The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising c...The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising candidates due to their built-in electric fields,ultrafast photocarrier separation,and tunable bandgaps,defect states limit their performance.Therefore,the modulation of the optoelectronic properties in such heterostructures is imperative.Surface charge transfer doping(SCTD)has emerged as a promising strategy for non-destructive modulation of electronic and optoelectronic characteristics in two-dimensional materials.In this work,we demonstrate the construction of high-performance p-i-n vertical heterojunction photodetectors through SCTD of MoTe_(2)/ReS_(2)heterostructure using p-type F_(4)-TCNQ.Systematic characterization reveals that the interfacial doping process effectively amplifies the built-in electric field,enhancing photogenerated carrier separation efficiency.Compared to the pristine heterojunction device,the doped photodetector exhibits remarkable visible to nearinfrared(635-1064 nm)performance.Particularly under 1064 nm illumination at zero bias,the device achieves a responsivity of 2.86 A/W and specific detectivity of 1.41×10^(12)Jones.Notably,the external quantum efficiency reaches an exceptional value of 334%compared to the initial 11.5%,while maintaining ultrafast response characteristics with rise/fall times of 11.6/15.6μs.This work provides new insights into interface engineering through molecular doping for developing high-performance vd W optoelectronic devices.展开更多
The two-dimensional(2D)material-based thermal switch is attracting attention due to its novel applications,such as energy conversion and thermal management,in nanoscale devices.In this paper,we observed that the rever...The two-dimensional(2D)material-based thermal switch is attracting attention due to its novel applications,such as energy conversion and thermal management,in nanoscale devices.In this paper,we observed that the reversible 2H–1T′phase transition in MoTe_(2)is associated with about a fourfold/tenfold change in thermal conductivity along the X/Y direction by using first-principles calculations.This phenomenon can be profoundly understood by comparing the Mo–Te bonding strength between the two phases.The 2H-MoTe_(2)has one stronger bonding type,while 1T′-MoTe_(2)has three weaker types of bonds,suggesting bonding inhomogeneity in 1T′-MoTe_(2).Meanwhile,the bonding inhomogeneity can induce more scattering of vibration modes.The weaker bonding indicates a softer structure,resulting in lower phonon group velocity,a shorter phonon relaxation lifetime and larger Gr¨uneisen constants.The impact caused by the 2H to 1T′phase transition in MoTe_(2)hinders the propagation of phonons,thereby reducing thermal conductivity.Our study describes the possibility for the provision of the MoTe_(2)-based controllable and reversible thermal switch device.展开更多
The direct synthesis of hydrogen peroxide(H_(2)O_(2))via a two‐electron oxygen reduction reaction(2e‐ORR)in acidic media has emerged as a green process for the production of this valuable chemical.However,such an ap...The direct synthesis of hydrogen peroxide(H_(2)O_(2))via a two‐electron oxygen reduction reaction(2e‐ORR)in acidic media has emerged as a green process for the production of this valuable chemical.However,such an approach employs expensive noble‐metal‐based electrocatalysts,which severely undermines its feasibility when implemented on an industrial scale.Herein,based on density functional theory computations and microkinetic modeling,we demonstrate that a novel two‐dimensional(2D)material,namely a 1T′‐MoTe_(2)monolayer,can serve as an efficient non‐precious electrocatalyst to facilitate the 2e‐ORR.The 1T′‐MoTe_(2)monolayer is a stable 2D crystal that can be easily produced through exfoliation techniques.The surface‐exposed Te sites of the 1T′‐MoTe_(2)monolayer exhibit a favorable OOH*binding energy of 4.24 eV,resulting in a rather high basal plane activity toward the 2e‐ORR.Importantly,kinetic computations indicate that the 1T'‐MoTe_(2)monolayer preferentially promotes the formation of H_(2)O_(2)over the competing four‐electron ORR step.These desirable characteristics render 1T′‐MoTe_(2)a promising candidate for catalyzing the electrochemical reduction of O_(2)to H_(2)O_(2).展开更多
