TiO_(2)is a well-known photocatalyst with a band gap of 3.2 eV,yet its ability to absorb light is limited to the short wavelengths of ultraviolet light.To achieve a more effective photocatalytic material,we have desig...TiO_(2)is a well-known photocatalyst with a band gap of 3.2 eV,yet its ability to absorb light is limited to the short wavelengths of ultraviolet light.To achieve a more effective photocatalytic material,we have designed two-dimensional semiconductor TiOS materials using swarm intelligence algorithms combined with first-principles calculations.Three stable low-energy structures with space groups of P2_(1)/m,P3m1 and P2_(1)/c are identified.Among these structures,the Janus P3m1 phase is a direct bandgap semiconductor,while the P2_(1)/m and P2_(1)/c phases are indirect bandgap semiconductors.Utilizing the accurate hybrid density functional HSE06 method,the band gaps of the three structures are calculated to be 2.34 eV(P2_(1)/m),2.24 eV(P3m1)and 3.22 eV(P2_(1)/c).Optical calculations reveal that TiOS materials exhibit a good light-harvesting capability in both visible and ultraviolet spectral ranges.Moreover,the photocatalytic calculations also indicate that both P2_(1)/m and P3m1 TiOS can provide a strong driving force for converting H_(2)O to H_(2)and O_(2)in an acidic environment with pH=0.The structural stabilities,mechanical properties,electronic structures and hydrogen evolution reaction activities are also discussed in detail.Our research suggests that two-dimensional TiOS materials have potential applications in both semiconductor devices and photocatalysis.展开更多
With the rapid development of information technology,the demand for high-performance and low-power microprocessors continues to grow.Traditional silicon-based semiconductor technologies have encountered numerous bottl...With the rapid development of information technology,the demand for high-performance and low-power microprocessors continues to grow.Traditional silicon-based semiconductor technologies have encountered numerous bottlenecks in performance enhancement,such as drain-induced barrier lowering,reduced mobility caused by interface scattering,and limited current on/off ratios.展开更多
The investigation of two-dimensional(2D)materials has advanced into practical device applications,such as cascaded logic stages.However,incompatible electrical properties and inappropriate logic levels remain enormous...The investigation of two-dimensional(2D)materials has advanced into practical device applications,such as cascaded logic stages.However,incompatible electrical properties and inappropriate logic levels remain enormous challenges.In this work,a doping-free strategy is investigated by top gated(TG)MoS_(2) field-effect transistors(FETs)using various metal gates(Au,Cu,Ag,and Al).These metals with different work functions provide a convenient tuning knob for controlling threshold voltage(V_(th))for MoS_(2) FETs.For instance,the Al electrode can create an extra electron doping(n-doping)behavior in the MoS_(2) TG-FETs due to a dipole effect at the gate-dielectric interface.In this work,by achieving matched electrical properties for the load transistor and the driver transistor in an inverter circuit,we successfully demonstrate wafer-scale MoS_(2) inverter arrays with an optimized inverter switching threshold voltage(V_(M))of 1.5 V and a DC voltage gain of 27 at a supply voltage(V_(DD))of 3 V.This work offers a novel scheme for the fabrication of fully integrated multistage logic circuits based on wafer-scale MoS_(2) film.展开更多
GaTe is a two-dimensionalⅢ-Ⅵsemiconductor with suitable direct bandgap of~1.65 eV and high photoresponsivity,which makes it a promising candidate for optoelectronic applications.GaTe exists in two crystalline phases...GaTe is a two-dimensionalⅢ-Ⅵsemiconductor with suitable direct bandgap of~1.65 eV and high photoresponsivity,which makes it a promising candidate for optoelectronic applications.GaTe exists in two crystalline phases:monoclinic(m-GaTe,with space group C2/m)and hexagonal(h-GaTe,with space group P63/mmc).The phase transition between the two phases was reported under temperature-varying conditions,such as annealing,laser irradiation,etc.The explicit phase transition temperature and energy barrier during the temperature-induced phase transition have not been explored.In this work,we present a comprehensive study of the phase transition process by using first-principles energetic and phonon calculations within the quasi-harmonic approximation framework.We predicted that the phase transition from h-GaTe to m-GaTe occurs at the temperature decreasing to 261 K.This is in qualitative agreement with the experimental observations.It is a two-step transition process with energy barriers 199 meV and 288 meV,respectively.The relatively high energy barriers demonstrate the irreversible nature of the phase transition.The electronic and phonon properties of the two phases were further investigated by comparison with available experimental and theoretical results.Our results provide insightful understanding on the process of temperature-induced phase transition of GaTe.展开更多
Two-dimensional(2D)semiconductors isoelectronic to phosphorene have been drawing much attention recently due to their promising applications for next-generation(opt)electronics.This family of 2D materials contains mor...Two-dimensional(2D)semiconductors isoelectronic to phosphorene have been drawing much attention recently due to their promising applications for next-generation(opt)electronics.This family of 2D materials contains more than 400members,including(a)elemental group-V materials,(b)binary III–VII and IV–VI compounds,(c)ternary III–VI–VII and IV–V–VII compounds,making materials design with targeted functionality unprecedentedly rich and extremely challenging.To shed light on rational functionality design with this family of materials,we systemically explore their fundamental band gaps and alignments using hybrid density functional theory(DFT)in combination with machine learning.First,calculations are performed using both the Perdew–Burke–Ernzerhof exchange–correlation functional within the generalgradient-density approximation(GGA-PBE)and Heyd–Scuseria–Ernzerhof hybrid functional(HSE)as a reference.We find this family of materials share similar crystalline structures,but possess largely distributed band-gap values ranging approximately from 0 eV to 8 eV.Then,we apply machine learning methods,including linear regression(LR),random forest regression(RFR),and support vector machine regression(SVR),to build models for the prediction of electronic properties.Among these models,SVR is found to have the best performance,yielding the root mean square error(RMSE)less than 0.15 eV for the predicted band gaps,valence-band maximums(VBMs),and conduction-band minimums(CBMs)when both PBE results and elemental information are used as features.Thus,we demonstrate that the machine learning models are universally suitable for screening 2D isoelectronic systems with targeted functionality,and especially valuable for the design of alloys and heterogeneous systems.展开更多
