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Performance analysis of a substrate-engineered monolayer MoS2 field-effect transistor
摘要： We investigate the impact of different substrates on the performance of a monolayer MoS2 field-effect transistor (FET) by calculating the interface charge density between the MoS2 layer and the substrate using first-principle calculations based on density functional theory to provide details about the overlap of electron orbitals at the interface. The electrical characteristics of the monolayer MoS2 FET are determined by using the extracted interface charge density in numerical simulations. The electron transport behavior of the monolayer MoS2 FET is modeled using the nonequilibrium Green’s function with mode space (NEGF_MS) approach. We study and compare the performance of monolayer MoS2 FETs on different substrates, viz. SiO2, HfSiO4, Si3N4, HfO2, and h-BN. The results reveal that the monolayer MoS2 FET on the h-BN/Si substrate exhibits an on-current of 548 μA/μm and a subthreshold swing of 65 mV/dec.
关键词： Carrier fluctuations,Electron transport,Charge density,NEGF_MS,Monolayer MoS2 FET
更新于2025-09-09 09:28:46
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Ionic modulation and ionic coupling effects in MoS2 devices for neuromorphic computing
摘要： Coupled ionic–electronic effects present intriguing opportunities for device and circuit development. In particular, layered two-dimensional materials such as MoS2 offer highly anisotropic ionic transport properties, facilitating controlled ion migration and efficient ionic coupling among devices. Here, we report reversible modulation of MoS2 films that is consistent with local 2H–1T′ phase transitions by controlling the migration of Li+ ions with an electric field, where an increase/decrease in the local Li+ ion concentration leads to the transition between the 2H (semiconductor) and 1T′ (metal) phases. The resulting devices show excellent memristive behaviour and can be directly coupled with each other through local ionic exchange, naturally leading to synaptic competition and synaptic cooperation effects observed in biology. These results demonstrate the potential of direct modulation of two-dimensional materials through field-driven ionic processes, and can lead to future electronic and energy devices based on coupled ionic–electronic effects and biorealistic implementation of artificial neural networks.
关键词： 2H–1T′ phase transitions,ionic modulation,MoS2 devices,synaptic cooperation,neuromorphic computing,ionic coupling,synaptic competition,memristive behaviour
更新于2025-09-09 09:28:46
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Ambipolar charge transport in an organic/inorganic van der Waals p–n heterojunction
摘要： Hybrid two-dimensional (2D) van der Waals (vdW) p–n junctions are attractive due to the controlled synthesis of the physical performances of organic semiconductors and quantum confinement effects of 2D materials, enabling highly tunable optoelectronic performances as well as low-cost processability. Here, hybrid 2D heterostructures are fabricated using a p-type semiconducting polymer (PDVT-10) and n-type MoS2. An ultra-thin film (B9 nm) of the PDVT-10 polymer is formed using the Langmuir–Schaefer (LS) technique. Large-scale MoS2 monolayers are prepared using a chemical vapor deposition (CVD) method. The PDVT-10/MoS2 vertical heterojunction devices show ambipolar charge transport properties with a p-type maximum field-effect mobility of 0.3 cm2 V(cid:2)1 s(cid:2)1 and an n-type maximum field-effect mobility of 2.45 cm2 V(cid:2)1 s(cid:2)1. In addition, the heterojunctions exhibit a great photoresponse under white light as well as a clear rectifying behavior.
关键词： PDVT-10,p–n heterojunction,organic/inorganic,van der Waals,ambipolar charge transport,MoS2
更新于2025-09-09 09:28:46
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High-Performance 2D MoS <sub/>2</sub> Phototransistor for Photo Logic Gate and Image Sensor
摘要： Two-dimensional (2D) MoS2 is a representative n-type transition-metal dichalcogenide (TMD) semiconductor that has great potential for future nanoscale electronic and optoelectronic applications. Here, we report a high-performance MoS2 phototransistor that exhibits a photoresponse in the 400?700 nm range with the maximum responsivity of over 1 × 104 A/W. As a more sophisticated optoelectronic application than a simple unit device, it is implemented in a photoinverter (NOT logic gate) connected to an external resistor, which clearly shows photoinduced static and dynamic characteristics. Furthermore, we demonstrate a prototype visible imager using the MoS2 photoinverter as imaging pixels as an excellent example of advanced developments in an optoelectronic system based on the 2D semiconductors.