Two-dimensional(2D)MoTe_(2) shows great potential for future semiconductor devices,but the lab-to-fab transition is still in its preliminary stage due to the constraints in the crystal growth level.Currently,the chemi...Two-dimensional(2D)MoTe_(2) shows great potential for future semiconductor devices,but the lab-to-fab transition is still in its preliminary stage due to the constraints in the crystal growth level.Currently,the chemical vapor deposition growth of 2D MoTe_(2) primarily relies on the tellurization process of Mo-source precursor(MSP).However,the target product 2H-MoTe_(2) from Mo precursor suffers from long growth time and suboptimal crystal quality,and MoO_(x) precursor confronts the dilemma of unclear growth mechanism and inconsistent growth products.Here,we developed magnetron-sputtered MoO_(3) film for fast and high-mobility 2H-MoTe_(2) growth.The solid-to-solid phase transition growth mechanism of 2D MoTe_(2) from Mo and MoO_(x) precursor was first experimentally unified,and the effect mechanism of MSPs on 2D MoTe_(2) growth was systematically elucidated.Compared with Mo and MoO2,the MoO_(3) precursor has the least Mo-unit lattice deformation and exhibits the optimal crystal quality of growth products.Meanwhile,the lowest Gibbs free energy change of the chemical reaction results in an impressive 2HMoTe_(2) growth rate of 8.07 mm/min.The constructed 2H-MoTe_(2) field-effect transistor array from MoO_(3) precursor showcases record-high hole mobility of 85 cm^(2)·V^(-1)·s^(-1),competitive on-off ratio of 3×10^(4),and outstanding uniformity.This scalable method not only offers efficiency but also aligns with industry standards,making it a promising guideline for diverse 2D material preparation towards real-world applications.展开更多
Two-dimensional(2D)semiconductor-based junction field-effect transistors(JFETs)have emerged as vital architectures for next-generation low-power electronics due to their gate-dielectric-free structure and near-ideal s...Two-dimensional(2D)semiconductor-based junction field-effect transistors(JFETs)have emerged as vital architectures for next-generation low-power electronics due to their gate-dielectric-free structure and near-ideal subthreshold swing(SS)potential.Although doping strategies,such as defect engineering and chemical modification,can further enhance the performance of JFETs,complex techniques and uniformly-doping hinder their further applications.Here,we propose a lowpower MoS_(2)/MoTe_(2) JFET utilizing a pre-deposited Au film to dope the gate layer of MoTe_(2),which can uniformly increase the work function of MoTe_(2) and thus elevate heterostructure barrier heights.This method offers strong repeatability,avoids localized states on channel material,and is compatible with integrated circuit manufacturing.The JFETs achieve a near-ideal SS of 62.5 mV dec−1,mobility of 350 cm2 V−1 s−1,high current on/off ratio of 107,low gate leakage of 10−12 A,and low pinch-off voltage of−0.1 V.This strategy provides a universal and simple strategy for low-power circuits.展开更多
Two-dimensional(2D)materials hold immense potential for next-generation information devices due to their ambipolar transport and tunable electronic states.However,conventional electric-field-driven architectures suffe...Two-dimensional(2D)materials hold immense potential for next-generation information devices due to their ambipolar transport and tunable electronic states.However,conventional electric-field-driven architectures suffer from inherent carrier-type degeneracy:Electrons and holes generate unidirectional currents,leading to ambiguous state overlaps in multi-level operation.Here,we demonstrate that surface acoustic waves(SAWs)break this symmetry in optically reconfigurable MoTe_(2)/h-BN heterostructures.SAWs induce type-II band modulation in the heterostructure and spatially separate electrons and holes into distinct valleys,enabling bidirectional acoustoelectric currents,whose polarity reverses with carrier type,controlled dynamically via ultraviolet(UV)illumination and gating.Leveraging this mechanism,we realize an 8-state memory device where SAW-driven readout currents changed between positive and negative polarities,achieving enhanced inter-state differentiation compared to voltage-read schemes.For synaptic applications,SAW-driven weight updates in n-and p-type regimes produce anti-symmetric conductance trajectories,eliminating state collisions observed in electric-field-driven counterparts.This work pioneers acoustic wave manipulation of ambipolar transport,offering transformative strategies for degeneracy-free,high-precision neuromorphic electronics.展开更多