Inspired by the recently predicted 2D MX_(2)Y_(6)(M=metal element;X=Si/Ge/Sn;Y=S/Se/Te),we explore the possible applications of alkaline earth metal(using magnesium as example)in this family based on the idea of eleme...Inspired by the recently predicted 2D MX_(2)Y_(6)(M=metal element;X=Si/Ge/Sn;Y=S/Se/Te),we explore the possible applications of alkaline earth metal(using magnesium as example)in this family based on the idea of element replacement and valence electron balance.Herein,we report a new family of 2D quaternary compounds,namely MgMX_(2)Y_(6)(M=Ti/Zr/Hf;X=Si/Ge;Y=S/Se/Te)monolayers,with superior kinetic,thermodynamic and mechanical stability.In addition,our results indicate that MgMX_(2)Y_(6)monolayers are all indirect band gap semiconductors with band gap values ranging from 0.870 to 2.500 eV.Moreover,the band edges and optical properties of 2D MgMX_(2)Y_(6)are suitable for constructing multifunctional optoelectronic devices.Furthermore,for comparison,the mechanical,electronic and optical properties of In_(2)X_(2)Y_(6)monolayers have been discussed in detail.The success of introducing Mg into the 2D MX_(2)Y_(6)family indicates that more potential materials,such as Caand Sr-based 2D MX_(2)Y_(6)monolayers,may be discovered in the future.Therefore,this work not only broadens the existing family of 2D semiconductors,but it also provides beneficial results for the future.展开更多
We report the synthesis and characterization of a Si-based ternary semiconductor Mg_(3)Si_(2)Te_(6),which exhibits a quasitwo-dimensional structure,where the trigonal Mg_(3)Si_(2)Te_(6)layers are separated by Mg ions....We report the synthesis and characterization of a Si-based ternary semiconductor Mg_(3)Si_(2)Te_(6),which exhibits a quasitwo-dimensional structure,where the trigonal Mg_(3)Si_(2)Te_(6)layers are separated by Mg ions.Ultraviolet-visible absorption spectroscopy and density functional theory calculations were performed to investigate the electronic structure.The experimentally determined direct band gap is 1.39 eV,consistent with the value of the density function theory calculations.Our results reveal that Mg_(3)Si_(2)Te_(6)is a direct gap semiconductor,which is a potential candidate for near-infrared optoelectronic devices.展开更多
Two-dimensional (2D) ferromagnetic semiconductors have been recognized as the most promising candidates for next-generation low-cost, high-performance and nano-scale spintronic applications such as spin field-effect t...Two-dimensional (2D) ferromagnetic semiconductors have been recognized as the most promising candidates for next-generation low-cost, high-performance and nano-scale spintronic applications such as spin field-effect transistors and quantum computation/communication. However, as one of the 125 important scientific issues raised by Science journal in 2005 that "is it possible to create magnetic semiconductors that work at room temperature?", how to achieve a feasible ferromagnetic semiconductor with high Curie temperature is still a long-standing challenge despite of tremendous efforts have been devoted in this field since 1960s. The recent discovery of 2D ferromagnetic semiconductors Cr2Ge2Te6 and CrI3 has evoked new research interests in 2D intrinsic ferromagnetic semiconductors. But the low Curie temperature (<45 K) of these materials is still badly hindering their industrial applications.展开更多
Since the discovery of graphene,two-dimensional(2D)semiconductors have been attracted intensive interest due to their unique properties.They have exhibited potential applications in next generation electronic and opto...Since the discovery of graphene,two-dimensional(2D)semiconductors have been attracted intensive interest due to their unique properties.They have exhibited potential applications in next generation electronic and optoelectronic devices.However,most of the 2D semiconductor are known to suffer from the ambient oxidation which degrade the materials and therefore hinder us from the intrinsic materials’properties and the optimized performance of devices.In this review,we summarize the recent progress on both fundamentals and applications of the oxidations of 2D semiconductors.We begin with the oxidation mechanisms in black phosphorus,transition metal dichalcogenides and transition metal monochalcogenides considering the factors such as oxygen,water,and light.Then we show the commonly employed passivation techniques.In the end,the emerging applications utilizing controlled oxidations will be introduced.展开更多
Two-dimensional(2D)layered materials,including graphene,black phosphorus(BP)and transition metal dichalcogenide(TMD)such as molybdenum disulfide(Mo S2),tungsten diselenide(WSe2),have attracted increasing attention for...Two-dimensional(2D)layered materials,including graphene,black phosphorus(BP)and transition metal dichalcogenide(TMD)such as molybdenum disulfide(Mo S2),tungsten diselenide(WSe2),have attracted increasing attention for the application in electronic and optoelectronic devices.Contacts,which are the communication links between these 2D materials and external circuitry,have significant effects on the performance of electronic and optoelectronic devices.However,the performance of devices based on 2D semiconductors(SCs)is often limited by the contacts.Here,we provide a comprehensive overview of the basic physics and role of contacts in 2D SCs,elucidating Schottky barrier nature and Fermi level pinning effect at metal/2D SCs contact interface.The progress of contact engineering,including traditional metals contacts and metallic 2D materials contacts,for improving the performance of 2D SCs based devices is presented.Traditional metal contacts,named 3D top and edge contacts,are discussed briefly.Meanwhile,methods of building 2D materials contacts(2D top contact and 2D edge contact)are discussed in detail,such as chemical vapor deposition(CVD)growth of 2D metallic material contacts,phase engineered metallic phase contacts and intercalation induced metallic state contacts.Finally,the challenges and opportunities of contact engineering for 2D SCs are outlined.展开更多
