gate voltages.