The realization of controllable polarity photoresponse within a single device is a crucial advancement for simulating biological bipolar vision cells to drive the development of next-generation optoelectronic technolo...The realization of controllable polarity photoresponse within a single device is a crucial advancement for simulating biological bipolar vision cells to drive the development of next-generation optoelectronic technologies.Nevertheless,current polarity photodetectors face significant challenges in fully suppressing symmetric photocurrent cancellation and optimizing carrier transport efficiency.Here,we propose a graphene-intercalated MoS_(2)/MoTe_(2)heterojunction,featuring a tailorable built-in electric field and a high efficiency transport channel.Spatially resolved photocurrent reveals that the controllable polarity photoresponse originates from the bias-dependent equivalent built-in electric field of MoS_(2)/MLG/MoTe_(2)heterojunction.The controllable polarity photoresponse realizes a large-area uniform“heart-shaped”photocurrent region.In enhanced polarity photoresponse mode,the photodetector exhibits broadband detection capabilities from visible(638 nm)to infrared(1550 nm)light,achieving a high responsivity of 18.1 A/W and an excellent detectivity of 2.8×10^(12)Jones,as well as fast response times of 94/119μs.Furthermore,precise imaging with a resolution better than 0.5 mm was successfully demonstrated,highlighting its polarity photoresponse for practical imaging applications.This work provides a new paradigm for controllable polarity photoresponse programmed by intercalated low-dimensional material structures,paving the way for next-generation intelligent sensing chips.展开更多
Phase transition and edge structure reconstruction of twodimensional(2D)materials are critical for modulating their properties and applications.Here,we employ a hydrogen-assisted annealing method to accomplish the ext...Phase transition and edge structure reconstruction of twodimensional(2D)materials are critical for modulating their properties and applications.Here,we employ a hydrogen-assisted annealing method to accomplish the extensive transformation from a 2H MoTe_(2)single crystal to Mo_(6)Te_(6)nanowires and quasi-2D Mo_(6)Te_(6)nanoribbons.Introducing hydrogen gas during atmospheric pressure annealing process generates a Te-poor chemical environment,which makes the transformations energetically favorable and is essential for the fast growth of Mo_(6)Te_(6)nanowires.Mo_(6)Te_(6)nanowires nucleate at the exposed edges of 2H MoTe_(2)and grow along its[1120],[2110],and[1210]crystallographic directions,demonstrating long-range order and forming quais-2D nanoribbons with lengths up to 50μm.Finally,nanoribbons align in sixfold oriented directions and form an array within 3 mm^(2)area on SiO_(2)/Si substrate.Mo_(6)Te_(6)nanowires display metallic behavior and have large charge transfer with Rhodamine 6G,making them excellent substrates for surface-enhanced Raman scattering.It shows a low detectable concentration of 10^(-13)mol/L for Rhodamine 6G and a Raman enhancement factor of 7×10^(8).Our findings provide an economic and efficient synthesis method for producing sixfold-oriented Mo_(6)Te_(6)nanowires and nanoribbons networks,which can serve as platform for exploring lowdimensional physical properties,designing electronic devices,and applications in analytical chemistry.展开更多
基金financial support from 2024 Domestic Visiting Scholar Program for Teachers'Professional Development in Universities(Grant No.FX2024022)National Natural Science Foundation of China(Grant No.61904043)。
文摘The development of optoelectronic technologies demands photodetectors with miniaturization,broadband operation,high sensitivity,and low power consumption.Although 2D van der Waals(vd W)heterostructures are promising candidates due to their built-in electric fields,ultrafast photocarrier separation,and tunable bandgaps,defect states limit their performance.Therefore,the modulation of the optoelectronic properties in such heterostructures is imperative.Surface charge transfer doping(SCTD)has emerged as a promising strategy for non-destructive modulation of electronic and optoelectronic characteristics in two-dimensional materials.In this work,we demonstrate the construction of high-performance p-i-n vertical heterojunction photodetectors through SCTD of MoTe_(2)/ReS_(2)heterostructure using p-type F_(4)-TCNQ.Systematic characterization reveals that the interfacial doping process effectively amplifies the built-in electric field,enhancing photogenerated carrier separation efficiency.Compared to the pristine heterojunction device,the doped photodetector exhibits remarkable visible to nearinfrared(635-1064 nm)performance.Particularly under 1064 nm illumination at zero bias,the device achieves a responsivity of 2.86 A/W and specific detectivity of 1.41×10^(12)Jones.Notably,the external quantum efficiency reaches an exceptional value of 334%compared to the initial 11.5%,while maintaining ultrafast response characteristics with rise/fall times of 11.6/15.6μs.This work provides new insights into interface engineering through molecular doping for developing high-performance vd W optoelectronic devices.
