The development of two-dimensional(2D)semiconductors has attracted widespread attentions in the scientific community and industry due to their ultra-thin thickness,unique structure,excellent optoelectronic properties ...The development of two-dimensional(2D)semiconductors has attracted widespread attentions in the scientific community and industry due to their ultra-thin thickness,unique structure,excellent optoelectronic properties and novel physics.The excellent flexibility and outstanding mechanical strength of 2D semiconductors provide opportunities for fabricated strain-sensitive devices and utilized strain tuning their electronic and optic–electric performance.The strain-engineered one-dimensional materials have been well investigated,while there is a long way to go for 2D semiconductors.In this review,starting with the fundamental theories of piezoelectric and piezoresistive effect resulted by strain,following we reviewed the recent simulation works of strain engineering in novel 2D semiconductors,such as Janus 2D and 2D-Xene structures.Moreover,recent advances in experimental observation of strain tuning PL spectra and transport behavior of 2D semiconductors are summarized.Furthermore,the applications of strain-engineered 2D semiconductors in sensors,photodetectors and nanogenerators are also highlighted.At last,we in-depth discussed future research directions of strain-engineered 2D semiconductor and related electronics and optoelectronics device applications.展开更多
The discovery of 2D organic semiconductors of atomically thin structures has attracted great attention due to their emerging optical, electronic, optoelectronic and mechatronic properties. Recent progress in such orga...The discovery of 2D organic semiconductors of atomically thin structures has attracted great attention due to their emerging optical, electronic, optoelectronic and mechatronic properties. Recent progress in such organic nanostructures has opened new opportunities for engineering material properties in many ways, such as, 0D/1D/2D nanoparticles hybridization, strain engineering, atomic doping etc. Moreover, 2D organic nanostructures exhibit a unique feature of bio–functionality and are highly sensitive to bio-analytes. Such peculiar behavior in 2D organics can be utilized to design highly-efficient bio-sensors. Also, a bio-molecular integrated electronic/optoelectronic device with enhanced performance can be attained. Furthermore, the bio-degradable, biocompatible, biometabolizable, non-toxic behaviour and natural origin of organic nanomaterials can address the current ecological concerns of increasing inorganic material based electronic waste. This review highlights the benefits of 2D organic semiconductors. Considering the importance of strategic techniques for growing thin 2D organic layers,this review summarizes progress towards this direction. The possible challenges for long-time stability and future research directions in 2D organic nano electronics/optoelectronics are also discussed. We believe that this review article provides immense research interests in organic 2D nanotechnology for exploiting green technologies in the future.展开更多
We investigate two-photon transitions to the electron-hole scattering continuum in monolayer transition-metal dichalcogenides, and identify two contributions to this nonlinear optical process with opposite circularly ...We investigate two-photon transitions to the electron-hole scattering continuum in monolayer transition-metal dichalcogenides, and identify two contributions to this nonlinear optical process with opposite circularly polarized valley selection rules. In the non-interacting limit, the competition between the two contributions leads to a crossover of the selection rule with the increase of the two-photon energy. With the strong Coulomb interaction between the electron and hole, the two contributions excite electron-hole scattering states in orthogonal angular momentum channels, while the strength of the transition can be substantially enhanced by the interaction. Based on this picture of the two-photon transition, the second harmonic generation(SHG) in the electron-hole continuum is analyzed, where the Coulomb interaction is shown to greatly alter the relative strength of different cross-circular polarized SHG processes. Valley current injection by the quantum interference of one-photon and two-photon transition is also investigated in the presence of the strong Coulomb interaction, which significantly enhances the injection rate.展开更多
Atomically thin two-dimensional （2D） layered materials have potential applications in nanoelectronics, nanophoton- ics, and integrated optoelectronics. Band gap engineering of these 2D semiconductors is critical for...Atomically thin two-dimensional （2D） layered materials have potential applications in nanoelectronics, nanophoton- ics, and integrated optoelectronics. Band gap engineering of these 2D semiconductors is critical for their broad applications in high-performance integrated devices, such as broad-band photodetectors, multi-color light emitting diodes （LEDs）, and high-efficiency photovoltaic devices. In this review, we will summarize the recent progress on the controlled growth of composition modulated atomically thin 2D semiconductor alloys with band gaps tuned in a wide range, as well as their induced applications in broadly tunable optoelectronic components. The band gap engineered 2D semiconductors could open up an exciting opportunity for probing their fundamental physical properties in 2D systems and may find diverse applications in functional electronic/optoelectronic devices.展开更多
