Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)photodetector.Here,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene base...Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)photodetector.Here,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene based flexible NIR photodetector array via a facile photolithography technology.The single ZnSb/Ti_(3)C_(2)T_(x)photodetector exhibited a high light-to-dark current ratio of 4.98,fast response/recovery time(2.5/1.3 s)and excellent stability due to the tight connection between 2D ZnSb nanoplates and 2D Ti_(3)C_(2)T_(x)MXene nanoflakes,and the formed 2D van der Waals heterojunction.Thin polyethylene terephthalate(PET)substrate enables the ZnSb/Ti_(3)C_(2)T_(x)photodetector withstand bending such that stable photoelectrical properties with non-obvious change were maintained over 5000 bending cycles.Moreover,the ZnSb/Ti_(3)C_(2)T_(x)photodetectors were integrated into a 26×5 device array,realizing a NIR image sensing application.展开更多
Twisted van der Waals heterostructures are becoming the building blocks for engineering new device structures, in which their electronic, optical and mechanical properties can be tuned by changing the “twist” angle ...Twisted van der Waals heterostructures are becoming the building blocks for engineering new device structures, in which their electronic, optical and mechanical properties can be tuned by changing the “twist” angle between layers of 2D materials. Such twisted 2D heterostructures offer a unique opportunity to create a new field of “twistronics” by mechanically stacking different 2D van der Waals materials together.展开更多
There is currently great optimism within the electronics community that gallium oxide(Ga_(2)O_(3)) ultra-wide bandgap semiconductors have unprecedented prospects for eventually revolutionizing a rich variety of power ...There is currently great optimism within the electronics community that gallium oxide(Ga_(2)O_(3)) ultra-wide bandgap semiconductors have unprecedented prospects for eventually revolutionizing a rich variety of power electronic applications. Specially, benefiting from its ultra-high bandgap of around 4.8 eV, it is expected that the emerging Ga_(2)O_(3) technology would offer an exciting platform to deliver massively enhanced device performance for power electronics and even completely new applications.展开更多
Gallium oxide(Ga_(2)O_(3))has garnered world-wide atten-tion as an ultrawide-bandgap semiconductor material from the area of power electronics and DUV optical devices benefit-ing from its outstanding electronic and op...Gallium oxide(Ga_(2)O_(3))has garnered world-wide atten-tion as an ultrawide-bandgap semiconductor material from the area of power electronics and DUV optical devices benefit-ing from its outstanding electronic and optoelectronic proper-ties.For one thing,since Ga_(2)O_(3)features high critical break-down field of 8 MV/cm and Baliga’s figure of merit(BFOM)of 3444,it is a promising candidate for advanced high-power applications.For another thing,due to the bandgap directly corresponding to the deep-ultraviolet(DUV)region,Ga_(2)O_(3)is widely used in DUV optoelectronic devices.展开更多
Research on two-dimensional(2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since ...Research on two-dimensional(2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since the mechanical exfoliation of graphene in 2004. Starting from graphene, 2D materials now have become a big family with numerous members and diverse categories. The unique structural features and physicochemical properties of 2D materials make them one class of the most appealing candidates for a wide range of potential applications. In particular, we have seen some major breakthroughs made in the field of 2D materials in last five years not only in developing novel synthetic methods and exploring new structures/properties but also in identifying innovative applications and pushing forward commercialisation. In this review, we provide a critical summary on the recent progress made in the field of 2D materials with a particular focus on last five years. After a brief backgroundintroduction, we first discuss the major synthetic methods for 2D materials, including the mechanical exfoliation, liquid exfoliation, vapor phase deposition, and wet-chemical synthesis as well as phase engineering of 2D materials belonging to the field of phase engineering of nanomaterials(PEN). We then introduce the superconducting/optical/magnetic properties and chirality of 2D materials along with newly emerging magic angle 2D superlattices. Following that, the promising applications of 2D materials in electronics, optoelectronics, catalysis, energy storage, solar cells, biomedicine, sensors, environments, etc. are described sequentially. Thereafter, we present the theoretic calculations and simulations of 2D materials. Finally, after concluding the current progress, we provide some personal discussions on the existing challenges and future outlooks in this rapidly developing field.展开更多
