分别采用超声微波溶剂热法、常压溶剂热法及高压溶剂热法制备In_2Se_3/CuSe粉体,研究不同方法制备In_2Se_3/CuSe粉体的物相、形貌,并利用涂覆–快速热处理法制作薄膜太阳电池吸收层。通过XRD、Raman、FESEM和TEM对样品的物相、形貌和组...分别采用超声微波溶剂热法、常压溶剂热法及高压溶剂热法制备In_2Se_3/CuSe粉体,研究不同方法制备In_2Se_3/CuSe粉体的物相、形貌,并利用涂覆–快速热处理法制作薄膜太阳电池吸收层。通过XRD、Raman、FESEM和TEM对样品的物相、形貌和组成进行了表征。结果表明:超声微波溶剂热法和常压溶剂热法得到的产物是以In_2Se_3+CuSe混合相的形式存在,高压溶剂热法合成的In_2Se_3/CuSe粉体则呈核壳结构,(以In_2Se_3为核,CuSe为壳)。涂覆–快速热处理法制备CIS薄膜的FESEM照片结果表明,高压溶剂热法合成的In_2Se_3/CuSe更容易获得平整致密的薄膜。将该CIS薄膜直接用于电池器件的组装,获得的光电性能参数:Voc为50 m V,Jsc为8 m A/cm^2。展开更多
Epitaxial growth and structural characteristics of metastableβ-In2Se3 thin films on H-terminated Si(111)substrates are studied.The In2Se3 thin films grown below theβ-to-αphase transition temperature(453 K)are chara...Epitaxial growth and structural characteristics of metastableβ-In2Se3 thin films on H-terminated Si(111)substrates are studied.The In2Se3 thin films grown below theβ-to-αphase transition temperature(453 K)are characterized to be strainedβ-In2Se3 mixed with significantγ-In2Se3 phases.The pure-phased single-crystallineβ-In2Se3 can be reproducibly achieved by in situ annealing the as-deposited poly-crystalline In2Se3 within the phase equilibrium temperature window ofβ-In2Se3.It is suggeted that the observedγ-to-βphase transition triggered by quite a low annealing temperature should be a rather lowered phase transition barrier of the epitaxy-stabilized In2Se3 thin-film system at a state far from thermodynamic equilibrium.展开更多
The layer-dependent properties are still unclarified in two-dimensional(2D)vertical heterostructures.In this study,we layer-bylayer deposited semimetalβ-In2Se3 on monolayer MoS2 to form verticalβ-In2Se3/MoS2 heteros...The layer-dependent properties are still unclarified in two-dimensional(2D)vertical heterostructures.In this study,we layer-bylayer deposited semimetalβ-In2Se3 on monolayer MoS2 to form verticalβ-In2Se3/MoS2 heterostructures by chemical vapor deposition.The defect-mediated nucleation mechanism inducesβ-In2Se3 nanosheets to grow on monolayer MoS2,and the layer number of stackedβ-In2Se3 can be precisely regulated from 1 layer(L)to 13 L by prolonging the growth time.Theβ-In2Se3/MoS2 heterostructures reveal tunable type-Ⅱband alignment arrangement by altering the layer number ofβ-In2Se3,which optimizes the internal electron transfer.Meanwhile,the edge atomic structure ofβ-In2Se3 stacking on monolayer MoS2 shows the reconstruction derived from large lattice mismatch(~29%),and the presence ofβ-In2Se3 also further increases the electrical conductivity ofβ-In2Se3/MoS2 heterostructures.Attributed to abundant layer-dependent edge active sites,edge reconstruction,improved hydrophilicity,and high electrical conductivity ofβ-In2Se3/MoS2 heterostructures,the edge ofβ-In2Se3/MoS2 heterostructures exhibits excellent electrocatalytic hydrogen evolution performance.Lower onset potential and smaller Tafel slope can be observed at the edge of monolayer MoS2 coupled with 13-Lβ-In2Se3.Hence,the outstanding conductive layers coupled with edge reconstruction in 2D vertical heterostructures play decisive roles in the optimization of electron energy levels and improvement of layer-dependent catalytic performance.展开更多
Thermal transport in superlattices is governed by various phonon-scattering processes. For extracting the phonon-scattering contribution of hetero-interfaces in chalcogenide superlattices, single-crystalline Bi2Se3/In...Thermal transport in superlattices is governed by various phonon-scattering processes. For extracting the phonon-scattering contribution of hetero-interfaces in chalcogenide superlattices, single-crystalline Bi2Se3/In2Se3 （BS/IS） superlattices with minimized defects are prepared on fluorophlogopite mica by molecular beam epitaxy. The cross-plane heat-conducting properties of the BS/IS superlattices are demonstrated to depend precisely on the period thicknesses and constituents of the superlattices, where a minimum in the thermal conductivity indicates a crossover from particle-like to wave-like phonon transport in the superlattices. The thermal-conductivity minimum of the BS/IS superlattices is nearly one order of magnitude lower than that of intrinsic BS film.展开更多