High-performance electronics and optoelectronics play vital roles in modern society,as they are the fundamental building blocks of functional devices and systems.Two-dimensional semiconductor materials(2D-SCMs)are pot...High-performance electronics and optoelectronics play vital roles in modern society,as they are the fundamental building blocks of functional devices and systems.Two-dimensional semiconductor materials(2D-SCMs)are potential candidates for highperformance electronics and optoelectronics due to their excellent physical,chemical,electrical,and photonic properties.Owing to their special crystalline structure,they also present unique piezoelectricity,which opens a new door to the innovative fields of piezotronics and piezo-phototronics.Piezotronics and piezophototronics utilize the piezoelectric polarization charges produced when the 2D-SCMs undergo externally applied strains/stresses to modulate the performance of 2D-SCMs-based electronics and optoelectronics.In this review,firstly,the growth methods and piezoelectric properties of 2D-SCMs are stated,and the mechanisms of piezotronics and piezo-phototronics are also introduced.Afterwards,the recent progress of piezotronics and piezo-phototronics in high-performance 2D-SMCs-based electronics and optoelectronics are systematically reviewed.In addition,the functional devices and systems based on the piezotronics and piezo-phototronics in 2D-SMCs have been summarized.Finally,the research progresses are summarized,and future perspectives are proposed.展开更多
As emerging two-dimensional(2D)materials,carbides and nitrides(MXenes)could be solid solutions or organized structures made up of multi-atomic layers.With remarkable and adjustable electrical,optical,mechanical,and el...As emerging two-dimensional(2D)materials,carbides and nitrides(MXenes)could be solid solutions or organized structures made up of multi-atomic layers.With remarkable and adjustable electrical,optical,mechanical,and electrochemical characteristics,MXenes have shown great potential in brain-inspired neuromorphic computing electronics,including neuromorphic gas sensors,pressure sensors and photodetectors.This paper provides a forward-looking review of the research progress regarding MXenes in the neuromorphic sensing domain and discussed the critical challenges that need to be resolved.Key bottlenecks such as insufficient long-term stability under environmental exposure,high costs,scalability limitations in large-scale production,and mechanical mismatch in wearable integration hinder their practical deployment.Furthermore,unresolved issues like interfacial compatibility in heterostructures and energy inefficiency in neu-romorphic signal conversion demand urgent attention.The review offers insights into future research directions enhance the fundamental understanding of MXene properties and promote further integration into neuromorphic computing applications through the convergence with various emerging technologies.展开更多
Organic magnetic semiconductors have aroused much attention for spintronic applications. However, it remains challenging to achieve organic semiconductors with strong room-temperature ferromagnetism. Here, we report a...Organic magnetic semiconductors have aroused much attention for spintronic applications. However, it remains challenging to achieve organic semiconductors with strong room-temperature ferromagnetism. Here, we report a two-dimensional (2D) tetragonal organic-inorganic ferrimagnetic (FIM) semiconductor of Fe_(14)Se_(16)(peha)_(0.7) (peha = pentaethylenehexamine) with excellent thermal stability and a Curie temperature (T_(C)) higher than 519 K. Magnetic and Mössbauer measurements reveal a long-range magnetic ordering in single crystalline Fe_(14)Se_(16)(peha)0.7 nanosheets. The saturation magnetization and coercivity are 5.9 emu g^(−1) and 0.42 kOe at 5 K, which slightly reduces to 4.6 emu g^(−1) and ∼0 Oe at 300 K. A direct optical bandgap of 2.22 eV is obtained by tuning electronic structure of β-Fe3Se4 host layers through spacer layers consisting of Fe^(3+) and peha. Electrical and Seebeck coefficient data indicate that the n-type semiconductor follows the thermally-activated conduction mechanism (lnρ ∝ T^(−1)) in a range of 130–300 K with an activation energy (Ea) of 62.69 meV. Thermal conductivity is 2.5 W m^(−1) K^(−1) at 300 K, while the Wiedemann–Franz law is strongly violated according to electrical-thermal transport data due to weak incorporation of organic spacer layers and host layers. This study sets the stage for exploiting new room-temperature organic magnetic semiconductor systems for spintronic materials.展开更多
Crystallization is of fundamental importance in nature and industry[1,2].Single-crystal materials,with their excellent mechanical,optical,and electrical properties,have drawn much attention in semiconductor technologi...Crystallization is of fundamental importance in nature and industry[1,2].Single-crystal materials,with their excellent mechanical,optical,and electrical properties,have drawn much attention in semiconductor technologies regarding singlenucleus crystallization[3].展开更多
1.INTRODUCTION Technology advancements have often been propelled by material innovations.Recently,two-dimensional(2D)materi-als have attracted tremendous interest in construct atomic-level architectures for their uniq...1.INTRODUCTION Technology advancements have often been propelled by material innovations.Recently,two-dimensional(2D)materi-als have attracted tremendous interest in construct atomic-level architectures for their unique quantum confinement,surface effects,ultrathin thickness,and integration with high density.Hence,manipulating 2D materials with atomic-scale precision is crucial for the development of next-generation material design toolbox.展开更多
We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW...We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.展开更多