Two-dimensional(2D) anisotropic materials, such as B-P, B-As, GeSe, GeAs, ReSe2, KP15 and their hybrid systems, exhibit unique crystal structures and extraordinary anisotropy. This review presents a comprehensive comp...Two-dimensional(2D) anisotropic materials, such as B-P, B-As, GeSe, GeAs, ReSe2, KP15 and their hybrid systems, exhibit unique crystal structures and extraordinary anisotropy. This review presents a comprehensive comparison of various 2D anisotropic crystals as well as relevant FETs and photodetectors, especially on their particular anisotropy in optical and electrical properties. First, the structure of typical 2D anisotropic crystal as well as the analysis of structural anisotropy is provided. Then, recent researches on anisotropic Raman spectra are reviewed. Particularly, a brief measurement principle of Raman spectra under three typical polarized measurement configurations is introduced. Finally, recent progress on the electrical and photoelectrical properties of FETs and polarization-sensitive photodetectors based on 2D anisotropic materials is summarized for the comparison between different 2D anisotropic materials. Beyond the high response speed, sensitivity and on/off ratio, these 2D anisotropic crystals exhibit highly conduction ratio and dichroic ratio which can be applied in terms of polarization sensors, polarization spectroscopy imaging, optical radar and remote sensing.展开更多
Two-dimensional(2D) magnetic crystals have attracted great attention due to their emerging new physical phenomena. They provide ideal platforms to study the fundamental physics of magnetism in low dimensions. In this ...Two-dimensional(2D) magnetic crystals have attracted great attention due to their emerging new physical phenomena. They provide ideal platforms to study the fundamental physics of magnetism in low dimensions. In this research,magnetic tunneling junctions(MTJs) based on XSe2(X = Mn, V) with room-temperature ferromagnetism were studied using first-principles calculations. A large tunneling magnetoresistance(TMR) of 725.07% was obtained in the MTJs based on monolayer MnSe2. Several schemes were proposed to improve the TMR of these devices. Moreover, the results of our non-equilibrium transport calculations showed that the large TMR was maintained in these devices under a finite bias.The transmission spectrum was analyzed according to the orbital components and the electronic structure of the monolayer XSe2(X = Mn, V). The results in this paper demonstrated that the MTJs based on a 2D ferromagnet with room-temperature ferromagnetism exhibited reliable performance. Therefore, such devices show the possibility for potential applications in spintronics.展开更多
In recent years,low-dimensional materials especially 2D materials have attracted wide attention due to their novel proprieties.Plenty of devices with excellent performance have been made for different applications bas...In recent years,low-dimensional materials especially 2D materials have attracted wide attention due to their novel proprieties.Plenty of devices with excellent performance have been made for different applications basing on 2D materials.In order to further explore the advantages of 2D materials and integrating them into semiconductor fabrication lines,the 2D material/Si heterostructure-based photodetectors played important roles in many different domains due to their price advantage,mature manufacturing craft and good compatibility to integrated circuits.展开更多
With the rapid development of mobile Internet and intelligent devices,flexible electronic technology has attracted wide attention driven by the huge demand of the market.As one type of flexible electronic devices,flex...With the rapid development of mobile Internet and intelligent devices,flexible electronic technology has attracted wide attention driven by the huge demand of the market.As one type of flexible electronic devices,flexible sensors have attracted great interest because of their promising prospects in artificial intelligence,medical health,and environmental protection.In recent years,flexible sensors with high sensitivity,selectivity,good deformability,reliable stability,and portability are urgently needed to meet the developments of artificial skin,human-computer interaction,point of care diagnostics and wearable electronic devices.展开更多
Since the successful fabrication of two-dimensional (2D) ferromagnetic (FM) monolayer CrI3 and Cr2Ge2Te6, 2D FM materials are becoming an exciting research topic in condensed matter physics and materials fields, as th...Since the successful fabrication of two-dimensional (2D) ferromagnetic (FM) monolayer CrI3 and Cr2Ge2Te6, 2D FM materials are becoming an exciting research topic in condensed matter physics and materials fields, as they provide a good platform to explore the fundamental physical properties of magnetic materials under 2D limit. In this review, we summarize the theoretical research progress of intrinsic 2D FM materials and related van der Waals heterostructures (vdWHs) including their electronic structures, magnetism, Curie temperature, valley polarization, and band alignment. Moreover, we also summarize recent researches on the methods that used to regulate the above properties of 2D FM materials and vdWHs, such as defects, doping, strain, electric field and interlayer coupling. These studies show that 2D FM materials have broad application prospects in spintronics and valleytronics. However, there are still many problems waiting to be solved on the way to practical application.展开更多