Multiferroic materials exhibit tremendous potentials in novel magnetoelectric devices such as high-density non-volatile storage.Herein,we report the coexistence of ferroelectricity and ferromagnetism in two-dimensiona...Multiferroic materials exhibit tremendous potentials in novel magnetoelectric devices such as high-density non-volatile storage.Herein,we report the coexistence of ferroelectricity and ferromagnetism in two-dimensional Fedoped In2Se3(Fe0.16In1.84Se3,FIS).The Fe atoms were doped at the In atom sites and the Fe content is^3.22%according to the experiments.Our first-principles calculation based on the density-functional theory predicts a magnetic moment of 5μB per Fe atom when Fe substitutes In sites in In2Se3.The theoretical prediction was further confirmed experimentally by magnetic measurement.The results indicate that pure In2Se3 is diamagnetic,whereas FIS exhibits ferromagnetic behavior with a parallel anisotropy at 2 K and a Curie temperature of^8 K.Furthermore,the sample maintains stable room-temperature ferroelectricity in piezoresponse force microscopy(PFM)measurement after the introduction of Fe atom into the ferroelectric In2Se3 nanoflakes.The findings indicate that the layered Fe0.16In1.84Se3 materials have potential in future nanoelectronic,magnetic,and optoelectronic applications.展开更多
Ferroelectric memory is a promising candidate for next-generation nonvolatile memory owing to its outstanding performance such as low power consump-tion,fast speed,and high endurance.However,the ferroelectricity of co...Ferroelectric memory is a promising candidate for next-generation nonvolatile memory owing to its outstanding performance such as low power consump-tion,fast speed,and high endurance.However,the ferroelectricity of conven-tional ferroelectric materials will be eliminated by the depolarization field when the size drops to the nanometer scale.As a result,the miniaturization of ferroelectric devices was hindered,which makes ferroelectric memory unable to keep up with the development of integrated-circuit(IC)miniaturization.Recently,a two-dimensional(2D)In2Se3 was reported to maintain stable ferro-electricity at the ultrathin scale,which is expected to break through the bottle-neck of miniaturization.Soon,devices based on 2D In2Se3,including the ferroelectric field-effect transistor,ferroelectric channel transistor,synaptic fer-roelectric semiconductor junction,and ferroelectric memristor were demon-strated.However,a comprehensive understanding of the structures and the ferroelectric-switching mechanism of 2D In2Se3 is still lacking.Here,the atomic structures of different phases,the dynamic mechanism of ferroelectric switching,and the performance/functions of the latest devices of 2D In2Se3 are reviewed.Furthermore,the correlations among the structures,the properties,and the device performance are analyzed.Finally,several crucial problems or challenges and possible research directions are put forward.We hope that this review paper can provide timely knowledge and help for the research commu-nity to develop 2D In2Se3 based ferroelectric memory and computing technol-ogy for practical industrial applications.展开更多
The electric control of magnetic properties based on magnetoelectric effect is crucial for the development of future data storage devices.Here,based on first-principles calculations,a strong magnetoelectric effect is ...The electric control of magnetic properties based on magnetoelectric effect is crucial for the development of future data storage devices.Here,based on first-principles calculations,a strong magnetoelectric effect is proposed to effectively switch on/off the magnetic states as well as alter the in-plane/perpendicular easy axes of metal-phthalocyanine molecules(MPc)by reversing the electric polarization of the underlying two-dimensional(2D)ferroelectric a-In2Se3 substrate with the application of an external electric field.The mechanism originates from the different hybridization between the molecule and the ferroelectric substrate in which the different electronic states of surface Se layer play a dominant role.Moreover,the magnetic moments and magnetic anisotropy energies(MAE)of OsPc/In2Se3 can be further largely enhanced by a functionalized atom atop the OsPc molecule.The I-OsPc/In2Se3 system possesses large MAE up to 30 meV at both polarization directions,which is sufficient for room-temperature applications.These findings provide a feasible scheme to realize ferroelectric control of magnetic states in 2D limit,which have great potential for applications in nanoscale electronics and spintronics.展开更多
