Here, it is first reported that a self‐powered photodetector based on a MoS2/CH3NH3PbI3 vertical type heterojunction, which has responsivity of 60 mAW−1 and response/recovery time of 2149/899 ms. Under bias, it exhibits a photoswitching ratio exceeding 1522, fast response/recovery time of 205/206 ms, and high photoresponsivity of 68.11 AW−1. The optoelectronic performances of the photodetector are closely related to the type of the MoS2/CH3NH3PbI3 heterojunction, which acts as a hole (electron) transport field and can effectively decrease the recombination of holes and electrons. Additionally, the MoS2/CH3NH3PbI3 planar type heterojunction is also built to compare with the vertical type in optoelectronics behavior. Due to the existence of internal field, the properties of vertical type photodetector are better than those of the planar type which also presents good performance with on/off ratio up to 1476, photoresponsivity of 28 AW−1, and response rate of 356/204 ms. These results pave a new way to form an ultrahigh performance MoS2/CH3NH3PbI3 heterojunction, hold the promise for construction of a self‐powered photodetector, and develop promising atomically thin MoS2 heterostructure device for photovoltaic and optoelectronic applications. 相似文献
In this letter, the vertically‐stacked GaSe/MoS2 heterostructures with indium tin oxide (ITO) and Ni/Au as contact electrodes are successfully fabricated, respectively. The GaSe/MoS2 heterostructure exhibits a broadband photoresponse covering the range of visible to near‐infrared spectra at room temperature without external bias voltage. When ITO serves as contact electrodes, a high rectification ratio, i.e., 1.5 × 104 at VDS = ±1 V, and an excellent photoelectric performance, i.e., responsivity of ≈0.67 A W‐1, specific detectivity of ≈2.3 × 1011 cm Hz1/2 W‐1 and external quantum efficiency of ≈160% at the wavelength of 520 nm is achieved. Moreover, the GaSe/MoS2 heterostructure with Ohmic‐contact ITO electrodes demonstrates a faster response time of 155 µs, which is 4 times faster than the GaSe/MoS2 heterostructure with Ni/Au electrodes and about 300 times faster than previous reports. These results reveal the presence of an abrupt p–n junction between GaSe and MoS2 and significant role of electrode‐contact mode in determining the photoelectric properties of GaSe/MoS2 heterostructure. 相似文献
Layered van der Waals heterostructures have attracted considerable attention recently, due to their unique properties both inherited from individual two‐dimensional (2D) components and imparted from their interactions. Here, a novel few‐layer MoS2/glassy‐graphene heterostructure, synthesized by a layer‐by‐layer transfer technique, and its application as transparent photodetectors are reported for the first time. Instead of a traditional Schottky junction, coherent ohmic contact is formed at the interface between the MoS2 and the glassy‐graphene nanosheets. The device exhibits pronounced wavelength selectivity as illuminated by monochromatic lights. A responsivity of 12.3 mA W?1 and detectivity of 1.8 × 1010 Jones are obtained from the photodetector under 532 nm light illumination. Density functional theory calculations reveal the impact of specific carbon atomic arrangement in the glassy‐graphene on the electronic band structure. It is demonstrated that the band alignment of the layered heterostructures can be manipulated by lattice engineering of 2D nanosheets to enhance optoelectronic performance. 相似文献
The important role of p–n junction in modulation of the optoelectronic properties of semiconductors is widely cognized. In this work, for the first time the synthesis of p‐GaSe/n‐MoS2 heterostructures via van der Waals expitaxial growth is reported, although a considerable lattice mismatching of ≈18% exists. According to the simulation, a significant type II p–n junction barrier located at the interface is expected to be formed, which can modulate optoelectronic properties of MoS2 effectively. It is intriguing to reveal that the presence of GaSe can result in obvious Raman and photoluminescence (PL) shift of MoS2 compared to that of pristine one, more interestingly, for PL peak shift, the effect of GaSe‐induced tensile strain on MoS2 has overcome the p‐doping effect of GaSe, evidencing the strong interlayer coupling between GaSe and MoS2. As a result, the photoresponse rate of heterostructures is improved by almost three orders of magnitude compared with that of pristine MoS2. 相似文献