关键词： two-dimensional van der Waals materials,MoS2,image sensor,phototransistor,graphene contact,photoinverter
更新于2025-09-09 09:28:46
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Relaxation and domain formation in incommensurate two-dimensional heterostructures
摘要： We introduce con?guration space as a natural representation for calculating the mechanical relaxation patterns of incommensurate two-dimensional (2D) bilayers. The approach can be applied to a wide variety of 2D materials through the use of a continuum model in combination with a generalized stacking fault energy for interlayer interactions. We present computational results for small-angle twisted bilayer graphene and molybdenum disul?de (MoS2), a representative material of the transition-metal dichalcogenide family of 2D semiconductors. We calculate accurate relaxations for MoS2 even at small twist-angle values, enabled by the fact that our approach does not rely on empirical atomistic potentials for interlayer coupling. The results demonstrate the ef?ciency of the con?guration space method by computing relaxations with minimal computational cost. We also outline a general explanation of domain formation in 2D bilayers with nearly aligned lattices, taking advantage of the relationship between real space and con?guration space. The con?guration space approach also enables calculation of relaxations in incommensurate multilayer systems.
关键词： incommensurate,domain formation,MoS2,bilayers,two-dimensional,relaxation,graphene
更新于2025-09-09 09:28:46
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Investigation of the microstructural, surface and optical properties of nano-layer MoxSy thin film deposited by thermionic vacuum arc
摘要： Molybdenum disulfide (MoxSy) thin film was deposited onto the glass substrate using Thermionic Vacuum Arc (TVA) technique. MoS2 as know as low-friction coefficient and solid lubricant material and it is a 2-dimension material. In this study, properties of the 2D (MoxSy) were determined. In 2D coating, mixed phase of MoS2, Mo2S3, Mo3S4 and Mo15S19 crystal reflection planes were detected in XRD pattern. The thickness of the film was measured as to be 30 nm. The crystallite sizes were calculated in the range of 6-20 nm. deposited 2D layer is nearly equal to about 1.98 eV. The dielectric constant for the deposited layer is very close to 4.3. To determine the optical impurity and defects, photoluminescence and Raman analyses were done. Also, friction coefficient of the 2D nano layer was measured by ball on disk technique.
关键词： optical properties,microstructural properties,MoS2 thin film,TVA
更新于2025-09-09 09:28:46
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Improved Electrical Contact Properties of MoS <sub/>2</sub> -Graphene Lateral Heterostructure
摘要： 2D materials have been extensively investigated in view of their excellent electrical/optical properties, with particular attention directed at the fabrication of vertical or lateral heterostructures. Although such heterostructures exhibit unexpected or enhanced properties compared to those of singly used 2D materials, their fabrication is challenged by the difficulty of realizing spatial control and large area integration. Herein, MoS2 is grown on patterned graphene at variable temperatures, combining the concept of lateral heterostructure with chemical vapor deposition to realize large area growth with precise spatial control, and probe the spatial distribution of graphene and MoS2 by a number of instrumental techniques. The prepared MoS2-graphene lateral heterostructure is employed to construct field effect transistors with graphene as the source/drain and MoS2 as the channel, and the performance of these transistors (on/off ratio ≈109, maximum field effect mobility = 8.5 cm2 V?1 s?1) is shown to exceed that of their MoS2-only counterparts.
