Nonmetal elements strictly govern the electrochemical performance of molybdenum compounds.Yet,the exact role played by nonmetals during electrocatalysis remains largely obscure.With intermetallic MoSi_2comprising sili...Nonmetal elements strictly govern the electrochemical performance of molybdenum compounds.Yet,the exact role played by nonmetals during electrocatalysis remains largely obscure.With intermetallic MoSi_2comprising silicene subunits,we present an unprecedented hydrogen evolution reaction(HER)behavior in aqueous alkaline solution.Under continuous operation,the HER activity of MoSi_2shows a more than one order of magnitude improvement in current density from 1.1 to 21.5 mA cm^(à2)at 0.4 V overpotential.Meanwhile,this activation behavior is highly reversible,such that voltage withdrawal leads to catalyst inactivation but another operation causes reactivation.Thus,the system shows dynamics strikingly analogous to the legendary Sisyphus’labor,which drops and recovers in a stepwise manner repeatedly,but never succeeds in reaching the top of the mountain.Isomorphic WSi_2behaves almost the same as MoSi_2,whereas other metal silicides with silicyne subunits,including CrSi_2and TaSi_2,do not exhibit any anomalous behavior.A thin amorphous shell of MoSi_2is observed after reaction,within which the Si remains partially oxidized while the oxidation state of Mo is basically unchanged.First-principles calculations further reveal that the adsorption of hydroxide ions on silicene subunit edges and the subsequent Si vacancy formation in MoSi_2jointly lead to the anomalous HER kinetics of the adjacent Mo active centers.This work demonstrates that the role of nonmetal varies dramatically with the electronic and crystallographic structures of silicides and that silicene structural subunit may serve as a promoter for boosting HER in alkaline media.展开更多
Graphene,an emerging fabric of carbon atoms,has manifested its versatility in all kinds of fields encompassing electronics,optoelectronics,thermoelectrics,taking advantage of its excellent mechanical strength,exceptio...Graphene,an emerging fabric of carbon atoms,has manifested its versatility in all kinds of fields encompassing electronics,optoelectronics,thermoelectrics,taking advantage of its excellent mechanical strength,exceptional electronic and thermal conductivities,high surface specific area,and so forth.The prosperity of graphene never seen before has led the attention to silicene,siloxene,germanene,stanene,and plumbene due to their promising applications in the quantum spin Hall effect,topological insulator,batteries,capacitors,catalysis,and topological superconductivity.Herein,we review the existing production methods,numerous applications of two-dimensional group-IVA materials,and critically discuss the challenges of these materials,providing potential implications to the exploration of uncharted material systems.展开更多
Using the two-dimensional ionic Hubbard model as a simple basis for describing the electronic structure of silicene in the presence of an electric field induced by the substrate, we use the coherent-potential approxim...Using the two-dimensional ionic Hubbard model as a simple basis for describing the electronic structure of silicene in the presence of an electric field induced by the substrate, we use the coherent-potential approximation to calculate tbe zero-temperature phase diagram and the associated spectral function at half filling. We find that any degree of symmetry- breaking induced by the electric field causes the silicene structure to lose its Dirac fermion characteristics, thus providing a simple mechanism for the disappearance of the Dirac cone.展开更多
The structural and vibrational properties of two-dimensional hexagonal silicon （silicene） and germanium （germanene） are investigated by means of first-principles calculations. It is predicted that the silicene （g...The structural and vibrational properties of two-dimensional hexagonal silicon （silicene） and germanium （germanene） are investigated by means of first-principles calculations. It is predicted that the silicene （germanene） structure with a small buckling of 0.44 ,~ （0.7/k） and bond lengths of 2.28 ,~ （2.44 .~） is energetically the most favorable, and it does not exhibit imaginary phonon mode. The calculated non-resonance Raman spectra of silicene are characterized by a main peak at about 575 cm-1, namely the G-like peak. For germanene, the highest peak is at about 290 cm-1. Extensive calculations on armchair silicene nanoribbons and armchair germanene nanoribbons are also performed, with and without hydrogenation of the edges. The studies reveal other Raman peaks mainly distributed at lower frequencies than the G-like peak which could be attributed to the defects at the edges of the ribbons, thus not present in the Raman spectra of non-defective silicene and germanene. Particularly the Raman peak corresponding to the D mode is found to be located at around 515 cm-1 for silicene and 270 cm-1 for germanene. The calculated G-like and the D peaks are likely the fingerprints of the Raman spectra of the low-buckled structures of silicene and germanene.展开更多