Elemental doping confined in atomically-thin 2 D semiconductors offers a compelling strategy for constructing high performance photocatalysts.Although impressive progress has been achieved based on co-thermolysis meth...Elemental doping confined in atomically-thin 2 D semiconductors offers a compelling strategy for constructing high performance photocatalysts.Although impressive progress has been achieved based on co-thermolysis method,the choices of dopants as well as semiconductor hosts are still quite limited to yield the elaborate photocatalyst with atomic-layer-confined doping defects,owing to the difficulty in balancing the reaction kinetics of different precursors.This study shows that the cation exchange reaction,which is dictated by the Pearson's hard and soft acids and bases(HSAB)theory and allowed to proceed at mild temperatures,can be developed into a conceptually new protocol for engineering elemental doping confined in semiconductor atomic layers.To this aim,the two atomic layers of a new type of 2 D photocatalyst PdSe0_(3)(PdSe0_(3)2 ALs,1.1 nm)are created by liquid exfoliation and exploited as a proof-of-concept prototype.It is demonstrated that the Mn(Ⅱ)dopants with controlled concentrations can be incorporated into PdSeO_(3)2 ALs via topological Mn^(2+) for-Pd^(2+) cation exchange performed in water/isopropanol solution at 30℃.The resulting Mn-doped PdSeO_(3)2 ALs present enhanced capacity for driving photocatalytic oxidation reactions in comparison with their undoped counterparts.The findings here suggest that the new route mediated by post synthetic cation exchange promises to give access to manifold 2 D confined-doping photocatalysts,with little perturbations on the thickness,morphology,and crystal structure of the atomically-thin semiconductor hosts.展开更多
The interplay of magnetic and semiconducting properties has been in the focus for more than a half of the century. In this introductory article we briefly review the key properties and functionalities of various magne...The interplay of magnetic and semiconducting properties has been in the focus for more than a half of the century. In this introductory article we briefly review the key properties and functionalities of various magnetic semiconductor families, including europium chalcogenides, chromium spinels, dilute magnetic semiconductors, dilute ferromagnetic semiconductors and insulators, mentioning also sources of non-uniformities in the magnetization distribution, accounting for an apparent high Curie temperature ferromagnetism in many systems. Our survey is carried out from today's perspective of ferromagnetic and antiferromagnetic spintronics as well as of the emerging fields of magnetic topological materials and atomically thin 2D layers.展开更多
Currently,the development of high-efficiency two-dimensional(2D)transistors is still hindered by the limited availability of suitable semiconductors and the contact resistance between the metal contact and the 2D semi...Currently,the development of high-efficiency two-dimensional(2D)transistors is still hindered by the limited availability of suitable semiconductors and the contact resistance between the metal contact and the 2D semiconductors.Endeavors to address these challenges are highly desired.In this study,we conducted a comprehensive exploration of the potential 2D transition metal dinitrides(TMN_(2)s,TM=all the 3d,4d and 5d transition metals)with hexagonal(h-)and trigonal(t-)phases through systematic first-principles calculations.Among all h-TMN_(2)s and t-TMN_(2)s structures,we identified 8 TMN_(2)s that exhibit dynamical and thermal stability at room temperature.Of these,the h-TiN_(2),h-ZrN_(2)and h-HfN_(2)arefound to be semiconductors,and their direct bang gap,calculated at the HSE06 level,are 1.48,1.96 and 2.64 eV,respectively.The electron and hole mobility(μ_(e)andμ_(h))of these three structures exceed 1×10^(4)and1×10^(3)cm^(2)·V^(-1)·s^(-1),respectively.Especially,theμeof h-TiN_(2)amounts to 2.5×10^(4)cm^(2)·V^(-1)·s^(-1),and theμhof h-ZrN_(2)reaches to 7.7×10^(3)cm^(2)·V^(-1)·s^(-1).Importantly,unlike the MoS_(2)system,h-TMN_(2)forms Ohm contacts with both transition metals(e.g.,Cu)and 2D metals(e.g.,graphene),with tunneling possibilities exceeding 50%in the Cu system.These outstanding intrinsic semiconductor properties and contact characteristics exhibited by h-TMN_(2)highlight the immense potential of transition metal dinitrides in driving the advancement of next-generation information devices.Our findings significantly broaden the range of 2D materials and provide valuable insights for the development of high-eficiency 2D information devices.展开更多