Two-dimensional(2D)semiconductors,especially transition metal dichalcogenides,are the most competitive channel materials for post-silicon electronics due to their great miniaturization potential and advantages of high...Two-dimensional(2D)semiconductors,especially transition metal dichalcogenides,are the most competitive channel materials for post-silicon electronics due to their great miniaturization potential and advantages of high performance and low power consumption.The atomically thick structural advantage of 2D semiconductors also makes their strain tolerance far greater than that of silicon,making them an ideal platform for implementing and expanding strain technology in post-silicon electronics.The strain technology of 2D semiconductors can not only improve the mobility and on-current of a single device but also be more conveniently applied to the integration of 3D gate-all-around and complementary field-effect transistors.In recent years,a series of strain technologies with different characteristics have been developed for 2D semiconductors and transistor devices,including lattice mismatch,thermal expansion coefficient mismatch,substrate-induced stress technology,and process-induced stress.At present,it is necessary to sort out the existing technical foundation and propose strain strategies for 2D semiconductors that better suit industrialization and future 3D integration to meet the needs of high-performance post-silicon electronics.This review takes the mature strained silicon technology as a benchmark,systematically reviews the current strain technology of 2D semiconductors and devices,deeply analyzes the limitations of existing technologies,and proposes the development direction of strain technology for 2D semiconductors suitable for industrial applications and future 3D integration.展开更多
Metal-oxide-semiconductor field effect transistors(MOSFET)based on two-dimensional(2D)semiconductors have attracted extensive attention owing to their excellent transport properties,atomically thin geometry,and tunabl...Metal-oxide-semiconductor field effect transistors(MOSFET)based on two-dimensional(2D)semiconductors have attracted extensive attention owing to their excellent transport properties,atomically thin geometry,and tunable bandgaps.Besides improving the transistor performance of individual device,lots of efforts have been devoted to achieving 2D logic functions or integrated circuit towards practical application.In this review,we discussed the recent progresses of 2D-based logic circuit.We will first start with the different methods for realization of n-type metal-oxide-semiconductor(NMOS)-only(or p-type metal-oxide-semiconductor(PMOS)-only)logic circuit.Next,various device polarity control and complementary-metal-oxide-semiconductor(CMOS)approaches are summarized,including utilizing different 2D semiconductors with intrinsic complementary doping,charge transfer doping,contact engineering,and electrostatics doping.We will discuss the merits and drawbacks of each approach,and lastly conclude with a short perspective on the challenges and future developments of 2D logic circuit.展开更多
The electronic structures and magnetic properties of strained monolayer MnPSe3 are investigated sys- tematically via first-principles calculations. It is found that the magnetic ground state of monolayer MnPSe3 can be...The electronic structures and magnetic properties of strained monolayer MnPSe3 are investigated sys- tematically via first-principles calculations. It is found that the magnetic ground state of monolayer MnPSe3 can be significantly affected by biaxial strain engineering, while the semiconducting char- acteristics are well-preserved. Owing to the sensitivity of the magnetic coupling towards structural deformation, a biaxial tensile strain of approximately 13% can lead to an antiferromagnetic （AFM）- ferromagnetic （FM） transition. The strain-dependent magnetic stability is mainly attributed to the competition of the direct AFM interaction and indirect FM superexchange interaction between the two nearest-neighbor Mn atoms. In addition, we find that FM MnPSe3 is an intrinsic half semiconductor with large spin exchange splitting in the conduction bands, which is crucial for the spin-polarized carrier injection and detection. The sensitive interdependence among the external stimuli, electronic structure, and magnetic coupling makes monolayer MnPSe3 a promising candidate for spintronics.展开更多
Metal–semiconductor contacts are crucial components in semiconductor devices.Ultrathin two-dimensional transition-metal dichalcogenide semiconductors can sustain transistor scaling for next-generation integrated circ...Metal–semiconductor contacts are crucial components in semiconductor devices.Ultrathin two-dimensional transition-metal dichalcogenide semiconductors can sustain transistor scaling for next-generation integrated circuits.However,their performance is often degraded by conventional metal deposition,which results in a high barrier due to chemical disorder and Fermi-level pinning(FLP).Although,transferring electrodes can address these issues,they are limited in achieving universal transfer of full-class metals due to strong adhesion between pre-deposited metals and substrates.Here,we propose a nanobelt-assisted transfer strategy that can avoid the adhesion limitation and enables the universal transfer of over 20 different types of electrodes.Our contacts obey the Schottky–Mott rule and exhibit a FLP of S=0.99.Both the electron and hole contacts show record-low Schottky barriers of 4.2 and 11.2 meV,respectively.As a demonstration,we construct a doping-free WSe_(2) inverter with these high-performance contacts,which exhibits a static power consumption of only 58 pW.This strategy provides a universal method of electrode preparation for building high-performance post-Moore electronic devices.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52272219 and U1904612)the Natural Science Foundation of Henan Province(Grant No.242300421191).
文摘TiO_(2)is a well-known photocatalyst with a band gap of 3.2 eV,yet its ability to absorb light is limited to the short wavelengths of ultraviolet light.To achieve a more effective photocatalytic material,we have designed two-dimensional semiconductor TiOS materials using swarm intelligence algorithms combined with first-principles calculations.Three stable low-energy structures with space groups of P2_(1)/m,P3m1 and P2_(1)/c are identified.Among these structures,the Janus P3m1 phase is a direct bandgap semiconductor,while the P2_(1)/m and P2_(1)/c phases are indirect bandgap semiconductors.Utilizing the accurate hybrid density functional HSE06 method,the band gaps of the three structures are calculated to be 2.34 eV(P2_(1)/m),2.24 eV(P3m1)and 3.22 eV(P2_(1)/c).Optical calculations reveal that TiOS materials exhibit a good light-harvesting capability in both visible and ultraviolet spectral ranges.Moreover,the photocatalytic calculations also indicate that both P2_(1)/m and P3m1 TiOS can provide a strong driving force for converting H_(2)O to H_(2)and O_(2)in an acidic environment with pH=0.The structural stabilities,mechanical properties,electronic structures and hydrogen evolution reaction activities are also discussed in detail.Our research suggests that two-dimensional TiOS materials have potential applications in both semiconductor devices and photocatalysis.