基于含时密度泛函理论,研究了硅烯量子点的等离激元激发.沿量子点所在的平面方向,体系中有两个主要的等离激元共振带.一个等离激元共振带位于2.0 e V附近,另一个等离激元共振带位于7.0 e V附近.由于离域化的π电子参与了两个等离激元共...基于含时密度泛函理论,研究了硅烯量子点的等离激元激发.沿量子点所在的平面方向,体系中有两个主要的等离激元共振带.一个等离激元共振带位于2.0 e V附近,另一个等离激元共振带位于7.0 e V附近.由于离域化的π电子参与了两个等离激元共振带的激发,沿激发方向随着矩形硅烯量子点边长的增加,体系的两个等离激元共振带都发生红移.硅烯量子点的等离激元激发还依赖于边界的构型.此外,由于六角形硅烯量子点的对称性较高,沿量子点所在平面的不同方向激发时,体系的等离激元共振模式相同.展开更多
Van der Waals stacking of two-dimensional crystals with rotation or mismatch in lattice constants gives rise to rich physical phenomena that are closely related to the strong correlations and band topology.Twisted gra...Van der Waals stacking of two-dimensional crystals with rotation or mismatch in lattice constants gives rise to rich physical phenomena that are closely related to the strong correlations and band topology.Twisted graphene and silicene heterobilayers have been theoretically predicted to host a tunable transport gap due to the mismatch of Dirac cones in the graphene and silicene layers.However,experimental realization of such twisted structure is challenging.Here,we report the formation of twisted graphene/silicene bilayers on Ru(0001)crystal via intercalation.Different moirépatterns form as single-crystalline graphene grows over different grains of the Ru surface.After silicon intercalation,graphene/silicene bilayers are observed with different twisting angles on top of different grains of the Ru substrate.Our work provides a new pathway towards construction of graphene based twisted heterobilayers.展开更多
Rechargeable ion batteries require anode materials with excellent performance,presenting a key challenge for researchers.This paper explores the potential of using two-dimensional dumbbell silicene as an anode materia...Rechargeable ion batteries require anode materials with excellent performance,presenting a key challenge for researchers.This paper explores the potential of using two-dimensional dumbbell silicene as an anode material for alkali metal ion batteries through density functional theory(DFT)calculations.Our findings demonstrate that alkali metal ions have negative adsorption energies on dumbbell silicene,and the energy barriers for Li/Na/K ion diffusion are as low as0.032 e V/0.055 e V/0.21 e V,indicating that metal ions can easily diffuse across the entire surface of dumbbell silicene.Additionally,the average open circuit voltages of dumbbell silicene as anode for Li-ion,Na-ion,and K-ion batteries are 0.42 V,0.41 V,and 0.60 V,respectively,with corresponding storage capacities of 716 m Ah/g,622 m Ah/g,and 716 m Ah/g.These results suggest that dumbbell silicene is an ideal anode material for Li-ion,Na-ion,and K-ion batteries,with high capacity,low open circuit voltage,and high ion diffusion kinetics.Moreover,our calculations show that the theoretical capacities obtained using DFT-D2 are higher than those obtained using DFT-D3,providing a valuable reference for subsequent theoretical calculations.展开更多
A first principles study on the stability and structural and electronic properties of two-dimensional silicon allotropes on a semiconducfing layered metal-chalcogenide compound, namely SnS2, is performed. The interact...A first principles study on the stability and structural and electronic properties of two-dimensional silicon allotropes on a semiconducfing layered metal-chalcogenide compound, namely SnS2, is performed. The interactions between the two- dimensional silicon layer, commonly known as silicene, and the layered SnS2 template are investigated by analyzing different configurations of silicene. The calculated thermodynamic phase diagram suggests that the most stable configuration of silicene on SnS2 belongs to a family of structures with Si atoms placed on three different planes; so-called dumbbell silicene. This particular dumbbell silicene structure preserves its atomic configuration on SnS2 even at