FeS2‐sensitized ZnO@ZnS nanorod arrays are fabricated by a two‐step solution immersion and a subsequent sulfurization. The material properties including structure, morphology, and photoluminescence are investigated by a variety of characterization methods. As compared with ZnO@ZnS core/shell structure, FeS2‐sensitized ZnO@ZnS nanorod arrays show improved optical absorption property with the extension of the absorption edge into the range of visible light. The photoresponse performance of FeS2‐sensitized Zno@ZnS is also enhanced as the photocurrent density at 1.0 V is dozens of times larger than that of ZnO@ZnS nanorods. The cause for the difference in such material properties of these two materials is discussed. In this work, a new method for sensitizing wide bandgap ZnO@ZnS nanorod arrays with improved light response performance is presented. 相似文献
The residue of common photo‐ and electron‐beam resists, such as poly(methyl methacrylate) (PMMA), is often present on the surface of 2D crystals after device fabrication. The residue degrades device properties by decreasing carrier mobility and creating unwanted doping. Here, MoS2 and WSe2 field effect transistors (FETs) with residue are cleaned by contact mode atomic force microscopy (AFM) and the impact of the residue on: 1) the intrinsic electrical properties, and 2) the effectiveness of electric double layer (EDL) gating are measured. After cleaning, AFM measurements confirm that the surface roughness decreases to its intrinsic state (i.e., ≈0.23 nm for exfoliated MoS2 and WSe2) and Raman spectroscopy shows that the characteristic peak intensities (E2g and A1g) increase. PMMA residue causes p‐type doping corresponding to a charge density of ≈7 × 1011 cm−2 on back‐gated MoS2 and WSe2 FETs. For FETs gated with polyethylene oxide (PEO)76:CsClO4, removing the residue increases the charge density by 4.5 × 1012 cm−2, and the maximum drain current by 247% (statistically significant, p < 0.05). Removing the residue likely allows the ions to be positioned closer to the channel surface, which is essential for achieving the best possible electrostatic gate control in ion‐gated devices. 相似文献
The heterostructure of 2D material with different orientations and TiO2 has been proven to be a good candidate for photocatalytic water splitting. However, the detailed mechanism of the orientation of 2D materials with TiO2 has not been explored. Herein, different combinations of edge‐on MoS2 or basal‐on MoS2 with TiO2 are investigated systematically. The adsorption energy, the activation energy barrier, as well as the charge distribution reveal that edge‐on heterostructures have better efficiency in the separation of photoelectron–hole pairs and can enhance the efficiency of hydrogen evolution reaction. This work studies the differences in mechanisms of edge‐on and basal‐on heterostructures in hydrogen evolution reactions. The simulated results provide significant theoretical foundation for the design of new materials. 相似文献
A demonstration is presented of how significant improvements in all‐2D photodetectors can be achieved by exploiting the type‐II band alignment of vertically stacked WS2/MoS2 semiconducting heterobilayers and finite density of states of graphene electrodes. The photoresponsivity of WS2/MoS2 heterobilayer devices is increased by more than an order of magnitude compared to homobilayer devices and two orders of magnitude compared to monolayer devices of WS2 and MoS2, reaching 103 A W?1 under an illumination power density of 1.7 × 102 mW cm?2. The massive improvement in performance is due to the strong Coulomb interaction between WS2 and MoS2 layers. The efficient charge transfer at the WS2/MoS2 heterointerface and long trapping time of photogenerated charges contribute to the observed large photoconductive gain of ≈3 × 104. Laterally spaced graphene electrodes with vertically stacked 2D van der Waals heterostructures are employed for making high‐performing ultrathin photodetectors. 相似文献