文摘With the rapid development of information technology,the demand for high-performance and low-power microprocessors continues to grow.Traditional silicon-based semiconductor technologies have encountered numerous bottlenecks in performance enhancement,such as drain-induced barrier lowering,reduced mobility caused by interface scattering,and limited current on/off ratios.
基金supported by the National Key Research and Development Program (No.2016YFA0203900)Innovation Program of Shanghai Municipal Education Commission (No.2021–01–07–00–07-E00077)+1 种基金Shanghai Municipal Science and Technology Commission (No.21DZ1100900)National Natural Science Foundation of China (Nos.51802041,61904032,and 61874154)。
文摘The investigation of two-dimensional(2D)materials has advanced into practical device applications,such as cascaded logic stages.However,incompatible electrical properties and inappropriate logic levels remain enormous challenges.In this work,a doping-free strategy is investigated by top gated(TG)MoS_(2) field-effect transistors(FETs)using various metal gates(Au,Cu,Ag,and Al).These metals with different work functions provide a convenient tuning knob for controlling threshold voltage(V_(th))for MoS_(2) FETs.For instance,the Al electrode can create an extra electron doping(n-doping)behavior in the MoS_(2) TG-FETs due to a dipole effect at the gate-dielectric interface.In this work,by achieving matched electrical properties for the load transistor and the driver transistor in an inverter circuit,we successfully demonstrate wafer-scale MoS_(2) inverter arrays with an optimized inverter switching threshold voltage(V_(M))of 1.5 V and a DC voltage gain of 27 at a supply voltage(V_(DD))of 3 V.This work offers a novel scheme for the fabrication of fully integrated multistage logic circuits based on wafer-scale MoS_(2) film.
基金Project supported by the National Natural Science Foundation of China(Grant No.62004080)Postdoctoral Innovative Talents Supporting Program(Grant No.BX20190143)+1 种基金China Postdoctoral Science Foundation(2020M670834)Jilin Province Science and Technology Development Program,China(Grant No.20190201016JC)。
文摘GaTe is a two-dimensionalⅢ-Ⅵsemiconductor with suitable direct bandgap of~1.65 eV and high photoresponsivity,which makes it a promising candidate for optoelectronic applications.GaTe exists in two crystalline phases:monoclinic(m-GaTe,with space group C2/m)and hexagonal(h-GaTe,with space group P63/mmc).The phase transition between the two phases was reported under temperature-varying conditions,such as annealing,laser irradiation,etc.The explicit phase transition temperature and energy barrier during the temperature-induced phase transition have not been explored.In this work,we present a comprehensive study of the phase transition process by using first-principles energetic and phonon calculations within the quasi-harmonic approximation framework.We predicted that the phase transition from h-GaTe to m-GaTe occurs at the temperature decreasing to 261 K.This is in qualitative agreement with the experimental observations.It is a two-step transition process with energy barriers 199 meV and 288 meV,respectively.The relatively high energy barriers demonstrate the irreversible nature of the phase transition.The electronic and phonon properties of the two phases were further investigated by comparison with available experimental and theoretical results.Our results provide insightful understanding on the process of temperature-induced phase transition of GaTe.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFA0206301)。
文摘Two-dimensional(2D)semiconductors isoelectronic to phosphorene have been drawing much attention recently due to their promising applications for next-generation(opt)electronics.This family of 2D materials contains more than 400members,including(a)elemental group-V materials,(b)binary III–VII and IV–VI compounds,(c)ternary III–VI–VII and IV–V–VII compounds,making materials design with targeted functionality unprecedentedly rich and extremely challenging.To shed light on rational functionality design with this family of materials,we systemically explore their fundamental band gaps and alignments using hybrid density functional theory(DFT)in combination with machine learning.First,calculations are performed using both the Perdew–Burke–Ernzerhof exchange–correlation functional within the generalgradient-density approximation(GGA-PBE)and Heyd–Scuseria–Ernzerhof hybrid functional(HSE)as a reference.We find this family of materials share similar crystalline structures,but possess largely distributed band-gap values ranging approximately from 0 eV to 8 eV.Then,we apply machine learning methods,including linear regression(LR),random forest regression(RFR),and support vector machine regression(SVR),to build models for the prediction of electronic properties.Among these models,SVR is found to have the best performance,yielding the root mean square error(RMSE)less than 0.15 eV for the predicted band gaps,valence-band maximums(VBMs),and conduction-band minimums(CBMs)when both PBE results and elemental information are used as features.Thus,we demonstrate that the machine learning models are universally suitable for screening 2D isoelectronic systems with targeted functionality,and especially valuable for the design of alloys and heterogeneous systems.
基金supported by the National Natural Science Foundation of China (Grant No. 61974049, 62222404 61974050)National Key Research and Development Plan of China (Grant No. 2021YFB3601200)
文摘Inspired by the recently predicted 2D MX_(2)Y_(6)(M=metal element;X=Si/Ge/Sn;Y=S/Se/Te),we explore the possible applications of alkaline earth metal(using magnesium as example)in this family based on the idea of element replacement and valence electron balance.Herein,we report a new family of 2D quaternary compounds,namely MgMX_(2)Y_(6)(M=Ti/Zr/Hf;X=Si/Ge;Y=S/Se/Te)monolayers,with superior kinetic,thermodynamic and mechanical stability.In addition,our results indicate that MgMX_(2)Y_(6)monolayers are all indirect band gap semiconductors with band gap values ranging from 0.870 to 2.500 eV.Moreover,the band edges and optical properties of 2D MgMX_(2)Y_(6)are suitable for constructing multifunctional optoelectronic devices.Furthermore,for comparison,the mechanical,electronic and optical properties of In_(2)X_(2)Y_(6)monolayers have been discussed in detail.The success of introducing Mg into the 2D MX_(2)Y_(6)family indicates that more potential materials,such as Caand Sr-based 2D MX_(2)Y_(6)monolayers,may be discovered in the future.Therefore,this work not only broadens the existing family of 2D semiconductors,but it also provides beneficial results for the future.