a temperature of 500 K or as a ＂flake＂ layer （i.e., a silicene cluster terminated by H atoms）, thanks to the weak interactions between the silicene and the SnS2 layers. Remarkably, an electric field can be used to tune the band gap of the silicene layer on SnS2, eventually changing its electronic behavior from semiconducting to （semi）metallic. The stability of silicene on SnS2 is very promising for the integration of silicene onto semiconducting or insulating substrates. The tunable electronic behavior of the silicene/SnS2 van der Walls heterostructure is very important not only for its use in future nanoelectronic devices, but also as a successful approach to engineering the bang-gap of layered SnS2 paving the way for the use of this layered compound in energy harvesting applications.展开更多
The electrical characteristics of a double-gate armchair silicene nanoribbon field-effect-transistor （DG ASiNR FET） are thoroughly investigated by using a ballistic quantum transport model based on non-equilibrium G...The electrical characteristics of a double-gate armchair silicene nanoribbon field-effect-transistor （DG ASiNR FET） are thoroughly investigated by using a ballistic quantum transport model based on non-equilibrium Green＇s function （NEGF） approach self-consistently coupled with a three-dimensional （3D） Poisson equation. We evaluate the influence of variation in uniaxial tensile strain, ribbon temperature and oxide thickness on the on-off current ratio, subthreshold swing, transconductance and the delay time of a 12-nm-length ultranarrow ASiNR FET. A novel two-parameter strain mag- nitude and temperature-dependent model is presented for designing an optimized device possessing balanced amelioration of all the electrical parameters. We demonstrate that employing HfO2 as the gate insulator can be a favorable choice and simultaneous use of it with proper combination of temperature and strain magnitude can achieve better device performance. Furthermore, a general model power （GMP） is derived which explicitly provides the electron effective mass as a function of the bandgap of a hydrogen passivated ASiNR under strain.展开更多
We report the growth of Si nanostructures, either as thin films or nanoparticles, on graphene substrates. The Si nanostructures are shown to be single crystalline, air stable and oxidation resistive, as indicated by t...We report the growth of Si nanostructures, either as thin films or nanoparticles, on graphene substrates. The Si nanostructures are shown to be single crystalline, air stable and oxidation resistive, as indicated by the observation of a single crystalline Si Raman mode at around 520 cm^-1, a STM image of an ordered surface structure under ambient condition, and a Schottky junction with graphite. Ultra-thin silicon regions exhibit silicene-like behavior, including a Raman mode at around 550 cm^-1, a triangular lattice structure in STM that has distinctly different lattice spacing from that of either graphene or thicker Si, and metallic conductivity of up to 500 times higher than that of graphite. This work suggests a bottom-up approach to forming a Si nanostructure array on a large-scale patterned graphene substrate that can be used to fabricate nanoscale Si electronic devices.展开更多
√√The electronic structures of monolayer silicenes(4 × 4 and■ ×■R13.9o) grown on Ag(111) surface are studied by scanning tunneling spectroscopy(STS) and density functional theory(DFT) calculations. While...√√The electronic structures of monolayer silicenes(4 × 4 and■ ×■R13.9o) grown on Ag(111) surface are studied by scanning tunneling spectroscopy(STS) and density functional theory(DFT) calculations. While both phases have similar electronic structures around the Fermi level, significant differences are observed in the higher energy unoccupied states.The DFT calculations show that the contributions of Si 3pz orbitals to the unoccupied states are different because of their different buckled configurations.展开更多
Silicene, a two-dimensional(2D) honeycomb structure similar to graphene, has been successfully fabricated on various substrates. This work will mainly review the syntheses and the corresponding prope√rties o√f silic...Silicene, a two-dimensional(2D) honeycomb structure similar to graphene, has been successfully fabricated on various substrates. This work will mainly review the syntheses and the corresponding prope√rties o√f silicene and√ silice√ne–graphene layered structures on Ir(111) substrates. For silicene on Ir(111), the buckled(3 ×3) silicene/(7 ×7)Ir(111) configuration and its electronic structure are fully discussed. For silicene–graphene layered structures, silicene layer can be constructed underneath graphene layer by an intercalation method. These results indicate the possibility of integrating silicene with graphene and may link up with potential applications in nanoelectronics and related areas.展开更多