Twist-angle two-dimensional systems,such as twisted bilayer graphene,twisted bilayer transition metal dichalcogenides,twisted bilayer phosphorene and their multilayer van der Waals heterostructures,exhibit novel and t...Twist-angle two-dimensional systems,such as twisted bilayer graphene,twisted bilayer transition metal dichalcogenides,twisted bilayer phosphorene and their multilayer van der Waals heterostructures,exhibit novel and tunable properties due to the formation of Moirésuperlattice and modulated Moirébands.The review presents a brief venation on the development of"twistronics"and subsequent applications based on band engineering by twisting.Theoretical predictions followed by experimental realization of magic-angle bilayer graphene ignited the flame of investigation on the new freedom degree,twistangle,to adjust(opto)electrical behaviors.Then,the merging of Dirac cones and the presence of flat bands gave rise to enhanced light-matter interaction and gate-dependent electrical phases,respectively,leading to applications in photodetectors and superconductor electronic devices.At the same time,the increasing amount of theoretical simulation on extended twisted 2D materials like TMDs and BPs called for further experimental verification.Finally,recently discovered properties in twisted bilayer h-BN evidenced h-BN could be an ideal candidate for dielectric and ferroelectric devices.Hence,both the predictions and confirmed properties imply twist-angle two-dimensional superlattice is a group of promising candidates for next-generation(opto)electronics.展开更多
Nonlinear optoelectronic responses play a crucial role not only in optical devices but also in probing the fundamental properties of quantum materials. The recently discovered Weyl semimetals, belonging to the class o...Nonlinear optoelectronic responses play a crucial role not only in optical devices but also in probing the fundamental properties of quantum materials. The recently discovered Weyl semimetals, belonging to the class of topological metallic phases, provide an ideal platform to explore the physical effects that relate to topology in gapless materials.展开更多
A magnetic semiconductor whose electronic charge and spin can be regulated together will be an important compon-ent of future spintronic devices.Here,we construct a two-dimensional(2D)Fe doped SnS_(2)(Fe-SnS_(2))homog...A magnetic semiconductor whose electronic charge and spin can be regulated together will be an important compon-ent of future spintronic devices.Here,we construct a two-dimensional(2D)Fe doped SnS_(2)(Fe-SnS_(2))homogeneous junction and investigate its electromagnetic transport feature.The Fe-SnS_(2) homojunction device showed large positive and unsatur-ated magnetoresistance(MR)of 1800%in the parallel magnetic field and 600%in the vertical magnetic field,indicating an obvi-ous anisotropic MR feature.In contrast,The MR of Fe-SnS_(2) homojunction is much larger than the pure diamagnetic SnS_(2) and most 2D materials.The application of a gate voltage can regulate the MR effect of Fe-SnS_(2) homojunction devices.Moreover,the stability of Fe-SnS_(2) in air has great application potential.Our Fe-SnS_(2) homojunction has a significant potential in future mag-netic memory applications.展开更多
Copper(Cu)-based materials(such as cuprates,Cu chalcogenides,and Cu halides)often exhibit unusual properties such as superconductivity,ultralow thermal conductivity,and superionicity.However,the electronic origin of t...Copper(Cu)-based materials(such as cuprates,Cu chalcogenides,and Cu halides)often exhibit unusual properties such as superconductivity,ultralow thermal conductivity,and superionicity.However,the electronic origin of these unusual behaviors remains elusive.In this study,we demonstrate that the high-lying occupied 3d orbital of Cu causes a strong s-d coupling with its unoccupied 4s state when local symmetry is reduced.This leads to strong phonon anharmonicity and is responsible for these intriguing properties.For example,during thermal transport,symmetry-controlled s-d coupling can substantially lower the lattice potential barrier,thereby enhancing the anharmonicity and scattering between phonons and ultimately significantly reducing lattice thermal conductivity.We confirmed this understanding with Raman spectra measurements,which demonstrated a remarkable red shift in the phonon vibrational frequency with an increase in the temperature of Cu-based semiconductors.Our study shows that the cause of phonon anharmonicity is related to the fundamental electronic structures,which can also explain other unusual physical properties of the Cu compounds.展开更多