基金the National Natural Science Foundation of China(Grant Nos.12174454,11904414,11904416,and 12104427)the Guangdong Basic and Applied Basic Research Foundation,China(Grant No.2021B1515120015)+1 种基金the Guangzhou Basic and Applied Basic Research Foundation(Grant No.202201011123)the National Key Research and Development Program of China(Grant No.2019YFA0705702).
文摘We report the synthesis and characterization of a Si-based ternary semiconductor Mg_(3)Si_(2)Te_(6),which exhibits a quasitwo-dimensional structure,where the trigonal Mg_(3)Si_(2)Te_(6)layers are separated by Mg ions.Ultraviolet-visible absorption spectroscopy and density functional theory calculations were performed to investigate the electronic structure.The experimentally determined direct band gap is 1.39 eV,consistent with the value of the density function theory calculations.Our results reveal that Mg_(3)Si_(2)Te_(6)is a direct gap semiconductor,which is a potential candidate for near-infrared optoelectronic devices.
文摘Two-dimensional (2D) ferromagnetic semiconductors have been recognized as the most promising candidates for next-generation low-cost, high-performance and nano-scale spintronic applications such as spin field-effect transistors and quantum computation/communication. However, as one of the 125 important scientific issues raised by Science journal in 2005 that "is it possible to create magnetic semiconductors that work at room temperature?", how to achieve a feasible ferromagnetic semiconductor with high Curie temperature is still a long-standing challenge despite of tremendous efforts have been devoted in this field since 1960s. The recent discovery of 2D ferromagnetic semiconductors Cr2Ge2Te6 and CrI3 has evoked new research interests in 2D intrinsic ferromagnetic semiconductors. But the low Curie temperature (<45 K) of these materials is still badly hindering their industrial applications.
基金partially supported by the National Natural Science Foundation of China(No.11804397)the Hunan High-Level Talent Program(No.2019RS1006)。
文摘Since the discovery of graphene,two-dimensional(2D)semiconductors have been attracted intensive interest due to their unique properties.They have exhibited potential applications in next generation electronic and optoelectronic devices.However,most of the 2D semiconductor are known to suffer from the ambient oxidation which degrade the materials and therefore hinder us from the intrinsic materials’properties and the optimized performance of devices.In this review,we summarize the recent progress on both fundamentals and applications of the oxidations of 2D semiconductors.We begin with the oxidation mechanisms in black phosphorus,transition metal dichalcogenides and transition metal monochalcogenides considering the factors such as oxygen,water,and light.Then we show the commonly employed passivation techniques.In the end,the emerging applications utilizing controlled oxidations will be introduced.
基金supported by the National Key R&D Program of China(Grant No.2018YFA0306900)the Natural Science Foundation of China(Grant No.51872012)。
文摘Two-dimensional(2D)layered materials,including graphene,black phosphorus(BP)and transition metal dichalcogenide(TMD)such as molybdenum disulfide(Mo S2),tungsten diselenide(WSe2),have attracted increasing attention for the application in electronic and optoelectronic devices.Contacts,which are the communication links between these 2D materials and external circuitry,have significant effects on the performance of electronic and optoelectronic devices.However,the performance of devices based on 2D semiconductors(SCs)is often limited by the contacts.Here,we provide a comprehensive overview of the basic physics and role of contacts in 2D SCs,elucidating Schottky barrier nature and Fermi level pinning effect at metal/2D SCs contact interface.The progress of contact engineering,including traditional metals contacts and metallic 2D materials contacts,for improving the performance of 2D SCs based devices is presented.Traditional metal contacts,named 3D top and edge contacts,are discussed briefly.Meanwhile,methods of building 2D materials contacts(2D top contact and 2D edge contact)are discussed in detail,such as chemical vapor deposition(CVD)growth of 2D metallic material contacts,phase engineered metallic phase contacts and intercalation induced metallic state contacts.Finally,the challenges and opportunities of contact engineering for 2D SCs are outlined.
基金supported by the National Natural Science Foundation of China(Grant No.62174131 and 61704135)the China Postdoctoral Science Foundation(Grant No.2018T111055 and 2017M613138)the Postdoctoral Research Project of Shaanxi Province(Grant No.2017BSHEDZZ30).
文摘High-performance electronics and optoelectronics play vital roles in modern society,as they are the fundamental building blocks of functional devices and systems.Two-dimensional semiconductor materials(2D-SCMs)are potential candidates for highperformance electronics and optoelectronics due to their excellent physical,chemical,electrical,and photonic properties.Owing to their special crystalline structure,they also present unique piezoelectricity,which opens a new door to the innovative fields of piezotronics and piezo-phototronics.Piezotronics and piezophototronics utilize the piezoelectric polarization charges produced when the 2D-SCMs undergo externally applied strains/stresses to modulate the performance of 2D-SCMs-based electronics and optoelectronics.In this review,firstly,the growth methods and piezoelectric properties of 2D-SCMs are stated,and the mechanisms of piezotronics and piezo-phototronics are also introduced.Afterwards,the recent progress of piezotronics and piezo-phototronics in high-performance 2D-SMCs-based electronics and optoelectronics are systematically reviewed.In addition,the functional devices and systems based on the piezotronics and piezo-phototronics in 2D-SMCs have been summarized.Finally,the research progresses are summarized,and future perspectives are proposed.