With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Gao Chunxiao(高春晓)from the State Key Laboratory for Superhard Materials,Institute of Atom...With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Gao Chunxiao(高春晓)from the State Key Laboratory for Superhard Materials,Institute of Atomic and Molecular Physics,Jilin University and Prof.Chen Bin from the展开更多
Favourable band alignment and excellent visible light response are vital for photochemical water splitting.In this work,we have theoretically investigated how ferroelectric polarization and its reversibility in direct...Favourable band alignment and excellent visible light response are vital for photochemical water splitting.In this work,we have theoretically investigated how ferroelectric polarization and its reversibility in direction can be utilized to modulate the band alignment and optical absorption properties.For this objective,2D van der Waals heterostructures(HTSs)are constructed by interfacing monolayer M0 S2 with ferroelectric In2 Se3.We find the switch of polarization direction has dramatically changed the band alignment,thus facilitating different type of reactions.In Iri2 Se3/MoS2/In2 Se3 heterostructures,one polarization direction supports hydrogen evolution reaction and another polarization direction can favour oxygen evolution reaction.These can be used to create tuneable photocatalyst materials where water reduction reactions can be selectively controlled by polarization switching.The modulation of band alignment is attributed to the shift of reaction potential caused by spontaneous polarization.Additionally,the formed type-II van der Waals HTSs also significantly improve charge separation and enhance the optical absorption in the visible and infrared regions.Our results pave a way in the design of van der Waals HTSs for water splitting using ferroelectric materials.展开更多
文摘分别采用超声微波溶剂热法、常压溶剂热法及高压溶剂热法制备In_2Se_3/CuSe粉体,研究不同方法制备In_2Se_3/CuSe粉体的物相、形貌,并利用涂覆–快速热处理法制作薄膜太阳电池吸收层。通过XRD、Raman、FESEM和TEM对样品的物相、形貌和组成进行了表征。结果表明:超声微波溶剂热法和常压溶剂热法得到的产物是以In_2Se_3+CuSe混合相的形式存在,高压溶剂热法合成的In_2Se_3/CuSe粉体则呈核壳结构,(以In_2Se_3为核,CuSe为壳)。涂覆–快速热处理法制备CIS薄膜的FESEM照片结果表明,高压溶剂热法合成的In_2Se_3/CuSe更容易获得平整致密的薄膜。将该CIS薄膜直接用于电池器件的组装,获得的光电性能参数:Voc为50 m V,Jsc为8 m A/cm^2。
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0306102 and 2018YFA0306703)the National Natural Science Foundation of China(Grant Nos.61474014 and U1601208)the Sichuan Science and Technology Program,China(Grant Nos.2019YJ0202 and 20GJHZ0229).
文摘Epitaxial growth and structural characteristics of metastableβ-In2Se3 thin films on H-terminated Si(111)substrates are studied.The In2Se3 thin films grown below theβ-to-αphase transition temperature(453 K)are characterized to be strainedβ-In2Se3 mixed with significantγ-In2Se3 phases.The pure-phased single-crystallineβ-In2Se3 can be reproducibly achieved by in situ annealing the as-deposited poly-crystalline In2Se3 within the phase equilibrium temperature window ofβ-In2Se3.It is suggeted that the observedγ-to-βphase transition triggered by quite a low annealing temperature should be a rather lowered phase transition barrier of the epitaxy-stabilized In2Se3 thin-film system at a state far from thermodynamic equilibrium.
基金The work was supported by the National Natural Science Foundation of China(Nos.22175060 and 21975067)Natural Science Foundation of Hunan Province of China(Nos.2021JJ10014 and 2021JJ30092)+1 种基金X.X.X thanks to the National Science Foundation of China(No.12104385)The computational resources were provided by the supercomputer TianHe in Changsha,China.