2D semiconductors have shown great potential for application to electrically tunable optoelectronics. Despite the strong excitonic photoluminescence (PL) of monolayer transition metal dichalcogenides (TMDs), their efficient electroluminescence (EL) has not been achieved due to the low efficiency of charge injection and electron–hole recombination. Here, multioperation-mode light-emitting field-effect transistors (LEFETs) consisting of a monolayer WSe2 channel and graphene contacts coupled with two top gates for selective and balanced injection of charge carriers are demonstrated. Visibly observable EL is achieved with the high external quantum efficiency of ≈6% at room temperature due to efficient recombination of injected electrons and holes in a confined 2D channel. Further, electrical tunability of both the channel and contacts enables multioperation modes, such as antiambipolar, depletion,and unipolar regions, which can be utilized for polarity-tunable field-effect transistors and photodetectors. The work exhibits great potential for use in 2D semiconductor LEFETs for novel optoelectronics capable of high efficiency, multifunctions, and heterointegration. 相似文献
Large area MoS2 films with tunable physical‐chemical properties are grown on dielectric substrates by annealing of ultrathin Mo layers in the presence of a sulfur‐containing gaseous precursor. Different growth conditions are found to have a significant impact on material properties, including chemical composition, roughness, and grain sizes, thus shedding light on critical parameters that govern sulfurization processes for the synthesis of large area 2D transition metal dichalcogenides. Optimized growth conditions in combination with the use of single crystal sapphire substrates with atomically flat interface result in the formation of oriented MoS2 films with improved quality and electrical performance. On the basis of this versatile synthesis technique, an original double‐step process is presented for the synthesis of WS2/MoS2 vertical heterostructures. Good uniformity of layers over large area has enabled first isolation of defects by electron spin resonance spectroscopy with densities correlated with mobility degradation and the first experimental characterization of the band alignment at the interfaces of MoS2, WS2, and their vertical stacks with the underlying SiO2 insulator. 相似文献
Typically, molybdenum disulfide (MoS2) synthesized by chemical vapor deposition (CVD) is polycrystalline; as a result, the scattering of charge carriers at grain boundaries can lead to performances lower than those observed in exfoliated single-crystal MoS2. Until now, the electrical properties of grain boundaries have been indirectly studied without accurate knowledge of their location. Here, we present a technique to measure the electrical behavior of individual grain boundaries in CVD-grown MoS2, imaged with the help of aligned liquid crystals. Unexpectedly, the electrical conductance decreased by three orders of magnitude for the grain boundaries with the lowest on/off ratio. Our study provides a useful technique to fabricate devices on a single-crystal area, using optimized growth conditions and device geometry. The photoresponse, studied within a MoS2 single grain, showed that the device responsivity was comparable with that of the exfoliated MoS2-based photodetectors.
Constructing 2D heterostructure materials by stacking different 2D materials can combine the merits of the individual building blocks while eliminating their shortcomings. Dichalcogenides are attractive anodes for potassium-ion batteries (KIBs) due to their high theoretical capacity. However, the practical application of dichalcogenide is greatly hampered by the poor electrochemical performance due to sluggish kinetics of K+ insertion and the electrode structure collapse resulting from the large K+ insertion. Herein, heterostructures of 2D molybdenum dichalcogenide on 2D nitrogen-doped carbon (MoS2, MoSe2-on-NC) are prepared to boost their potassium storage performance. The unique 2D heterostructures possess built-in heterointerfaces, facilitating K+ diffusion. The robust chemical bonds (C S, C Se, C Mo bonds) enhance the mechanical strength of electrodes, thus suppressing the volume expansion. The 2D N-doped carbon nanosheets interconnected as a 3D structure offer a fast diffusion path for electrons. Benefitting from these merits, both the MoS2-on-NC and the MoSe2-on-NC exhibit unprecedented cycle life. Moreover, the electrochemical reaction mechanism of MoSe2 is revealed during the process of potassiation and depotassiation. 相似文献