Van der Waals (vdW) heterojunctions are equipped to avert dangling bonds due to weak, inter-layer vdW force, and ensure strong in-plane covalent bonding for two-dimensional layered structures. We fabricated four het...Van der Waals (vdW) heterojunctions are equipped to avert dangling bonds due to weak, inter-layer vdW force, and ensure strong in-plane covalent bonding for two-dimensional layered structures. We fabricated four heterojunctions devices of different layers based on p-type distorted 1T-MX2 ReSe2 and n-type hexagonal MoS2 nanoflakes, and measured their electronic and optoelectronic properties. The device showed a high rectification coefficient of 500 for the diode, a high ON/OFF ratio and higher electron mobility for the field-effect transistor (FET) compared with the individual components, and a high current responsivity (Rλ) and external quantum efficiency (EQE) of 6.75 A/W and 1,266%, respectively, for the photodetector.展开更多
Doping, which is the intentional introducti on of impurities into a material, can improve the metal-semiconductor interface by reducing Schottky barrier width. Here, we prese nt high-quality two-dime nsional SnS2 nano...Doping, which is the intentional introducti on of impurities into a material, can improve the metal-semiconductor interface by reducing Schottky barrier width. Here, we prese nt high-quality two-dime nsional SnS2 nano sheets with well-controlled Sb dopi ng concen tration via direct vapor growth approach and following micromechanical cleavage process. X-ray photoelectro n spectroscopy (XPS) measureme nt dem on strates that Sb contents of the doped samples are approximately 0.22%, 0.34% and 1.21%, respectively, and doping in duces the upward shift of the Fermi level with respect to the pristi ne SnS2. Tran smissio n electro n microscopy (TEM) characterizatio n exhibits that Sb-doped SnS2 nano sheets have a high-quality hexagonal symmetry structure and Sb element is uniformly distributed in the nano sheets. The phototra nsistors based on the Sb-doped SnS2 mono layers show n-type behavior with high mobility which is one order of magn itude higher than that of pristi ne SnS2 phototra nsistors. The photorespo nsivity and exter nal quantum efficiency (EQE) of Sb-S nS2 mono layers phototra nsistors are approximately three orders of magnitude higher than that of pristine SnS2 phototransistor. The results suggest that the method of reducing Shottky barrier width to achieve high mobility and photoresp on sivity is effective, and Sb-doped SnS2 mono layer has significant potential in future nanoelectronic and optoelectronic applications.展开更多
Traditional methods of discovering new materials,such as the empirical trial and error method and the density functional theory(DFT)-based method,are unable to keep pace with the development of materials science today...Traditional methods of discovering new materials,such as the empirical trial and error method and the density functional theory(DFT)-based method,are unable to keep pace with the development of materials science today due to their long development cycles,low efficiency,and high costs.Accordingly,due to its low computational cost and short development cycle,machine learning is coupled with powerful data processing and high prediction performance and is being widely used in material detection,material analysis,and material design.In this article,we discuss the basic operational procedures in analyzing material properties via machine learning,summarize recent applications of machine learning algorithms to several mature fields in materials science,and discuss the improvements that are required for wide-ranging application.展开更多
Low-dimensional(including two-dimensional[2D],one-dimensional[1D],and zero-dimensional[0D])semiconductor materials have great potential in electronic/optoelectronic applications due to their unique structure and chara...Low-dimensional(including two-dimensional[2D],one-dimensional[1D],and zero-dimensional[0D])semiconductor materials have great potential in electronic/optoelectronic applications due to their unique structure and characteristics.Many 2D(such as transition metal dichalcogenides and black phosphorus)and 1D(such as NWs)materials have demonstrated superior performance in field effect transistors,photodetectors(PDs),and some flexible devices.And in some hybrid structures of 0D materials and 1D or 2D materials,the modification of 1D and 2D devices by 0D materials is embodied.This type of hybrid heterostructure has a larger performance optimization compared with the original.In the application of PDs,the variety of lowdimensional materials and properties enable wide-spectrum detection from ultraviolet UV to infrared,which provide a potential option for PDs under various conditions.For flexible electronic devices,high performance and mechanical stability are two important features.Low-dimensional materials offer unparalleled advantages in flexible devices.In this review,we will focus on the various low-dimensional materials that have been extensively studied and their applications in the electronics/optoelectronic and flexible electronics.From the composition and lattice structure of materials(including alloys)to the construction of various devices and heterostructures,we will introduce their application and recent development under various conditions.These works can provide valuable guidance for the construction and application of more highperformance and multifunctional devices.展开更多
基金supported by National Natural Science Foundation of China(51672308,51972025,61888102,and 62004187).