Silicene, a monolayer of silicon atoms arranged in a honeycomb lattice, has been undergoing rapid development in recent years due to its superior electronic properties and its compatibility with mature silicon-based s...Silicene, a monolayer of silicon atoms arranged in a honeycomb lattice, has been undergoing rapid development in recent years due to its superior electronic properties and its compatibility with mature silicon-based semiconductor technology. The successful synthesis of silicene on several substrates provides a solid foundation for the use of silicene in future microelectronic devices. In this review, we discuss the growth mechanism of silicene on an Ag(111) surface, which is crucial for achieving high quality silicene. Several critical issues related to the electronic properties of silicene are also summarized, including the point defect effect, substrate effect, intercalation of alkali metal, and alloying with transition metals.展开更多
Two-dimensional （2D） metamaterials are considered to be of enormous relevance to the progress of all exact sciences. Since the discovery of graphene, researchers have increasingly investigated in depth the details o...Two-dimensional （2D） metamaterials are considered to be of enormous relevance to the progress of all exact sciences. Since the discovery of graphene, researchers have increasingly investigated in depth the details of electrical/optical proper- ties pertinent to other 2D metamaterials, including those relating to the silicene. In this review are included the details and comparisons of the atomic structures, energy diagram bands, substrates, charge densities, charge mobilities, conductivities, absorptions, electrical permittivities, dispersion relations of the wave vectors, and supported electromagnetic modes related to graphene and silicene. Hence, this review can help readers to acquire, recover or increase the necessary technological basis for the development of more specific studies on graphene and silicene.展开更多
基金supported by the National Key Research and Development Program of China (2016YFA0202603)the National Basic Research Program of China (2013CB934103)+3 种基金the Programme of Introducing Talents of Discipline to Universities (B17034)the National Natural Science Foundation of China (51521001, 51832004)the National Natural Science Fund for Distinguished Young Scholars (51425204)the Fundamental Research Funds for the Central Universities (WUT: 2017III008, 2017III009)
文摘Nonmetal elements strictly govern the electrochemical performance of molybdenum compounds.Yet,the exact role played by nonmetals during electrocatalysis remains largely obscure.With intermetallic MoSi_2comprising silicene subunits,we present an unprecedented hydrogen evolution reaction(HER)behavior in aqueous alkaline solution.Under continuous operation,the HER activity of MoSi_2shows a more than one order of magnitude improvement in current density from 1.1 to 21.5 mA cm^(à2)at 0.4 V overpotential.Meanwhile,this activation behavior is highly reversible,such that voltage withdrawal leads to catalyst inactivation but another operation causes reactivation.Thus,the system shows dynamics strikingly analogous to the legendary Sisyphus’labor,which drops and recovers in a stepwise manner repeatedly,but never succeeds in reaching the top of the mountain.Isomorphic WSi_2behaves almost the same as MoSi_2,whereas other metal silicides with silicyne subunits,including CrSi_2and TaSi_2,do not exhibit any anomalous behavior.A thin amorphous shell of MoSi_2is observed after reaction,within which the Si remains partially oxidized while the oxidation state of Mo is basically unchanged.First-principles calculations further reveal that the adsorption of hydroxide ions on silicene subunit edges and the subsequent Si vacancy formation in MoSi_2jointly lead to the anomalous HER kinetics of the adjacent Mo active centers.This work demonstrates that the role of nonmetal varies dramatically with the electronic and crystallographic structures of silicides and that silicene structural subunit may serve as a promoter for boosting HER in alkaline media.