Intrinsic two-dimensional(2D)ferromagnetic(FM)semiconductors have attracted extensive attentions for their potential applications in next-generation spintronics devices.In recent years,the van der Waals material VI_(3...Intrinsic two-dimensional(2D)ferromagnetic(FM)semiconductors have attracted extensive attentions for their potential applications in next-generation spintronics devices.In recent years,the van der Waals material VI_(3) has been experimentally found to be an intrinsic FM semiconductor.However,the electronic structure of the VI_(3) is not fully understood.To reveal why the VI_(3)is a ferromagnetic semiconductor with strong out-of-plane anisotropy,we systematically studied the electronic structure of the monolayer VI_(3).Our results confirm that the monolayer VI_(3) is a Mott insulator,and d^(2) electrons occupy a_(g) and e_(g)^(π+) orbitals.The half-metallic state is a metastable state with a total energy 0.7 e V higher than the ferromagnetic Mott insulating state.Furthermore,our study confirmed that the VI_(3)exhibits the out-of-plane magnetic anisotropy,which originates from d^(2) electrons occupying low-lying agand egπ+orbitals.Since the orbital angular momentum of the e_(g)^(π+) state is not completely quenched,the VI_(3) has the out-of-plane anisotropy under interplay between the spin-orbit coupling and crystal field.Our study provides valuable guidance for the design of 2D magnetic materials with pronounced out-of-plane anisotropy.展开更多
As a class of metal-free two-dimensional(2D)semiconductor materials,polymeric carbon nitrides have attracted wide attention recently due to its facile regulation of the molecular and electronic structures,availability...As a class of metal-free two-dimensional(2D)semiconductor materials,polymeric carbon nitrides have attracted wide attention recently due to its facile regulation of the molecular and electronic structures,availability in abundance and high stability.According to the different ratios of C and N atoms in the fra mework,a series of C_(x)N_(y)materials have been successfully synthesized by virtue of various precursors,which further triggers extensive investigations of broad applications ranging from sustainable photocatalytic reactions and highly sensitive optoelectronic biosensing.In view of topological structures on their electronic structures and material properties,the as-reported C_(x)N_(y)could be generally classified into two main categories with three-or six-bond-extending frameworks.Owing to the effective n→π*transition in most C_(x)N_(y)materials,the relative energy level of the lone-pair electrons on N atoms is high,which thus endows the mate rials with the capability of visible light absorption.Meanwhile,the different repeating units,bridging groups and defect sites of these two kinds of C_(x)N_(y)allow them to effectively drive a diverse of promising applications that require specific electronic,inte rfacial and geometric properties.This review paper aims to summarize the recent progress in topological structure design and the relevant electronic band structures and striking properties of C_(x)N_(y)materials,In the final part,we also discuss the existing challenges of C_(x)N_(y)and outlook the prospect possibilities.展开更多
The design and preparation of novel quantum materials with atomic precision are crucial for exploring new physics and for device applications.Electron irradiation has been demonstrated as an effective method for prepa...The design and preparation of novel quantum materials with atomic precision are crucial for exploring new physics and for device applications.Electron irradiation has been demonstrated as an effective method for preparing novel quantum materials and quantum structures that could be challenging to obtain otherwise.It features the advantages of precise control over the patterning of such new materials and their integration with other materials with different functionalities.Here,we present a new strategy for fabricating freestanding monolayer SiC within nanopores of a graphene membrane.By regulating the energy of the incident electron beam and the in-situ heating temperature in a scanning transmission electron microscope(STEM),we can effectively control the patterning of nanopores and subsequent growth of monolayer SiC within the graphene lattice.The resultant SiC monolayers seamlessly connect with the graphene lattice,forming a planar structure distinct by a wide direct bandgap.Our in-situ STEM observations further uncover that the growth of monolayer SiC within the graphene nanopore is driven by a combination of bond rotation and atom extrusion,providing new insights into the atom-by-atom self-assembly of freestanding two-dimensional(2D)monolayers.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
基金supported by the National Natural Science Foundation of China(51572025,51627801,61435010 and 51702219)the State Key Research Development Program of China(2019YFB2203503)+3 种基金Guangdong Basic and Applied Basic Research Foundation(2019A1515110209)the Science and Technology Innovation Commission of Shenzhen(JCYJ20170818093453105,JCYJ20180305125345378)National Foundation of China(41422050303)Beijing Municipal Science&Technology Commission and the Fundamental Research Funds for Central Universities.