文摘Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)photodetector.Here,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene based flexible NIR photodetector array via a facile photolithography technology.The single ZnSb/Ti_(3)C_(2)T_(x)photodetector exhibited a high light-to-dark current ratio of 4.98,fast response/recovery time(2.5/1.3 s)and excellent stability due to the tight connection between 2D ZnSb nanoplates and 2D Ti_(3)C_(2)T_(x)MXene nanoflakes,and the formed 2D van der Waals heterojunction.Thin polyethylene terephthalate(PET)substrate enables the ZnSb/Ti_(3)C_(2)T_(x)photodetector withstand bending such that stable photoelectrical properties with non-obvious change were maintained over 5000 bending cycles.Moreover,the ZnSb/Ti_(3)C_(2)T_(x)photodetectors were integrated into a 26×5 device array,realizing a NIR image sensing application.
文摘Twisted van der Waals heterostructures are becoming the building blocks for engineering new device structures, in which their electronic, optical and mechanical properties can be tuned by changing the “twist” angle between layers of 2D materials. Such twisted 2D heterostructures offer a unique opportunity to create a new field of “twistronics” by mechanically stacking different 2D van der Waals materials together.
文摘There is currently great optimism within the electronics community that gallium oxide(Ga_(2)O_(3)) ultra-wide bandgap semiconductors have unprecedented prospects for eventually revolutionizing a rich variety of power electronic applications. Specially, benefiting from its ultra-high bandgap of around 4.8 eV, it is expected that the emerging Ga_(2)O_(3) technology would offer an exciting platform to deliver massively enhanced device performance for power electronics and even completely new applications.
文摘Gallium oxide(Ga_(2)O_(3))has garnered world-wide atten-tion as an ultrawide-bandgap semiconductor material from the area of power electronics and DUV optical devices benefit-ing from its outstanding electronic and optoelectronic proper-ties.For one thing,since Ga_(2)O_(3)features high critical break-down field of 8 MV/cm and Baliga’s figure of merit(BFOM)of 3444,it is a promising candidate for advanced high-power applications.For another thing,due to the bandgap directly corresponding to the deep-ultraviolet(DUV)region,Ga_(2)O_(3)is widely used in DUV optoelectronic devices.
文摘Research on two-dimensional(2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since the mechanical exfoliation of graphene in 2004. Starting from graphene, 2D materials now have become a big family with numerous members and diverse categories. The unique structural features and physicochemical properties of 2D materials make them one class of the most appealing candidates for a wide range of potential applications. In particular, we have seen some major breakthroughs made in the field of 2D materials in last five years not only in developing novel synthetic methods and exploring new structures/properties but also in identifying innovative applications and pushing forward commercialisation. In this review, we provide a critical summary on the recent progress made in the field of 2D materials with a particular focus on last five years. After a brief backgroundintroduction, we first discuss the major synthetic methods for 2D materials, including the mechanical exfoliation, liquid exfoliation, vapor phase deposition, and wet-chemical synthesis as well as phase engineering of 2D materials belonging to the field of phase engineering of nanomaterials(PEN). We then introduce the superconducting/optical/magnetic properties and chirality of 2D materials along with newly emerging magic angle 2D superlattices. Following that, the promising applications of 2D materials in electronics, optoelectronics, catalysis, energy storage, solar cells, biomedicine, sensors, environments, etc. are described sequentially. Thereafter, we present the theoretic calculations and simulations of 2D materials. Finally, after concluding the current progress, we provide some personal discussions on the existing challenges and future outlooks in this rapidly developing field.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 61622406, 61571415, 11874350, 11434010)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB30000000)
文摘Two-dimensional(2D) anisotropic materials, such as B-P, B-As, GeSe, GeAs, ReSe2, KP15 and their hybrid systems, exhibit unique crystal structures and extraordinary anisotropy. This review presents a comprehensive comparison of various 2D anisotropic crystals as well as relevant FETs and photodetectors, especially on their particular anisotropy in optical and electrical properties. First, the structure of typical 2D anisotropic crystal as well as the analysis of structural anisotropy is provided. Then, recent researches on anisotropic Raman spectra are reviewed. Particularly, a brief measurement principle of Raman spectra under three typical polarized measurement configurations is introduced. Finally, recent progress on the electrical and photoelectrical properties of FETs and polarization-sensitive photodetectors based on 2D anisotropic materials is summarized for the comparison between different 2D anisotropic materials. Beyond the high response speed, sensitivity and on/off ratio, these 2D anisotropic crystals exhibit highly conduction ratio and dichroic ratio which can be applied in terms of polarization sensors, polarization spectroscopy imaging, optical radar and remote sensing.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61571415 and 61622406)the National Key Research and Development Program of China(Grant No.2017YFA0207500)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB30000000)Beijing Academy of Quantum Information Sciences,China(Grant No.Y18G04)