Herein, the structure of integrated M3D inverters are successfully demonstrated where a chemical vapor deposition (CVD) synthesized monolayer WSe2 p-type nanosheet FET is vertically integrated on top of CVD synthesized monolayer MoS2 n-type film FET arrays (2.5 × 2.5 cm) by semiconductor industry techniques, such as transfer, e-beam evaporation (EBV), and plasma etching processes. A low temperature (below 250 °C) is employed to protect the WSe2 and MoS2 channel materials from thermal decomposition during the whole fabrication process. The MoS2 NMOS and WSe2 PMOS device fabricated show an on/off current ratio exceeding 106 and the integrated M3D inverters indicate an average voltage gain of ≈9 at VDD = 2 V. In addition, the integrated M3D inverter demonstrates an ultra-low power consumption of 0.112 nW at a VDD of 1 V. Statistical analysis of the fabricated inverters devices shows their high reliability, rendering them suitable for large-area applications. The successful demonstration of M3D inverters based on large-scale 2D monolayer TMDs indicate their high potential for advancing the application of 2D TMDs in future integrated circuits. 相似文献
van der Waals (vdW) heterostructures based on atomically thin 2D materials have led to a new era in next‐generation optoelectronics due to their tailored energy band alignments and ultrathin morphological features, especially in photodetectors. However, these photodetectors often show an inevitable compromise between photodetectivity and photoresponsivity with one high and the other low. Herein, a highly sensitive WSe2/SnS2 photodiode is constructed on BN thin film by exfoliating each material and manually stacking them. The WSe2/SnS2 vdW heterostructure shows ultralow dark currents resulting from the depletion region at the junction and high direct tunneling current when illuminated, which is confirmed by the energy band structures and electrical characteristics fitted with direct tunneling. Thus, the distinctive WSe2/SnS2 vdW heterostructure exhibits both ultrahigh photodetectivity of 1.29 × 1013 Jones (Iph/Idark ratio of ≈106) and photoresponsivity of 244 A W?1 at a reverse bias under the illumination of 550 nm light (3.77 mW cm?2). 相似文献
Violet phosphorus (VP), a newly emerging elemental 2D semiconductor, with attractive properties such as tunable bandgap, high carrier mobility, and unusual structural anisotropy, offers significant opportunities for designing high-performance electronic and optoelectronic devices. However, the study on fundamental property and device application of 2D VP is seriously hindered by its inherent instability in ambient air. Here, a VP/MoS2 van der Waals heterostructure is constructed by vertically staking few-layer VP and MoS2, aiming to utilize the synergistic effect of the two materials to achieve a high-performance 2D photodetector. The strong optical absorption of VP combining with the type-II band alignment of VP/MoS2 heterostructure make VP play a prominent photogating effect. As a result, the VP/MoS2 heterostructure photodetector achieves an excellent photoresponse performances with ultrahigh responsivity of 3.82 × 105 A W–1, high specific detectivity of 9.17 × 1013 Jones, large external quantum efficiency of 8.91 × 107 %, and gate tunability, which are much superior to that of individual MoS2 device or VP device. Moreover, the VP/MoS2 heterostructure photodetector indicates superior air stability due to the effective protection of VP by MoS2 encapsulation. This work sheds light on the future study of the fundamental property and optoelectronic device application of VP. 相似文献
Simple stacking of thin van der Waals 2D materials with different physical properties enables one to create heterojunctions (HJs) with novel functionalities and new potential applications. Here, a 2D material p–n HJ of GeSe/MoS2 is fabricated and its vertical and horizontal carrier transport and photoresponse properties are studied. Substantial rectification with a very high contrast (>104) through the potential barrier in the vertical‐direction tunneling of HJs is observed. The negative differential transconductance with high peak‐to‐valley ratio (>105) due to the series resistance change of GeSe, MoS2, and HJs at different gate voltages is observed. Moreover, strong and broad‐band photoresponse via the photoconductive effect are also demonstrated. The explored multifunctional properties of the GeSe/MoS2 HJs are expected to be important for understanding the carrier transport and photoresponse of 2D‐material HJs for achieving their use in various new applications in the electronics and optoelectronics fields. 相似文献
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