文摘The development of two-dimensional(2D)semiconductors has attracted widespread attentions in the scientific community and industry due to their ultra-thin thickness,unique structure,excellent optoelectronic properties and novel physics.The excellent flexibility and outstanding mechanical strength of 2D semiconductors provide opportunities for fabricated strain-sensitive devices and utilized strain tuning their electronic and optic–electric performance.The strain-engineered one-dimensional materials have been well investigated,while there is a long way to go for 2D semiconductors.In this review,starting with the fundamental theories of piezoelectric and piezoresistive effect resulted by strain,following we reviewed the recent simulation works of strain engineering in novel 2D semiconductors,such as Janus 2D and 2D-Xene structures.Moreover,recent advances in experimental observation of strain tuning PL spectra and transport behavior of 2D semiconductors are summarized.Furthermore,the applications of strain-engineered 2D semiconductors in sensors,photodetectors and nanogenerators are also highlighted.At last,we in-depth discussed future research directions of strain-engineered 2D semiconductor and related electronics and optoelectronics device applications.
基金financial support from National Science Foundation China (No. 61775147)Australian Research Council (ARC) No. DP180103238
文摘The discovery of 2D organic semiconductors of atomically thin structures has attracted great attention due to their emerging optical, electronic, optoelectronic and mechatronic properties. Recent progress in such organic nanostructures has opened new opportunities for engineering material properties in many ways, such as, 0D/1D/2D nanoparticles hybridization, strain engineering, atomic doping etc. Moreover, 2D organic nanostructures exhibit a unique feature of bio–functionality and are highly sensitive to bio-analytes. Such peculiar behavior in 2D organics can be utilized to design highly-efficient bio-sensors. Also, a bio-molecular integrated electronic/optoelectronic device with enhanced performance can be attained. Furthermore, the bio-degradable, biocompatible, biometabolizable, non-toxic behaviour and natural origin of organic nanomaterials can address the current ecological concerns of increasing inorganic material based electronic waste. This review highlights the benefits of 2D organic semiconductors. Considering the importance of strategic techniques for growing thin 2D organic layers,this review summarizes progress towards this direction. The possible challenges for long-time stability and future research directions in 2D organic nano electronics/optoelectronics are also discussed. We believe that this review article provides immense research interests in organic 2D nanotechnology for exploiting green technologies in the future.
基金supported by the Croucher Foundation(Croucher Innovation Award)the Research Grants Council(HKU17305914P,C7036-17W)
文摘We investigate two-photon transitions to the electron-hole scattering continuum in monolayer transition-metal dichalcogenides, and identify two contributions to this nonlinear optical process with opposite circularly polarized valley selection rules. In the non-interacting limit, the competition between the two contributions leads to a crossover of the selection rule with the increase of the two-photon energy. With the strong Coulomb interaction between the electron and hole, the two contributions excite electron-hole scattering states in orthogonal angular momentum channels, while the strength of the transition can be substantially enhanced by the interaction. Based on this picture of the two-photon transition, the second harmonic generation(SHG) in the electron-hole continuum is analyzed, where the Coulomb interaction is shown to greatly alter the relative strength of different cross-circular polarized SHG processes. Valley current injection by the quantum interference of one-photon and two-photon transition is also investigated in the presence of the strong Coulomb interaction, which significantly enhances the injection rate.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11374092,61474040,61574054,and 61505051)the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province,Chinathe Science and Technology Department of Hunan Province,China(Grant No.2014FJ2001)
文摘Atomically thin two-dimensional （2D） layered materials have potential applications in nanoelectronics, nanophoton- ics, and integrated optoelectronics. Band gap engineering of these 2D semiconductors is critical for their broad applications in high-performance integrated devices, such as broad-band photodetectors, multi-color light emitting diodes （LEDs）, and high-efficiency photovoltaic devices. In this review, we will summarize the recent progress on the controlled growth of composition modulated atomically thin 2D semiconductor alloys with band gaps tuned in a wide range, as well as their induced applications in broadly tunable optoelectronic components. The band gap engineered 2D semiconductors could open up an exciting opportunity for probing their fundamental physical properties in 2D systems and may find diverse applications in functional electronic/optoelectronic devices.