基金supported by the NSFC(12474071)Natural Science Foundation of Shandong Province(ZR2024YQ051,ZR2025QB50)+6 种基金Guangdong Basic and Applied Basic Research Foundation(2025A1515011191)the Shanghai Sailing Program(23YF1402200,23YF1402400)funded by Basic Research Program of Jiangsu(BK20240424)Open Research Fund of State Key Laboratory of Crystal Materials(KF2406)Taishan Scholar Foundation of Shandong Province(tsqn202408006,tsqn202507058)Young Talent of Lifting engineering for Science and Technology in Shandong,China(SDAST2024QTB002)the Qilu Young Scholar Program of Shandong University。
文摘As emerging two-dimensional(2D)materials,carbides and nitrides(MXenes)could be solid solutions or organized structures made up of multi-atomic layers.With remarkable and adjustable electrical,optical,mechanical,and electrochemical characteristics,MXenes have shown great potential in brain-inspired neuromorphic computing electronics,including neuromorphic gas sensors,pressure sensors and photodetectors.This paper provides a forward-looking review of the research progress regarding MXenes in the neuromorphic sensing domain and discussed the critical challenges that need to be resolved.Key bottlenecks such as insufficient long-term stability under environmental exposure,high costs,scalability limitations in large-scale production,and mechanical mismatch in wearable integration hinder their practical deployment.Furthermore,unresolved issues like interfacial compatibility in heterostructures and energy inefficiency in neu-romorphic signal conversion demand urgent attention.The review offers insights into future research directions enhance the fundamental understanding of MXene properties and promote further integration into neuromorphic computing applications through the convergence with various emerging technologies.
基金supported by the National Natural Science Foundation of China(Nos.52371203,51971221 and 52031014).
文摘Organic magnetic semiconductors have aroused much attention for spintronic applications. However, it remains challenging to achieve organic semiconductors with strong room-temperature ferromagnetism. Here, we report a two-dimensional (2D) tetragonal organic-inorganic ferrimagnetic (FIM) semiconductor of Fe_(14)Se_(16)(peha)_(0.7) (peha = pentaethylenehexamine) with excellent thermal stability and a Curie temperature (T_(C)) higher than 519 K. Magnetic and Mössbauer measurements reveal a long-range magnetic ordering in single crystalline Fe_(14)Se_(16)(peha)0.7 nanosheets. The saturation magnetization and coercivity are 5.9 emu g^(−1) and 0.42 kOe at 5 K, which slightly reduces to 4.6 emu g^(−1) and ∼0 Oe at 300 K. A direct optical bandgap of 2.22 eV is obtained by tuning electronic structure of β-Fe3Se4 host layers through spacer layers consisting of Fe^(3+) and peha. Electrical and Seebeck coefficient data indicate that the n-type semiconductor follows the thermally-activated conduction mechanism (lnρ ∝ T^(−1)) in a range of 130–300 K with an activation energy (Ea) of 62.69 meV. Thermal conductivity is 2.5 W m^(−1) K^(−1) at 300 K, while the Wiedemann–Franz law is strongly violated according to electrical-thermal transport data due to weak incorporation of organic spacer layers and host layers. This study sets the stage for exploiting new room-temperature organic magnetic semiconductor systems for spintronic materials.
文摘Crystallization is of fundamental importance in nature and industry[1,2].Single-crystal materials,with their excellent mechanical,optical,and electrical properties,have drawn much attention in semiconductor technologies regarding singlenucleus crystallization[3].
基金the financial support from National Key R&D Program of China(2022YFA1204301)National Natural Science Foundation of China(Grant No.22475186)and Zhejiang University.
文摘1.INTRODUCTION Technology advancements have often been propelled by material innovations.Recently,two-dimensional(2D)materi-als have attracted tremendous interest in construct atomic-level architectures for their unique quantum confinement,surface effects,ultrathin thickness,and integration with high density.Hence,manipulating 2D materials with atomic-scale precision is crucial for the development of next-generation material design toolbox.
基金supported by the National Natural Science Foundation of China(Grant No.12105210)the Knowledge Innovation Program of Wuhan-Basi Research(Grant No.2023010201010149)。
文摘We present a theoretical scheme to realize two-dimensional(2D)asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells(SQWs)structure with resonant tunneling.The SQW structure interacts with a weak probe laser field,a spatially independent 2D standing-wave(SW)field,and a Laguerre–Gaussian(LG)vortex field,respectively.The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation.Because of the existence of vortex light,it is possible to realize asymmetric high-order diffraction in the SQW structure,and then a 2D asymmetric grating is established.By adjusting the detunings of the probe field,vortex field,and SW field,as well as the interaction length,diffraction intensity,and direction of the 2D asymmetric electromagnetically induced grating(EIG)can be controlled effectively.In addition,the number of orbital angular momenta(OAM)and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions.High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme.Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.