文摘Two-dimensional(2D) magnetic crystals have attracted great attention due to their emerging new physical phenomena. They provide ideal platforms to study the fundamental physics of magnetism in low dimensions. In this research,magnetic tunneling junctions(MTJs) based on XSe2(X = Mn, V) with room-temperature ferromagnetism were studied using first-principles calculations. A large tunneling magnetoresistance(TMR) of 725.07% was obtained in the MTJs based on monolayer MnSe2. Several schemes were proposed to improve the TMR of these devices. Moreover, the results of our non-equilibrium transport calculations showed that the large TMR was maintained in these devices under a finite bias.The transmission spectrum was analyzed according to the orbital components and the electronic structure of the monolayer XSe2(X = Mn, V). The results in this paper demonstrated that the MTJs based on a 2D ferromagnet with room-temperature ferromagnetism exhibited reliable performance. Therefore, such devices show the possibility for potential applications in spintronics.
文摘In recent years,low-dimensional materials especially 2D materials have attracted wide attention due to their novel proprieties.Plenty of devices with excellent performance have been made for different applications basing on 2D materials.In order to further explore the advantages of 2D materials and integrating them into semiconductor fabrication lines,the 2D material/Si heterostructure-based photodetectors played important roles in many different domains due to their price advantage,mature manufacturing craft and good compatibility to integrated circuits.
文摘With the rapid development of mobile Internet and intelligent devices,flexible electronic technology has attracted wide attention driven by the huge demand of the market.As one type of flexible electronic devices,flexible sensors have attracted great interest because of their promising prospects in artificial intelligence,medical health,and environmental protection.In recent years,flexible sensors with high sensitivity,selectivity,good deformability,reliable stability,and portability are urgently needed to meet the developments of artificial skin,human-computer interaction,point of care diagnostics and wearable electronic devices.
文摘Since the successful fabrication of two-dimensional (2D) ferromagnetic (FM) monolayer CrI3 and Cr2Ge2Te6, 2D FM materials are becoming an exciting research topic in condensed matter physics and materials fields, as they provide a good platform to explore the fundamental physical properties of magnetic materials under 2D limit. In this review, we summarize the theoretical research progress of intrinsic 2D FM materials and related van der Waals heterostructures (vdWHs) including their electronic structures, magnetism, Curie temperature, valley polarization, and band alignment. Moreover, we also summarize recent researches on the methods that used to regulate the above properties of 2D FM materials and vdWHs, such as defects, doping, strain, electric field and interlayer coupling. These studies show that 2D FM materials have broad application prospects in spintronics and valleytronics. However, there are still many problems waiting to be solved on the way to practical application.
基金financially supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB43000000)the CAS-JSPS Cooperative Research Project(No.GJHZ2021131)。
文摘Twist-angle two-dimensional systems,such as twisted bilayer graphene,twisted bilayer transition metal dichalcogenides,twisted bilayer phosphorene and their multilayer van der Waals heterostructures,exhibit novel and tunable properties due to the formation of Moirésuperlattice and modulated Moirébands.The review presents a brief venation on the development of"twistronics"and subsequent applications based on band engineering by twisting.Theoretical predictions followed by experimental realization of magic-angle bilayer graphene ignited the flame of investigation on the new freedom degree,twistangle,to adjust(opto)electrical behaviors.Then,the merging of Dirac cones and the presence of flat bands gave rise to enhanced light-matter interaction and gate-dependent electrical phases,respectively,leading to applications in photodetectors and superconductor electronic devices.At the same time,the increasing amount of theoretical simulation on extended twisted 2D materials like TMDs and BPs called for further experimental verification.Finally,recently discovered properties in twisted bilayer h-BN evidenced h-BN could be an ideal candidate for dielectric and ferroelectric devices.Hence,both the predictions and confirmed properties imply twist-angle two-dimensional superlattice is a group of promising candidates for next-generation(opto)electronics.