基金supported by the National Natural Science Foundation of China(Nos.52072035,51631001,21801015,51702016,51902023,51872030)Joint R&D Plan of Hongkong+3 种基金MacaoTaiwan and Beijing(No.Z191100001619002)the Fundamental Research Funds for the Central Universities(No.2017CX01003)the Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘Elemental doping confined in atomically-thin 2 D semiconductors offers a compelling strategy for constructing high performance photocatalysts.Although impressive progress has been achieved based on co-thermolysis method,the choices of dopants as well as semiconductor hosts are still quite limited to yield the elaborate photocatalyst with atomic-layer-confined doping defects,owing to the difficulty in balancing the reaction kinetics of different precursors.This study shows that the cation exchange reaction,which is dictated by the Pearson's hard and soft acids and bases(HSAB)theory and allowed to proceed at mild temperatures,can be developed into a conceptually new protocol for engineering elemental doping confined in semiconductor atomic layers.To this aim,the two atomic layers of a new type of 2 D photocatalyst PdSe0_(3)(PdSe0_(3)2 ALs,1.1 nm)are created by liquid exfoliation and exploited as a proof-of-concept prototype.It is demonstrated that the Mn(Ⅱ)dopants with controlled concentrations can be incorporated into PdSeO_(3)2 ALs via topological Mn^(2+) for-Pd^(2+) cation exchange performed in water/isopropanol solution at 30℃.The resulting Mn-doped PdSeO_(3)2 ALs present enhanced capacity for driving photocatalytic oxidation reactions in comparison with their undoped counterparts.The findings here suggest that the new route mediated by post synthetic cation exchange promises to give access to manifold 2 D confined-doping photocatalysts,with little perturbations on the thickness,morphology,and crystal structure of the atomically-thin semiconductor hosts.
基金supported by the Foundation for Polish Science through the IRA Programme financed by EU within SG OP Programmesupport by the Austrian Science Foundation-FWF (P31423 and P26830)the Austrian Exchange Service (OAD) Project PL-01/2017
文摘The interplay of magnetic and semiconducting properties has been in the focus for more than a half of the century. In this introductory article we briefly review the key properties and functionalities of various magnetic semiconductor families, including europium chalcogenides, chromium spinels, dilute magnetic semiconductors, dilute ferromagnetic semiconductors and insulators, mentioning also sources of non-uniformities in the magnetization distribution, accounting for an apparent high Curie temperature ferromagnetism in many systems. Our survey is carried out from today's perspective of ferromagnetic and antiferromagnetic spintronics as well as of the emerging fields of magnetic topological materials and atomically thin 2D layers.
基金financially supported by the National Natural Science Foundation of China(No.52171141)the Fund of Natural Science Special(Special Post)Research Foundation of Guizhou University(No.2023-032)the Fund of Research Foundation of Guizhou University(No.2024-33)
文摘Currently,the development of high-efficiency two-dimensional(2D)transistors is still hindered by the limited availability of suitable semiconductors and the contact resistance between the metal contact and the 2D semiconductors.Endeavors to address these challenges are highly desired.In this study,we conducted a comprehensive exploration of the potential 2D transition metal dinitrides(TMN_(2)s,TM=all the 3d,4d and 5d transition metals)with hexagonal(h-)and trigonal(t-)phases through systematic first-principles calculations.Among all h-TMN_(2)s and t-TMN_(2)s structures,we identified 8 TMN_(2)s that exhibit dynamical and thermal stability at room temperature.Of these,the h-TiN_(2),h-ZrN_(2)and h-HfN_(2)arefound to be semiconductors,and their direct bang gap,calculated at the HSE06 level,are 1.48,1.96 and 2.64 eV,respectively.The electron and hole mobility(μ_(e)andμ_(h))of these three structures exceed 1×10^(4)and1×10^(3)cm^(2)·V^(-1)·s^(-1),respectively.Especially,theμeof h-TiN_(2)amounts to 2.5×10^(4)cm^(2)·V^(-1)·s^(-1),and theμhof h-ZrN_(2)reaches to 7.7×10^(3)cm^(2)·V^(-1)·s^(-1).Importantly,unlike the MoS_(2)system,h-TMN_(2)forms Ohm contacts with both transition metals(e.g.,Cu)and 2D metals(e.g.,graphene),with tunneling possibilities exceeding 50%in the Cu system.These outstanding intrinsic semiconductor properties and contact characteristics exhibited by h-TMN_(2)highlight the immense potential of transition metal dinitrides in driving the advancement of next-generation information devices.Our findings significantly broaden the range of 2D materials and provide valuable insights for the development of high-eficiency 2D information devices.