基金the National Natural Science Foundation of China(92163205,52225206,52188101,52303362,62322402,52350301,92463308,52250398,62204012,62304019,52302162,and 52402169)the National Key Research and Development Program of China(2022YFA1203803,2024YFA1212600,and 2023YFF1500401)+6 种基金the special support from the Postdoctoral Science Foundation(2023TQ0007)the Postdoctoral Science Foundation(2023M740031)the Beijing Nova Program(20220484145 and 20230484478)the Young Elite Scientists Sponsorship Program by CAST(2022QNRC001)the Fundamental Research Funds for the Central Universities(FRF-TP-22-004C2,FRF-06500207,and FRF-IDRY-23-038)the State Key Lab for Advanced Metals and Materials(2023-Z05)the Postdoctoral Fellowship Program of CPSF(GZC20230233)。
文摘Two-dimensional(2D)semiconductors,especially transition metal dichalcogenides,are the most competitive channel materials for post-silicon electronics due to their great miniaturization potential and advantages of high performance and low power consumption.The atomically thick structural advantage of 2D semiconductors also makes their strain tolerance far greater than that of silicon,making them an ideal platform for implementing and expanding strain technology in post-silicon electronics.The strain technology of 2D semiconductors can not only improve the mobility and on-current of a single device but also be more conveniently applied to the integration of 3D gate-all-around and complementary field-effect transistors.In recent years,a series of strain technologies with different characteristics have been developed for 2D semiconductors and transistor devices,including lattice mismatch,thermal expansion coefficient mismatch,substrate-induced stress technology,and process-induced stress.At present,it is necessary to sort out the existing technical foundation and propose strain strategies for 2D semiconductors that better suit industrialization and future 3D integration to meet the needs of high-performance post-silicon electronics.This review takes the mature strained silicon technology as a benchmark,systematically reviews the current strain technology of 2D semiconductors and devices,deeply analyzes the limitations of existing technologies,and proposes the development direction of strain technology for 2D semiconductors suitable for industrial applications and future 3D integration.
基金the National Natural Science Foundation of China(Nos.51991340,51991341,51802090,and 61874041)from the Hunan Science Fund for Excellent Young Scholars(No.812019037).
文摘Metal-oxide-semiconductor field effect transistors(MOSFET)based on two-dimensional(2D)semiconductors have attracted extensive attention owing to their excellent transport properties,atomically thin geometry,and tunable bandgaps.Besides improving the transistor performance of individual device,lots of efforts have been devoted to achieving 2D logic functions or integrated circuit towards practical application.In this review,we discussed the recent progresses of 2D-based logic circuit.We will first start with the different methods for realization of n-type metal-oxide-semiconductor(NMOS)-only(or p-type metal-oxide-semiconductor(PMOS)-only)logic circuit.Next,various device polarity control and complementary-metal-oxide-semiconductor(CMOS)approaches are summarized,including utilizing different 2D semiconductors with intrinsic complementary doping,charge transfer doping,contact engineering,and electrostatics doping.We will discuss the merits and drawbacks of each approach,and lastly conclude with a short perspective on the challenges and future developments of 2D logic circuit.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 51671142, U1632152, and 51661145026） and the Key Project of Natural Sci- ence Foundation of Tianjin City （Grant No. 16JCZDJC37300）.
文摘The electronic structures and magnetic properties of strained monolayer MnPSe3 are investigated sys- tematically via first-principles calculations. It is found that the magnetic ground state of monolayer MnPSe3 can be significantly affected by biaxial strain engineering, while the semiconducting char- acteristics are well-preserved. Owing to the sensitivity of the magnetic coupling towards structural deformation, a biaxial tensile strain of approximately 13% can lead to an antiferromagnetic （AFM）- ferromagnetic （FM） transition. The strain-dependent magnetic stability is mainly attributed to the competition of the direct AFM interaction and indirect FM superexchange interaction between the two nearest-neighbor Mn atoms. In addition, we find that FM MnPSe3 is an intrinsic half semiconductor with large spin exchange splitting in the conduction bands, which is crucial for the spin-polarized carrier injection and detection. The sensitive interdependence among the external stimuli, electronic structure, and magnetic coupling makes monolayer MnPSe3 a promising candidate for spintronics.
基金National Natural Science Foundation ofChina,Grant/Award Numbers:51991340,51991342,52225206,92163205,52188101,62322402,62204012,52250398,51972022,52303362,62304019the National KeyResearch and Development Program of China,Grant/Award Numbers:2022YFA1203800,2022YFA1203803,2018YFA0703503,2023YFF1500400,2023YFF1500401+7 种基金the Overseas ExpertiseIntroduction Projects for DisciplineInnovation,Grant/Award Number:B14003the Frontier Cross ResearchProject of the Department of Chinese Academy of Sciences,Grant/AwardNumber:XK2023JSA001the Beijing NovaProgram,Grant/Award Numbers:20220484145,20230484478the YoungElite Scientists sponsorship program,Grant/Award Number:2022QNRC001the Fundamental Research Funds for the Central Universities,Grant/Award Number:FRF-06500207the Interdisciplinary Research Project forYoung Teachers of USTB,Grant/Award Numbers:FRF-TP-22-004C2,FRF-IDRY-21-008,FRF-TP-22-004A1,FRF-IDRY-22-016the State Key Lab for Advanced Metals and Materials,Grant/Award Number:2023-Z05the Special supportfrom the Postdoctoral Science Foundation,Grant/Award Number:8206400173。
文摘Metal–semiconductor contacts are crucial components in semiconductor devices.Ultrathin two-dimensional transition-metal dichalcogenide semiconductors can sustain transistor scaling for next-generation integrated circuits.However,their performance is often degraded by conventional metal deposition,which results in a high barrier due to chemical disorder and Fermi-level pinning(FLP).Although,transferring electrodes can address these issues,they are limited in achieving universal transfer of full-class metals due to strong adhesion between pre-deposited metals and substrates.Here,we propose a nanobelt-assisted transfer strategy that can avoid the adhesion limitation and enables the universal transfer of over 20 different types of electrodes.Our contacts obey the Schottky–Mott rule and exhibit a FLP of S=0.99.Both the electron and hole contacts show record-low Schottky barriers of 4.2 and 11.2 meV,respectively.As a demonstration,we construct a doping-free WSe_(2) inverter with these high-performance contacts,which exhibits a static power consumption of only 58 pW.This strategy provides a universal method of electrode preparation for building high-performance post-Moore electronic devices.