基金the China Scholarship Council(Grant No.202107000030)RIE2020 Advanced Manufacturing and Engineering(AME)Programmatic(Grant No.A1898b0043)A*STAR Aerospace Programme(Grant No.M2115a0092)。
文摘The two-dimensional(2D)material-based thermal switch is attracting attention due to its novel applications,such as energy conversion and thermal management,in nanoscale devices.In this paper,we observed that the reversible 2H–1T′phase transition in MoTe_(2)is associated with about a fourfold/tenfold change in thermal conductivity along the X/Y direction by using first-principles calculations.This phenomenon can be profoundly understood by comparing the Mo–Te bonding strength between the two phases.The 2H-MoTe_(2)has one stronger bonding type,while 1T′-MoTe_(2)has three weaker types of bonds,suggesting bonding inhomogeneity in 1T′-MoTe_(2).Meanwhile,the bonding inhomogeneity can induce more scattering of vibration modes.The weaker bonding indicates a softer structure,resulting in lower phonon group velocity,a shorter phonon relaxation lifetime and larger Gr¨uneisen constants.The impact caused by the 2H to 1T′phase transition in MoTe_(2)hinders the propagation of phonons,thereby reducing thermal conductivity.Our study describes the possibility for the provision of the MoTe_(2)-based controllable and reversible thermal switch device.
文摘The direct synthesis of hydrogen peroxide(H_(2)O_(2))via a two‐electron oxygen reduction reaction(2e‐ORR)in acidic media has emerged as a green process for the production of this valuable chemical.However,such an approach employs expensive noble‐metal‐based electrocatalysts,which severely undermines its feasibility when implemented on an industrial scale.Herein,based on density functional theory computations and microkinetic modeling,we demonstrate that a novel two‐dimensional(2D)material,namely a 1T′‐MoTe_(2)monolayer,can serve as an efficient non‐precious electrocatalyst to facilitate the 2e‐ORR.The 1T′‐MoTe_(2)monolayer is a stable 2D crystal that can be easily produced through exfoliation techniques.The surface‐exposed Te sites of the 1T′‐MoTe_(2)monolayer exhibit a favorable OOH*binding energy of 4.24 eV,resulting in a rather high basal plane activity toward the 2e‐ORR.Importantly,kinetic computations indicate that the 1T'‐MoTe_(2)monolayer preferentially promotes the formation of H_(2)O_(2)over the competing four‐electron ORR step.These desirable characteristics render 1T′‐MoTe_(2)a promising candidate for catalyzing the electrochemical reduction of O_(2)to H_(2)O_(2).
基金supported by the National Natural Science Foundation of China(Grant Nos.51991340,51991342,52225206,92163205,52188101,62322402,52350301,62204012,52250398,52303362,62304019)the National Key Research and Development Program of China(Grant No.2022YFA1203800,2022YFA1203803,2018YFA0703503,2023YFF1500400,2023YFF1500401)+7 种基金the Overseas Expertise Introduction Projects for Discipline Innovation(Grant No.B14003)the Frontier Cross Research Project of the Department of Chinese Academy of Sciences(Grant No.XK2023JSA001)the Beijing Nova Program(Grant No.20220484145,20230484478)the Young Elite Scientists sponsorship program by CAST(Grant No.2022QNRC001)the Fundamental Research Funds for the Central Universities(Grant No.FRF-06500207,FRF-TP-22-004C2,FRF-06500207,FRF-TP-22-004A1,FRF-IDRY-22-016)the State Key Lab for Advanced Metals andMaterials (No. 2023-Z05)Postdoctoral Fellowship Program of CPSF(GZC20230233)the Special support from the PostdoctoralScience Foundation (2023TQ0007).