基金This study was supported by the National Key R&D Program of China(2017YFB1104300 and 2016YFA0200200)Natural Science Foundation of China(NSFC)(No.21671020,51433005 and 51673026)+1 种基金NSFC-MAECI(51861135202),Beijing Natural Science Foundation(2172049)Analysis&Testing Center,Beijing Institute of Technology.
文摘Graphene,an emerging fabric of carbon atoms,has manifested its versatility in all kinds of fields encompassing electronics,optoelectronics,thermoelectrics,taking advantage of its excellent mechanical strength,exceptional electronic and thermal conductivities,high surface specific area,and so forth.The prosperity of graphene never seen before has led the attention to silicene,siloxene,germanene,stanene,and plumbene due to their promising applications in the quantum spin Hall effect,topological insulator,batteries,capacitors,catalysis,and topological superconductivity.Herein,we review the existing production methods,numerous applications of two-dimensional group-IVA materials,and critically discuss the challenges of these materials,providing potential implications to the exploration of uncharted material systems.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11174219)the Program for New Century Excellent Talents in Universities,China (Grant No. NCET-13-0428)+2 种基金the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20110072110044)the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, Chinathe Scientific Research Foundation for the Returned Overseas Chinese Scholars of the Education Ministry of China
文摘Using the two-dimensional ionic Hubbard model as a simple basis for describing the electronic structure of silicene in the presence of an electric field induced by the substrate, we use the coherent-potential approximation to calculate tbe zero-temperature phase diagram and the associated spectral function at half filling. We find that any degree of symmetry- breaking induced by the electric field causes the silicene structure to lose its Dirac fermion characteristics, thus providing a simple mechanism for the disappearance of the Dirac cone.
文摘The structural and vibrational properties of two-dimensional hexagonal silicon （silicene） and germanium （germanene） are investigated by means of first-principles calculations. It is predicted that the silicene （germanene） structure with a small buckling of 0.44 ,~ （0.7/k） and bond lengths of 2.28 ,~ （2.44 .~） is energetically the most favorable, and it does not exhibit imaginary phonon mode. The calculated non-resonance Raman spectra of silicene are characterized by a main peak at about 575 cm-1, namely the G-like peak. For germanene, the highest peak is at about 290 cm-1. Extensive calculations on armchair silicene nanoribbons and armchair germanene nanoribbons are also performed, with and without hydrogenation of the edges. The studies reveal other Raman peaks mainly distributed at lower frequencies than the G-like peak which could be attributed to the defects at the edges of the ribbons, thus not present in the Raman spectra of non-defective silicene and germanene. Particularly the Raman peak corresponding to the D mode is found to be located at around 515 cm-1 for silicene and 270 cm-1 for germanene. The calculated G-like and the D peaks are likely the fingerprints of the Raman spectra of the low-buckled structures of silicene and germanene.
文摘基于含时密度泛函理论,研究了硅烯量子点的等离激元激发.沿量子点所在的平面方向,体系中有两个主要的等离激元共振带.一个等离激元共振带位于2.0 e V附近,另一个等离激元共振带位于7.0 e V附近.由于离域化的π电子参与了两个等离激元共振带的激发,沿激发方向随着矩形硅烯量子点边长的增加,体系的两个等离激元共振带都发生红移.硅烯量子点的等离激元激发还依赖于边界的构型.此外,由于六角形硅烯量子点的对称性较高,沿量子点所在平面的不同方向激发时,体系的等离激元共振模式相同.
基金the Ministry of Science and Technology of China(Nos.2019YFA0308500 and 2018YFA0305800)the National Natural Science Foundation of China(Nos.61888102,51991340,and 52072401)the Chinese Academy of Sciences Project for Young Scientists in Basic Research(No.YSBR-003).