关键词： chemical vapor deposition,lateral,heterostructure,contact resistance,MoS2,graphene
更新于2025-09-04 15:30:14
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Element- and Site-Specific Many-Body Interactions in Few-Layer MoS <sub/>2</sub> During X-Ray Absorption Processes
摘要： Few-layer MoS2 is a promising 2D material for nano-electronic device applications. However, the performance of these devices is often deteriorated. One of the reasons is that the electronic properties are influential to the many-body effects such as excitonic effects and Anderson orthogonality catastrophe (AOC) which could renormalize the band-dispersion and density-of-states(DOS). Hence, the authors investigate the effect of many-body interactions on MoS2 device performance by using X-ray absorption spectro-microscopy (m-XAS) on a few-layer MoS2 transistor in operation, through the application of gate-bias or contact with a metal. The results show a significant peak shift in m-XAS spectra while varying the gate-bias. The applied negative gate-bias induces more holes which attracts excited electrons resulting strong many-body interactions followed by Fermi level shift. This effect is discussed with the aid of XAS-Auger electron phenomena. However, the AOC contribution in XAS peak-intensity is ignored since the bands around the energy-gap in MoS2 are relatively flat and the DOS is empty above Fermi level (unlike graphene). The authors observe a redshift in photon energy near the MoS2/metal-electrode interface due to charge transfer ensuring carrier-doping induced through metal-contact. These observations provide significant insight into element- and site-specific many-body interactions in MoS2 tunable by gate-bias or contact with a metal.
关键词： many-body interactions,element- and site-specific,MoS2,X-ray absorption spectromicroscopy
更新于2025-09-04 15:30:14
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Large enhancement of infrared absorption due to trimer comprised of doping-N and S-S divacancies in the imperfect monolayer MoS2: A first-principles study
摘要： In this study, we systematically study on crystal and electronic structures and optical absorption properties of perfect monolayer MoS2 (M), M with S vacancy (M@SV), M with N doping at S site (M@ND) and M with both S vacancy and N doping at S site (M@V-D) using first-principles method. It is showed that the N atom is tend to located between Mo and S layers, leaving one vacancy at original site, to form interstitial N atom. Thus, the interstitial N atom and the S vacancy make up the NI-VS dimer. We study M@V-D with five atomic configurations and find the most stable structure having the NI-VS-VS trimer. It is showed that the absorbance for the stable M@V-D in the most infrared region is obviously higher than that for the other systems. It is revealed that large enhancement of infrared absorption for the stable M@V-D is mainly attributable to the special electronic structure determined by the crystal structure with the trimer. It is considered that M@V-D could be the promising candidate for infrared materials.
关键词： Monolayer MoS2,Infrared absorption
更新于2025-09-04 15:30:14
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Low-Temperature Process for Direct Formation of MoS2 Thin Films on Soda-Lime Glass Substrates
摘要： To obtain molybdenum disulfide (MoS2) patterns without any mechanical problems caused by the transfer process, direct current (DC) sputtering and rapid thermal processing (RTP) were used to form MoS2 instead of the conventional chemical vapor deposition (CVD) process. To form MoS2 on a soda-lime glass substrate at temperatures below 600 °C, MoS2 films were deposited at various DC sputtering powers and annealed at various temperatures from 400 °C to 550 °C. From the scanning electron microscope (SEM) and atomic force microscope (AFM) results, the surface morphologies of the MoS2 films can be observed, depending on the sputtering power and the film thickness. The Raman spectrum results showed that the E1 2g and A1 g mode peaks appeared at approximately 372 cm?1 and 400 cm?1, respectively, and the MoS2 surface was crystallized in the in-plane direction. The X-ray photoelectron spectroscopy (XPS) results showed noticeable S 2p (2p 1/2, 2p 3/2) peaks and Mo 3d (3d 3/2, 3d 5/2) peaks at stable binding energies after RTP at temperatures below 600 °C. The high mobilities and carrier densities of all the MoS2 films can be investigated from the Hall measurements.
关键词： DC Sputtering,Low Temperature,Molybdenum Disulfide (MoS2),Rapid Thermal Processing (RTP),Soda-Lime Glass
更新于2025-09-04 15:30:14