文摘The layer-dependent properties are still unclarified in two-dimensional(2D)vertical heterostructures.In this study,we layer-bylayer deposited semimetalβ-In2Se3 on monolayer MoS2 to form verticalβ-In2Se3/MoS2 heterostructures by chemical vapor deposition.The defect-mediated nucleation mechanism inducesβ-In2Se3 nanosheets to grow on monolayer MoS2,and the layer number of stackedβ-In2Se3 can be precisely regulated from 1 layer(L)to 13 L by prolonging the growth time.Theβ-In2Se3/MoS2 heterostructures reveal tunable type-Ⅱband alignment arrangement by altering the layer number ofβ-In2Se3,which optimizes the internal electron transfer.Meanwhile,the edge atomic structure ofβ-In2Se3 stacking on monolayer MoS2 shows the reconstruction derived from large lattice mismatch(~29%),and the presence ofβ-In2Se3 also further increases the electrical conductivity ofβ-In2Se3/MoS2 heterostructures.Attributed to abundant layer-dependent edge active sites,edge reconstruction,improved hydrophilicity,and high electrical conductivity ofβ-In2Se3/MoS2 heterostructures,the edge ofβ-In2Se3/MoS2 heterostructures exhibits excellent electrocatalytic hydrogen evolution performance.Lower onset potential and smaller Tafel slope can be observed at the edge of monolayer MoS2 coupled with 13-Lβ-In2Se3.Hence,the outstanding conductive layers coupled with edge reconstruction in 2D vertical heterostructures play decisive roles in the optimization of electron energy levels and improvement of layer-dependent catalytic performance.
基金Acknowledgements This work is supported by the National Natural Science Foundation of China （Nos. 11104010, 61474014, and 51272038）, Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics （No. 20120910）, and the National Basic Research Program of China （No. 2013CB933301）.
文摘Thermal transport in superlattices is governed by various phonon-scattering processes. For extracting the phonon-scattering contribution of hetero-interfaces in chalcogenide superlattices, single-crystalline Bi2Se3/In2Se3 （BS/IS） superlattices with minimized defects are prepared on fluorophlogopite mica by molecular beam epitaxy. The cross-plane heat-conducting properties of the BS/IS superlattices are demonstrated to depend precisely on the period thicknesses and constituents of the superlattices, where a minimum in the thermal conductivity indicates a crossover from particle-like to wave-like phonon transport in the superlattices. The thermal-conductivity minimum of the BS/IS superlattices is nearly one order of magnitude lower than that of intrinsic BS film.
基金financially supported by the National Key Research and Development Program of China (2017YFA0207500)the National Natural Science Foundation of China (61622406, 61571415 and 51502283)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences (XDB30000000)Beijing Academy of Quantum Information Sciences (Y18G04)
文摘Multiferroic materials exhibit tremendous potentials in novel magnetoelectric devices such as high-density non-volatile storage.Herein,we report the coexistence of ferroelectricity and ferromagnetism in two-dimensional Fedoped In2Se3(Fe0.16In1.84Se3,FIS).The Fe atoms were doped at the In atom sites and the Fe content is^3.22%according to the experiments.Our first-principles calculation based on the density-functional theory predicts a magnetic moment of 5μB per Fe atom when Fe substitutes In sites in In2Se3.The theoretical prediction was further confirmed experimentally by magnetic measurement.The results indicate that pure In2Se3 is diamagnetic,whereas FIS exhibits ferromagnetic behavior with a parallel anisotropy at 2 K and a Curie temperature of^8 K.Furthermore,the sample maintains stable room-temperature ferroelectricity in piezoresponse force microscopy(PFM)measurement after the introduction of Fe atom into the ferroelectric In2Se3 nanoflakes.The findings indicate that the layered Fe0.16In1.84Se3 materials have potential in future nanoelectronic,magnetic,and optoelectronic applications.