文摘Two-dimensional(2D)MoTe_(2) shows great potential for future semiconductor devices,but the lab-to-fab transition is still in its preliminary stage due to the constraints in the crystal growth level.Currently,the chemical vapor deposition growth of 2D MoTe_(2) primarily relies on the tellurization process of Mo-source precursor(MSP).However,the target product 2H-MoTe_(2) from Mo precursor suffers from long growth time and suboptimal crystal quality,and MoO_(x) precursor confronts the dilemma of unclear growth mechanism and inconsistent growth products.Here,we developed magnetron-sputtered MoO_(3) film for fast and high-mobility 2H-MoTe_(2) growth.The solid-to-solid phase transition growth mechanism of 2D MoTe_(2) from Mo and MoO_(x) precursor was first experimentally unified,and the effect mechanism of MSPs on 2D MoTe_(2) growth was systematically elucidated.Compared with Mo and MoO2,the MoO_(3) precursor has the least Mo-unit lattice deformation and exhibits the optimal crystal quality of growth products.Meanwhile,the lowest Gibbs free energy change of the chemical reaction results in an impressive 2HMoTe_(2) growth rate of 8.07 mm/min.The constructed 2H-MoTe_(2) field-effect transistor array from MoO_(3) precursor showcases record-high hole mobility of 85 cm^(2)·V^(-1)·s^(-1),competitive on-off ratio of 3×10^(4),and outstanding uniformity.This scalable method not only offers efficiency but also aligns with industry standards,making it a promising guideline for diverse 2D material preparation towards real-world applications.
基金supported by the National Natural Science Foundation of China(52350301,52250398,92463308,62322402,52188101,52225206,92163205,62204012,52303362,62304019,52302162 and 52402169)the National Key Research and Development Program of China(2022YFA1203803,2024YFA1212600 and 2023YFF1500401)+5 种基金the Beijing Nova Program(20220484145 and 20230484478)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(2022QNRC001)the Fundamental Research Funds for the Central Universities(FRF-TP-22-004C2,FRF-06500207,FRF-TP-22-004A1,FRF-IDRY-22-016 and FRF-IDRY-23-038)the State Key Lab for Advanced Metals and Materials(2023-Z05)the Postdoctoral Fellowship Program of the China Postdoctoral Science Foudation(GZC20230233)the special support from the Postdoctoral Science Foundation(2023TQ0007).
文摘Two-dimensional(2D)semiconductor-based junction field-effect transistors(JFETs)have emerged as vital architectures for next-generation low-power electronics due to their gate-dielectric-free structure and near-ideal subthreshold swing(SS)potential.Although doping strategies,such as defect engineering and chemical modification,can further enhance the performance of JFETs,complex techniques and uniformly-doping hinder their further applications.Here,we propose a lowpower MoS_(2)/MoTe_(2) JFET utilizing a pre-deposited Au film to dope the gate layer of MoTe_(2),which can uniformly increase the work function of MoTe_(2) and thus elevate heterostructure barrier heights.This method offers strong repeatability,avoids localized states on channel material,and is compatible with integrated circuit manufacturing.The JFETs achieve a near-ideal SS of 62.5 mV dec−1,mobility of 350 cm2 V−1 s−1,high current on/off ratio of 107,low gate leakage of 10−12 A,and low pinch-off voltage of−0.1 V.This strategy provides a universal and simple strategy for low-power circuits.
基金supported by the National Science Foundation of China(Nos.62431018 and 12034001)the National Key R&D Program(Nos.2024YFA1200125 and 2018YFA0307200).
文摘Two-dimensional(2D)materials hold immense potential for next-generation information devices due to their ambipolar transport and tunable electronic states.However,conventional electric-field-driven architectures suffer from inherent carrier-type degeneracy:Electrons and holes generate unidirectional currents,leading to ambiguous state overlaps in multi-level operation.Here,we demonstrate that surface acoustic waves(SAWs)break this symmetry in optically reconfigurable MoTe_(2)/h-BN heterostructures.SAWs induce type-II band modulation in the heterostructure and spatially separate electrons and holes into distinct valleys,enabling bidirectional acoustoelectric currents,whose polarity reverses with carrier type,controlled dynamically via ultraviolet(UV)illumination and gating.Leveraging this mechanism,we realize an 8-state memory device where SAW-driven readout currents changed between positive and negative polarities,achieving enhanced inter-state differentiation compared to voltage-read schemes.For synaptic applications,SAW-driven weight updates in n-and p-type regimes produce anti-symmetric conductance trajectories,eliminating state collisions observed in electric-field-driven counterparts.This work pioneers acoustic wave manipulation of ambipolar transport,offering transformative strategies for degeneracy-free,high-precision neuromorphic electronics.