文摘Nonlinear optoelectronic responses play a crucial role not only in optical devices but also in probing the fundamental properties of quantum materials. The recently discovered Weyl semimetals, belonging to the class of topological metallic phases, provide an ideal platform to explore the physical effects that relate to topology in gapless materials.
基金financially supported by the National Key Research and Development Program of China (Grant No. 2017YFA0207500)the National Natural Science Foundation of China (Grant No. 62125404)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB43000000)
文摘A magnetic semiconductor whose electronic charge and spin can be regulated together will be an important compon-ent of future spintronic devices.Here,we construct a two-dimensional(2D)Fe doped SnS_(2)(Fe-SnS_(2))homogeneous junction and investigate its electromagnetic transport feature.The Fe-SnS_(2) homojunction device showed large positive and unsatur-ated magnetoresistance(MR)of 1800%in the parallel magnetic field and 600%in the vertical magnetic field,indicating an obvi-ous anisotropic MR feature.In contrast,The MR of Fe-SnS_(2) homojunction is much larger than the pure diamagnetic SnS_(2) and most 2D materials.The application of a gate voltage can regulate the MR effect of Fe-SnS_(2) homojunction devices.Moreover,the stability of Fe-SnS_(2) in air has great application potential.Our Fe-SnS_(2) homojunction has a significant potential in future mag-netic memory applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174099,61922077,11874347,12088101,11991060U2230402)+3 种基金the National Key Research and Development Program of China(Grant Nos.2018YFB2200100,and 2020YFB1506400)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB22)the Beijing Science and Technology Committee(Grant No.Z181100005118003)supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.Y2021042)。
文摘Copper(Cu)-based materials(such as cuprates,Cu chalcogenides,and Cu halides)often exhibit unusual properties such as superconductivity,ultralow thermal conductivity,and superionicity.However,the electronic origin of these unusual behaviors remains elusive.In this study,we demonstrate that the high-lying occupied 3d orbital of Cu causes a strong s-d coupling with its unoccupied 4s state when local symmetry is reduced.This leads to strong phonon anharmonicity and is responsible for these intriguing properties.For example,during thermal transport,symmetry-controlled s-d coupling can substantially lower the lattice potential barrier,thereby enhancing the anharmonicity and scattering between phonons and ultimately significantly reducing lattice thermal conductivity.We confirmed this understanding with Raman spectra measurements,which demonstrated a remarkable red shift in the phonon vibrational frequency with an increase in the temperature of Cu-based semiconductors.Our study shows that the cause of phonon anharmonicity is related to the fundamental electronic structures,which can also explain other unusual physical properties of the Cu compounds.
基金This work was supported by the "Hundred Talents Program" of Chinese Academy of Sciences (CAS),the National Natural Science Foundation of China (No. 91233120), and the CAS/SAFEA International Partnership Program for Creative Research Teams.
文摘Van der Waals (vdW) heterojunctions are equipped to avert dangling bonds due to weak, inter-layer vdW force, and ensure strong in-plane covalent bonding for two-dimensional layered structures. We fabricated four heterojunctions devices of different layers based on p-type distorted 1T-MX2 ReSe2 and n-type hexagonal MoS2 nanoflakes, and measured their electronic and optoelectronic properties. The device showed a high rectification coefficient of 500 for the diode, a high ON/OFF ratio and higher electron mobility for the field-effect transistor (FET) compared with the individual components, and a high current responsivity (Rλ) and external quantum efficiency (EQE) of 6.75 A/W and 1,266%, respectively, for the photodetector.
基金the National Natural Science Foundation of China (Nos. 61804050, 51872086, 61622406, 11674310, and 61571415)the Double First-Class Initiative of Hunan University (No. 531109100004)the Fundamental Research Funds of the Central Universities (Nos. 531107051078 and 531107051055).