基金China Postdoctoral Science Foundation,Grant/Award Number:2019M661200National Natural Science Foundation of China,Grant/Award Numbers:11874171,11904118,61922035Fundamental Research Funds for the Central Universities。
文摘Ferroelectric memory is a promising candidate for next-generation nonvolatile memory owing to its outstanding performance such as low power consump-tion,fast speed,and high endurance.However,the ferroelectricity of conven-tional ferroelectric materials will be eliminated by the depolarization field when the size drops to the nanometer scale.As a result,the miniaturization of ferroelectric devices was hindered,which makes ferroelectric memory unable to keep up with the development of integrated-circuit(IC)miniaturization.Recently,a two-dimensional(2D)In2Se3 was reported to maintain stable ferro-electricity at the ultrathin scale,which is expected to break through the bottle-neck of miniaturization.Soon,devices based on 2D In2Se3,including the ferroelectric field-effect transistor,ferroelectric channel transistor,synaptic fer-roelectric semiconductor junction,and ferroelectric memristor were demon-strated.However,a comprehensive understanding of the structures and the ferroelectric-switching mechanism of 2D In2Se3 is still lacking.Here,the atomic structures of different phases,the dynamic mechanism of ferroelectric switching,and the performance/functions of the latest devices of 2D In2Se3 are reviewed.Furthermore,the correlations among the structures,the properties,and the device performance are analyzed.Finally,several crucial problems or challenges and possible research directions are put forward.We hope that this review paper can provide timely knowledge and help for the research commu-nity to develop 2D In2Se3 based ferroelectric memory and computing technol-ogy for practical industrial applications.
基金supported by the National Natural Science Foundation of China(11974307,61574123,11674299,and 11634011)National Key Research and Development Program of China(2017YFA0204904)+3 种基金Fundamental Research Funds for the Central Universities(2019FZA3004,WK2340000082,and WK2060190084)Zhejiang Provincial Natural Science Foundation(D19A040001)Anhui Initiative in Quantum Information Technologies(AHY170000)Strategic Priority Research Program of Chinese Academy of Sciences(XDB30000000)。
文摘The electric control of magnetic properties based on magnetoelectric effect is crucial for the development of future data storage devices.Here,based on first-principles calculations,a strong magnetoelectric effect is proposed to effectively switch on/off the magnetic states as well as alter the in-plane/perpendicular easy axes of metal-phthalocyanine molecules(MPc)by reversing the electric polarization of the underlying two-dimensional(2D)ferroelectric a-In2Se3 substrate with the application of an external electric field.The mechanism originates from the different hybridization between the molecule and the ferroelectric substrate in which the different electronic states of surface Se layer play a dominant role.Moreover,the magnetic moments and magnetic anisotropy energies(MAE)of OsPc/In2Se3 can be further largely enhanced by a functionalized atom atop the OsPc molecule.The I-OsPc/In2Se3 system possesses large MAE up to 30 meV at both polarization directions,which is sufficient for room-temperature applications.These findings provide a feasible scheme to realize ferroelectric control of magnetic states in 2D limit,which have great potential for applications in nanoscale electronics and spintronics.
文摘With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Gao Chunxiao(高春晓)from the State Key Laboratory for Superhard Materials,Institute of Atomic and Molecular Physics,Jilin University and Prof.Chen Bin from the
基金We highly acknowledge Queensland Univer-sity of Technology(QUT)and National Computational Infrastruc-ture(NC)Australia for providing high performance computing(HPC)facilities to undertake this project.
文摘Favourable band alignment and excellent visible light response are vital for photochemical water splitting.In this work,we have theoretically investigated how ferroelectric polarization and its reversibility in direction can be utilized to modulate the band alignment and optical absorption properties.For this objective,2D van der Waals heterostructures(HTSs)are constructed by interfacing monolayer M0 S2 with ferroelectric In2 Se3.We find the switch of polarization direction has dramatically changed the band alignment,thus facilitating different type of reactions.In Iri2 Se3/MoS2/In2 Se3 heterostructures,one polarization direction supports hydrogen evolution reaction and another polarization direction can favour oxygen evolution reaction.These can be used to create tuneable photocatalyst materials where water reduction reactions can be selectively controlled by polarization switching.The modulation of band alignment is attributed to the shift of reaction potential caused by spontaneous polarization.Additionally,the formed type-II van der Waals HTSs also significantly improve charge separation and enhance the optical absorption in the visible and infrared regions.Our results pave a way in the design of van der Waals HTSs for water splitting using ferroelectric materials.