基金supported by National Key R&D Program of China(No.2023YFA1608701)the National Natural Science Foundation of China(Nos.62274168,11933006,U2141240,and 62005249)+3 种基金Hangzhou Leading Innovation and Entrepreneurship Team(No.TD2020002)Open Fund of State Key Laboratory of Infrared Physics(SITP-NLIST-YB-2023-13)Natural Science Foundation of Zhejiang Province(Nos.LZ24F050006 and LQ20F050005)the Research Funds of Hangzhou Institute for Advanced Study,UCAS(Nos.B02006C019025 and B02006C021010).
文摘The realization of controllable polarity photoresponse within a single device is a crucial advancement for simulating biological bipolar vision cells to drive the development of next-generation optoelectronic technologies.Nevertheless,current polarity photodetectors face significant challenges in fully suppressing symmetric photocurrent cancellation and optimizing carrier transport efficiency.Here,we propose a graphene-intercalated MoS_(2)/MoTe_(2)heterojunction,featuring a tailorable built-in electric field and a high efficiency transport channel.Spatially resolved photocurrent reveals that the controllable polarity photoresponse originates from the bias-dependent equivalent built-in electric field of MoS_(2)/MLG/MoTe_(2)heterojunction.The controllable polarity photoresponse realizes a large-area uniform“heart-shaped”photocurrent region.In enhanced polarity photoresponse mode,the photodetector exhibits broadband detection capabilities from visible(638 nm)to infrared(1550 nm)light,achieving a high responsivity of 18.1 A/W and an excellent detectivity of 2.8×10^(12)Jones,as well as fast response times of 94/119μs.Furthermore,precise imaging with a resolution better than 0.5 mm was successfully demonstrated,highlighting its polarity photoresponse for practical imaging applications.This work provides a new paradigm for controllable polarity photoresponse programmed by intercalated low-dimensional material structures,paving the way for next-generation intelligent sensing chips.
基金support from Research Groups of the National Natural Science Foundation of China(No.52121004)Hunan Key R&D Program Project(No.2022GK2005)+1 种基金the National Key R&D Program of the Ministry of Science and Technology of China(No.2022YFA1203801)the National Natural Science Foundation of China(Nos.51991340 and 51991343).
文摘Phase transition and edge structure reconstruction of twodimensional(2D)materials are critical for modulating their properties and applications.Here,we employ a hydrogen-assisted annealing method to accomplish the extensive transformation from a 2H MoTe_(2)single crystal to Mo_(6)Te_(6)nanowires and quasi-2D Mo_(6)Te_(6)nanoribbons.Introducing hydrogen gas during atmospheric pressure annealing process generates a Te-poor chemical environment,which makes the transformations energetically favorable and is essential for the fast growth of Mo_(6)Te_(6)nanowires.Mo_(6)Te_(6)nanowires nucleate at the exposed edges of 2H MoTe_(2)and grow along its[1120],[2110],and[1210]crystallographic directions,demonstrating long-range order and forming quais-2D nanoribbons with lengths up to 50μm.Finally,nanoribbons align in sixfold oriented directions and form an array within 3 mm^(2)area on SiO_(2)/Si substrate.Mo_(6)Te_(6)nanowires display metallic behavior and have large charge transfer with Rhodamine 6G,making them excellent substrates for surface-enhanced Raman scattering.It shows a low detectable concentration of 10^(-13)mol/L for Rhodamine 6G and a Raman enhancement factor of 7×10^(8).Our findings provide an economic and efficient synthesis method for producing sixfold-oriented Mo_(6)Te_(6)nanowires and nanoribbons networks,which can serve as platform for exploring lowdimensional physical properties,designing electronic devices,and applications in analytical chemistry.
