Jin‐Hong Park

Abstract The priority of synaptic device researches has been given to prove the device potential for the emulation of synaptic dynamics and not to functionalize further synaptic devices for more complex learning. Here, we demonstrate an optic-neural synaptic device by implementing synaptic and optical-sensing functions together on h -BN/WSe 2 heterostructure. This device mimics the colored and color-mixed pattern recognition capabilities of the human vision system when arranged in an optic-neura

Abstract Recently, negative differential resistance devices have attracted considerable attention due to their folded current–voltage characteristic, which presents multiple threshold voltage values. Because of this remarkable property, studies associated with the negative differential resistance devices have been explored for realizing multi-valued logic applications. Here we demonstrate a negative differential resistance device based on a phosphorene/rhenium disulfide (BP/ReS 2 ) heterojunctio

In spite of the recent heightened interest in molybdenum disulfide (MoS2) as a two-dimensional material with substantial bandgaps and reasonably high carrier mobility, a method for the layer-controlled and large-scale synthesis of high quality MoS2 films has not previously been established. Here, we demonstrate that layer-controlled and large-area CVD MoS2 films can be achieved by treating the surfaces of their bottom SiO2 substrates with the oxygen plasma process. Raman mapping, UV-Vis, and PL

Abstract Recently, research interest in brain‐inspired neuromorphic computing based on robust and intelligent artificial neural networks has surged owing to the ability of such technology to facilitate massive parallel, low‐power, highly adaptive, and event‐driven computing. Here, a photosynaptic device with a novel weight updating mechanism for high‐speed and low‐power optoelectronic spike processing is proposed, wherein a synaptic weight is controlled by a mixed spike consisting of voltage and

Most doping research into transition metal dichalcogenides (TMDs) has been mainly focused on the improvement of electronic device performance. Here, the effect of self‐assembled monolayer (SAM)‐based doping on the performance of WSe 2 ‐ and MoS 2 ‐based transistors and photodetectors is investigated. The achieved doping concentrations are ≈1.4 × 10 11 for octadecyltrichlorosilane (OTS) p‐doping and ≈10 11 for aminopropyltriethoxysilane (APTES) n‐doping (nondegenerate). Using this SAM doping tech

An ultrahigh performance MoS2 photodetector with high photoresponsivity (1.94 × 10(6) A W(-1) ) and detectivity (1.29 × 10(12) Jones) under 520 nm and 4.63 pW laser exposure is demonstrated. This photodetector is based on a methyl-ammonium lead halide perovskite/MoS2 hybrid structure with (3-aminopropyl)triethoxysilane doping. The performance degradation caused by moisture is also minimized down to 20% by adopting a new encapsulation bilayer of octadecyltrichlorosilane/polymethyl methacrylate.

Recently, MXenes, which are 2D early transition metal carbides and carbonitrides, have attracted wide attention because of their excellent conductivities. Here, the electrode applications of Ti 2 C(OH) x F y , one member of the MXene family, in WSe 2 and MoS 2 field effect transistors (FETs) are assessed. Kelvin probe force microscopy analysis is performed to determine its work function, which is estimated to be ≈4.98 eV. Devices based on WSe 2 /Ti 2 C(OH) x F y and MoS 2 /Ti 2 C(OH) x F y heter

A high-performance ReS2 -based thin-film transistor and photodetector with high on/off-current ratio (10(4) ), high mobility (7.6 cm(2) V(-1) s(-1) ), high photoresponsivity (2.5 × 10(7) A W(-1) ), and fast temporal response (rising and decaying time of 670 ms and 5.6 s, respectively) through O2 plasma treatment is reported.

Recently, three-terminal synaptic devices have attracted considerable attention owing to their nondestructive weight-update behavior, which is attributed to the completely separated terminals for reading and writing. However, the structural limitations of these devices, such as a low array density and complex line design, are predicted to result in low processing speeds and high energy consumption of the entire system. Here, we propose a vertical three-terminal synapse featuring a remote weight

Brain-inspired parallel computing, which is typically performed using a hardware neural-network platform consisting of numerous artificial synapses, is a promising technology for effectively handling large amounts of informational data. However, the reported nonlinear and asymmetric conductance-update characteristics of artificial synapses prevent a hardware neural-network from delivering the same high-level training and inference accuracies as those delivered by a software neural-network. Here,

We report the preparation of thickness-controlled few-layer black phosphorus (BP) films through the modulated plasma treatment of BP flakes. Not only does the plasma treatment control the thickness of the BP film, it also removes the chemical degradation of the exposed oxidized BP surface, which results in enhanced field-effect transistor (FET) performance. Our fabricated BP FETs were passivated with poly(methyl methacrylate) (PMMA) immediately after the plasma etching process. With these techni

Since the rediscovery of graphene in 2004, this material has attracted an enormous amount of interest owing to its unique structural, mechanical, electronic, and optical properties. Beyond this, the unique properties of graphene have also triggered extensive research on other two‐dimensional (2D) materials including transition metal dichalcogenides (TMDs), particularly for electronic and optoelectronic device applications. In particular, not only single junction but also various heterojunction d

The effects of triphenylphosphine (PPh3 )-based n-doping and hexagonal boron nitride (h-BN) insertion on a tungsten diselenide (WSe2 ) photodetector are systematically studied, and a very high performance WSe2 /h-BN heterostucture-based photodetector is demonstrated with a record photoresponsivity (1.27 × 10(6) A W(-1) ) and temporal photoresponse (rise time: 2.8 ms, decay time: 20.8 ms) under 520 nm wavelength and 5 pW power laser illumination.

Despite heightened interest in 2D transition-metal dichalcogenide (TMD) doping methods for future layered semiconductor devices, most doping research is currently limited to molybdenum disulfide (MoS2), which is generally used for n-channel 2D transistors. In addition, previously reported TMD doping techniques result in only high-level doping concentrations (degenerate) in which TMD materials behave as near-metallic layers. Here, we demonstrate a controllable nondegenerate p-type doping (p-dopin

Abstract Optogenetics refers to a technique that uses light to modulate neuronal activity with a high spatiotemporal resolution, which enables the manipulation of learning and memory functions in the human brain. This strategy of controlling neuronal activity using light can be applied for the development of intelligent systems, including neuromorphic and in‐memory computing systems. Herein, a flexible van der Waals (vdW) optoelectronic synapse is reported, which is a core component of optogenet