文摘Doping, which is the intentional introducti on of impurities into a material, can improve the metal-semiconductor interface by reducing Schottky barrier width. Here, we prese nt high-quality two-dime nsional SnS2 nano sheets with well-controlled Sb dopi ng concen tration via direct vapor growth approach and following micromechanical cleavage process. X-ray photoelectro n spectroscopy (XPS) measureme nt dem on strates that Sb contents of the doped samples are approximately 0.22%, 0.34% and 1.21%, respectively, and doping in duces the upward shift of the Fermi level with respect to the pristi ne SnS2. Tran smissio n electro n microscopy (TEM) characterizatio n exhibits that Sb-doped SnS2 nano sheets have a high-quality hexagonal symmetry structure and Sb element is uniformly distributed in the nano sheets. The phototra nsistors based on the Sb-doped SnS2 mono layers show n-type behavior with high mobility which is one order of magn itude higher than that of pristi ne SnS2 phototra nsistors. The photorespo nsivity and exter nal quantum efficiency (EQE) of Sb-S nS2 mono layers phototra nsistors are approximately three orders of magnitude higher than that of pristine SnS2 phototransistor. The results suggest that the method of reducing Shottky barrier width to achieve high mobility and photoresp on sivity is effective, and Sb-doped SnS2 mono layer has significant potential in future nanoelectronic and optoelectronic applications.
基金funded by China Postdoctoral Science Foundation(no.2017M620694)National Postdoctoral Program for Innovative Talents(BX201700040)+3 种基金supported by the National Natural Science Foundation of China(grant nos.61622406 and 61571415)the National Key Research and Development Program of China(grant nos.2017YFA0207500 and 2016YFB0700700)the Strategic Priority Research Program of Chinese Academy of Sciences(grant no.XDB30000000)Beijing Academy of Quantum Information Sciences(grant no.Y18G04).
文摘Traditional methods of discovering new materials,such as the empirical trial and error method and the density functional theory(DFT)-based method,are unable to keep pace with the development of materials science today due to their long development cycles,low efficiency,and high costs.Accordingly,due to its low computational cost and short development cycle,machine learning is coupled with powerful data processing and high prediction performance and is being widely used in material detection,material analysis,and material design.In this article,we discuss the basic operational procedures in analyzing material properties via machine learning,summarize recent applications of machine learning algorithms to several mature fields in materials science,and discuss the improvements that are required for wide-ranging application.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.61622406,61571415,61625404,61888102)the National Key Research and Development Program of China(Grant No.2017YFA0207500,2016YFB0700700)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB30000000)the Beijing Academy of Quantum Information Sciences(Grant No.Y18G04).
文摘Low-dimensional(including two-dimensional[2D],one-dimensional[1D],and zero-dimensional[0D])semiconductor materials have great potential in electronic/optoelectronic applications due to their unique structure and characteristics.Many 2D(such as transition metal dichalcogenides and black phosphorus)and 1D(such as NWs)materials have demonstrated superior performance in field effect transistors,photodetectors(PDs),and some flexible devices.And in some hybrid structures of 0D materials and 1D or 2D materials,the modification of 1D and 2D devices by 0D materials is embodied.This type of hybrid heterostructure has a larger performance optimization compared with the original.In the application of PDs,the variety of lowdimensional materials and properties enable wide-spectrum detection from ultraviolet UV to infrared,which provide a potential option for PDs under various conditions.For flexible electronic devices,high performance and mechanical stability are two important features.Low-dimensional materials offer unparalleled advantages in flexible devices.In this review,we will focus on the various low-dimensional materials that have been extensively studied and their applications in the electronics/optoelectronic and flexible electronics.From the composition and lattice structure of materials(including alloys)to the construction of various devices and heterostructures,we will introduce their application and recent development under various conditions.These works can provide valuable guidance for the construction and application of more highperformance and multifunctional devices.
基金supported by the National Key R&D Program of China (2017YFA0303400 and 2017YFB0405700)the National Natural Science foundation of China (61774144)+2 种基金Beijing Natural Science Foundation Key Program (Z190007)the Project from Chinese Academy of Sciences (QYZDY-SSW-JSC020, XDPB12, and XDB28000000)K C Wong Education Foundation。