文摘Van der Waals stacking of two-dimensional crystals with rotation or mismatch in lattice constants gives rise to rich physical phenomena that are closely related to the strong correlations and band topology.Twisted graphene and silicene heterobilayers have been theoretically predicted to host a tunable transport gap due to the mismatch of Dirac cones in the graphene and silicene layers.However,experimental realization of such twisted structure is challenging.Here,we report the formation of twisted graphene/silicene bilayers on Ru(0001)crystal via intercalation.Different moirépatterns form as single-crystalline graphene grows over different grains of the Ru surface.After silicon intercalation,graphene/silicene bilayers are observed with different twisting angles on top of different grains of the Ru substrate.Our work provides a new pathway towards construction of graphene based twisted heterobilayers.
基金the National Natural Science Foundation of China(Grant No.12274112)the Overseas Scientists Sponsorship Program of Hebei Province of China(Grant No.C20210330)the State Key Laboratory of Reliability and Intelligence of Electrical Equipment of Hebei University of Technology(Grant No.EERI PI2020009)。
文摘Rechargeable ion batteries require anode materials with excellent performance,presenting a key challenge for researchers.This paper explores the potential of using two-dimensional dumbbell silicene as an anode material for alkali metal ion batteries through density functional theory(DFT)calculations.Our findings demonstrate that alkali metal ions have negative adsorption energies on dumbbell silicene,and the energy barriers for Li/Na/K ion diffusion are as low as0.032 e V/0.055 e V/0.21 e V,indicating that metal ions can easily diffuse across the entire surface of dumbbell silicene.Additionally,the average open circuit voltages of dumbbell silicene as anode for Li-ion,Na-ion,and K-ion batteries are 0.42 V,0.41 V,and 0.60 V,respectively,with corresponding storage capacities of 716 m Ah/g,622 m Ah/g,and 716 m Ah/g.These results suggest that dumbbell silicene is an ideal anode material for Li-ion,Na-ion,and K-ion batteries,with high capacity,low open circuit voltage,and high ion diffusion kinetics.Moreover,our calculations show that the theoretical capacities obtained using DFT-D2 are higher than those obtained using DFT-D3,providing a valuable reference for subsequent theoretical calculations.
文摘A first principles study on the stability and structural and electronic properties of two-dimensional silicon allotropes on a semiconducfing layered metal-chalcogenide compound, namely SnS2, is performed. The interactions between the two- dimensional silicon layer, commonly known as silicene, and the layered SnS2 template are investigated by analyzing different configurations of silicene. The calculated thermodynamic phase diagram suggests that the most stable configuration of silicene on SnS2 belongs to a family of structures with Si atoms placed on three different planes; so-called dumbbell silicene. This particular dumbbell silicene structure preserves its atomic configuration on SnS2 even at a temperature of 500 K or as a ＂flake＂ layer （i.e., a silicene cluster terminated by H atoms）, thanks to the weak interactions between the silicene and the SnS2 layers. Remarkably, an electric field can be used to tune the band gap of the silicene layer on SnS2, eventually changing its electronic behavior from semiconducting to （semi）metallic. The stability of silicene on SnS2 is very promising for the integration of silicene onto semiconducting or insulating substrates. The tunable electronic behavior of the silicene/SnS2 van der Walls heterostructure is very important not only for its use in future nanoelectronic devices, but also as a successful approach to engineering the bang-gap of layered SnS2 paving the way for the use of this layered compound in energy harvesting applications.
文摘The electrical characteristics of a double-gate armchair silicene nanoribbon field-effect-transistor （DG ASiNR FET） are thoroughly investigated by using a ballistic quantum transport model based on non-equilibrium Green＇s function （NEGF） approach self-consistently coupled with a three-dimensional （3D） Poisson equation. We evaluate the influence of variation in uniaxial tensile strain, ribbon temperature and oxide thickness on the on-off current ratio, subthreshold swing, transconductance and the delay time of a 12-nm-length ultranarrow ASiNR FET. A novel two-parameter strain mag- nitude and temperature-dependent model is presented for designing an optimized device possessing balanced amelioration of all the electrical parameters. We demonstrate that employing HfO2 as the gate insulator can be a favorable choice and simultaneous use of it with proper combination of temperature and strain magnitude can achieve better device performance. Furthermore, a general model power （GMP） is derived which explicitly provides the electron effective mass as a function of the bandgap of a hydrogen passivated ASiNR under strain.