基金partially supported by the Natural Science Foundation of Hubei Province(No.2022CFC030)the Science and Technology Research Project of Hubei Provincial Department of Education(No.D20212603)+2 种基金Hubei University of Arts and Science(No.2020kypytd002)the support from National Natural Science Foundation of China(No.22303098)the support from Anhui Provincial Natural Science Foundation(No.1908085MA10)。
文摘Intrinsic two-dimensional(2D)ferromagnetic(FM)semiconductors have attracted extensive attentions for their potential applications in next-generation spintronics devices.In recent years,the van der Waals material VI_(3) has been experimentally found to be an intrinsic FM semiconductor.However,the electronic structure of the VI_(3) is not fully understood.To reveal why the VI_(3)is a ferromagnetic semiconductor with strong out-of-plane anisotropy,we systematically studied the electronic structure of the monolayer VI_(3).Our results confirm that the monolayer VI_(3) is a Mott insulator,and d^(2) electrons occupy a_(g) and e_(g)^(π+) orbitals.The half-metallic state is a metastable state with a total energy 0.7 e V higher than the ferromagnetic Mott insulating state.Furthermore,our study confirmed that the VI_(3)exhibits the out-of-plane magnetic anisotropy,which originates from d^(2) electrons occupying low-lying agand egπ+orbitals.Since the orbital angular momentum of the e_(g)^(π+) state is not completely quenched,the VI_(3) has the out-of-plane anisotropy under interplay between the spin-orbit coupling and crystal field.Our study provides valuable guidance for the design of 2D magnetic materials with pronounced out-of-plane anisotropy.
基金the National Natural Science Foundation of China(Nos.21775018,21675022)the Natural Science Foundation of Jiangsu Province(No.BK20170084)+1 种基金the Open Funds of the State Key Laboratory of Electroanalytical Chemistry(No.SKLEAC201909)the Fundamental Research Funds for the Central Universities。
文摘As a class of metal-free two-dimensional(2D)semiconductor materials,polymeric carbon nitrides have attracted wide attention recently due to its facile regulation of the molecular and electronic structures,availability in abundance and high stability.According to the different ratios of C and N atoms in the fra mework,a series of C_(x)N_(y)materials have been successfully synthesized by virtue of various precursors,which further triggers extensive investigations of broad applications ranging from sustainable photocatalytic reactions and highly sensitive optoelectronic biosensing.In view of topological structures on their electronic structures and material properties,the as-reported C_(x)N_(y)could be generally classified into two main categories with three-or six-bond-extending frameworks.Owing to the effective n→π*transition in most C_(x)N_(y)materials,the relative energy level of the lone-pair electrons on N atoms is high,which thus endows the mate rials with the capability of visible light absorption.Meanwhile,the different repeating units,bridging groups and defect sites of these two kinds of C_(x)N_(y)allow them to effectively drive a diverse of promising applications that require specific electronic,inte rfacial and geometric properties.This review paper aims to summarize the recent progress in topological structure design and the relevant electronic band structures and striking properties of C_(x)N_(y)materials,In the final part,we also discuss the existing challenges of C_(x)N_(y)and outlook the prospect possibilities.
基金supports from the Electron Microscopy Center at the University of Chinese Academy of Sciencesfinancially supported by the Ministry of Science and Technology (MOST)of China (Grant No.2018YFE0202700)+3 种基金the Beijing Outstanding Young Scientist Program (Grant No.BJJWZYJH01201914430039)the China National Postdoctoral Program for Innovative Talents (Grant No.BX2021301)the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China (Grants No.22XNKJ30)。
文摘The design and preparation of novel quantum materials with atomic precision are crucial for exploring new physics and for device applications.Electron irradiation has been demonstrated as an effective method for preparing novel quantum materials and quantum structures that could be challenging to obtain otherwise.It features the advantages of precise control over the patterning of such new materials and their integration with other materials with different functionalities.Here,we present a new strategy for fabricating freestanding monolayer SiC within nanopores of a graphene membrane.By regulating the energy of the incident electron beam and the in-situ heating temperature in a scanning transmission electron microscope(STEM),we can effectively control the patterning of nanopores and subsequent growth of monolayer SiC within the graphene lattice.The resultant SiC monolayers seamlessly connect with the graphene lattice,forming a planar structure distinct by a wide direct bandgap.Our in-situ STEM observations further uncover that the growth of monolayer SiC within the graphene nanopore is driven by a combination of bond rotation and atom extrusion,providing new insights into the atom-by-atom self-assembly of freestanding two-dimensional(2D)monolayers.
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supported by the National Natural Science Foundation of China(No.22273084,No.22022305)the Open Fund of the State Key Labora-tory of Molecular Reaction Dynamics in DICP,CAS.