基金supported by ARO/Materials Science(Grant No.W911NF-10-1-0281 and W911NF-18-1-0079,managed by Dr.Chakrapani Varanasi)
文摘We report the growth of Si nanostructures, either as thin films or nanoparticles, on graphene substrates. The Si nanostructures are shown to be single crystalline, air stable and oxidation resistive, as indicated by the observation of a single crystalline Si Raman mode at around 520 cm^-1, a STM image of an ordered surface structure under ambient condition, and a Schottky junction with graphite. Ultra-thin silicon regions exhibit silicene-like behavior, including a Raman mode at around 550 cm^-1, a triangular lattice structure in STM that has distinctly different lattice spacing from that of either graphene or thicker Si, and metallic conductivity of up to 500 times higher than that of graphite. This work suggests a bottom-up approach to forming a Si nanostructure array on a large-scale patterned graphene substrate that can be used to fabricate nanoscale Si electronic devices.
基金supported by the Ministry of Education,Culture,Sports,Science and Technology(MEXT) through Grants-in-Aid for Scientific Research(Grant Nos.24241040 and 25110008)the World Premier International Research Center Initiative(WPI),MEXT,Japan
文摘√√The electronic structures of monolayer silicenes(4 × 4 and■ ×■R13.9o) grown on Ag(111) surface are studied by scanning tunneling spectroscopy(STS) and density functional theory(DFT) calculations. While both phases have similar electronic structures around the Fermi level, significant differences are observed in the higher energy unoccupied states.The DFT calculations show that the contributions of Si 3pz orbitals to the unoccupied states are different because of their different buckled configurations.
基金supported by the National Basic Research Program of China(Grant Nos.2013CBA01600 and 2011CB932700)the National Natural Science Foundation of China(Grant Nos.61222112,61390501,51325204,11334006,and 61306114)+1 种基金the Science Fund from Chinese Academy of Sciences(Grant Nos.1731300500015 and XDB07030100)the Fundamental Research Funds for the Central Universities,China
文摘Silicene, a two-dimensional(2D) honeycomb structure similar to graphene, has been successfully fabricated on various substrates. This work will mainly review the syntheses and the corresponding prope√rties o√f silicene and√ silice√ne–graphene layered structures on Ir(111) substrates. For silicene on Ir(111), the buckled(3 ×3) silicene/(7 ×7)Ir(111) configuration and its electronic structure are fully discussed. For silicene–graphene layered structures, silicene layer can be constructed underneath graphene layer by an intercalation method. These results indicate the possibility of integrating silicene with graphene and may link up with potential applications in nanoelectronics and related areas.
基金supported by the National Natural Science Foundation of China(Grant No.11134005)
文摘Silicene, a monolayer of silicon atoms arranged in a honeycomb lattice, has been undergoing rapid development in recent years due to its superior electronic properties and its compatibility with mature silicon-based semiconductor technology. The successful synthesis of silicene on several substrates provides a solid foundation for the use of silicene in future microelectronic devices. In this review, we discuss the growth mechanism of silicene on an Ag(111) surface, which is crucial for achieving high quality silicene. Several critical issues related to the electronic properties of silicene are also summarized, including the point defect effect, substrate effect, intercalation of alkali metal, and alloying with transition metals.
基金Project supported by the National Council for Scientific and Technological Development(CNPq)
文摘Two-dimensional （2D） metamaterials are considered to be of enormous relevance to the progress of all exact sciences. Since the discovery of graphene, researchers have increasingly investigated in depth the details of electrical/optical proper- ties pertinent to other 2D metamaterials, including those relating to the silicene. In this review are included the details and comparisons of the atomic structures, energy diagram bands, substrates, charge densities, charge mobilities, conductivities, absorptions, electrical permittivities, dispersion relations of the wave vectors, and supported electromagnetic modes related to graphene and silicene. Hence, this review can help readers to acquire, recover or increase the necessary technological basis for the development of more specific studies on graphene and silicene.
