范德华异质结是二维材料的研究前沿及热点,特别是它的能带对齐方式,因为它决定异质结基本的电子性质.利用基于密度泛函理论的第一性原理方法,本文对过渡金属二硫化物PtSe_(2)/MoSe_(2)异质结的结构特性与电子结构进行了系统研究.计算的...范德华异质结是二维材料的研究前沿及热点,特别是它的能带对齐方式,因为它决定异质结基本的电子性质.利用基于密度泛函理论的第一性原理方法,本文对过渡金属二硫化物PtSe_(2)/MoSe_(2)异质结的结构特性与电子结构进行了系统研究.计算的结合能和声子谱、分子动力学模拟以及力学性质研究表明,PtSe_(2)/MoSe_(2)异质结是高度稳定的,其实验制备是可行的.我们发现这种异质结具有与目前众多研究的异质结不同的特殊的V-型能带对齐这是因为与2D界面垂直的能量相近的MoSe_(2)层Se-pz轨道、Mo-dz2轨道与PtSe_(2)层的Se-pz轨道存在层间耦合,诱发离域的价带最大(Valance Band Maximum,VBM)杂化态.此外,我们也检验了该V-型能带对齐在各种物理场(外电场、应变)耦合下的稳定性,发现异质结的VBM和导带最小(Conduction Band Minimum,CBM)对外部物理场耦合具有完全不同的响应.在较小的负电场下以及整个正电场范围内,或在较小的垂直拉伸下和整个垂直压缩应变范围内,两单层的VBM仍保持较强的轨道耦合,不因物理场效应而消除,导致PtSe_(2)和MoSe_(2)层的VBM态同步非常规移动,从而使异质结始终保持V-型能带对齐.这一新颖的非常规的能带对齐方式呈现高稳定性,对于研发基于PtSe_(2)/MoSe_(2)异质结的特殊的高性能光电器件具有巨大的应用潜力.展开更多
Optical bistability can be used to explore key components of all-optical information processing systems,such as optical switches and optical random memories.The hybrid integration of emerged two-dimensional layered Pt...Optical bistability can be used to explore key components of all-optical information processing systems,such as optical switches and optical random memories.The hybrid integration of emerged two-dimensional layered PtSe_(2)with waveguides is promising for the applications.We demonstrated the optical bistability in the PtSe_(2)-on-silicon nitride microring resonator induced by a thermo-optic effect.The fabricated device has a resonance-increasing rate of 6.8 pm/mW with increasing optical power.We also established a theoretical model to explain the observation and analyze the device's performance.The study is expected to provide a new scheme for realizing all-optical logic devices in next-generation information processing systems.展开更多
Two-dimensional(2D)layered materials have attracted extensive research interest in the field of high-performance photodetection due to their high carrier mobility,tunable bandgap,stability,other excellent properties.H...Two-dimensional(2D)layered materials have attracted extensive research interest in the field of high-performance photodetection due to their high carrier mobility,tunable bandgap,stability,other excellent properties.Herein,we propose a gate-tunable,high-performance,self-driving,wide detection range phototransistor based on a 2D PtSe_(2)on silicon-oninsulator(SOI).Benefiting from the strong built-in electric field of the PtSe_(2)/Si heterostructure,the phototransistor has a fast response time(rise/fall time)of 36.7/32.6μs.The PtSe_(2)/Si phototransistor exhibits excellent photodetection performance over a broad spectral range from ultraviolet to near-infrared,including a responsivity of 1.07 A/W and a specific detectivity of 6.60×10^(9)Jones under 808 nm illumination at zero gate voltage.The responsivity and specific detectivity of PtSe_(2)/Si phototransistor at 5 V gate voltage are increased to 13.85 A/W and 1.90×10^(10) Jones under 808 nm illumination.Furthermore,the fabricated PtSe_(2)/Si phototransistor array shows excellent uniformity,reproducibility,long-term stability in terms of photoresponse performance with negligible variation between pixel cells.The architecture of present PtSe_(2)/Si on SOI platform paves a new way of a general strategy to realize high-performance photodetectors by combining the advantages of both 2D materials and conventional semiconductors which is compatible with current Si-complementary metal oxide semiconductor(CMOS)process.展开更多
This study proposes a feasible and scalable production strategy to naturally obtain aligned platinum diselenide(PtSe_(2))nanoribbon arrays with anisotropic conductivity.The anisotropic properties of two-dimensional(2D...This study proposes a feasible and scalable production strategy to naturally obtain aligned platinum diselenide(PtSe_(2))nanoribbon arrays with anisotropic conductivity.The anisotropic properties of two-dimensional(2D)materials,especially transition-metal dichalcogenides(TMDs),have attracted great interest in research.The dependence of physical properties on their lattice orientations is of particular interest because of its potential in diverse applications,such as nanoelectronics and optoelectronics.One-dimensional(1D)nanostructures facilitate many feasible production strategies for shaping 2D materials into unidirectional 1D nanostructures,providing methods to investigate the anisotropic properties of 2D materials based on their lattice orientations and dimensionality.The natural alignment of zigzag(ZZ)PtSe_(2) nanoribbons is experimentally demonstrated using angle-resolved polarized Raman spectroscopy(ARPRS),and the selective growth mechanism is further theoretically revealed by comparing edges and edge energies of different orientations using the density functional theory(DFT).Back-gate field-effect transistors(FETs)are also constructed of unidirectional PtSe_(2) nanoribbons to investigate their anisotropic electrical properties,which align with the results of the projected density of states(DOS)calculations.This work provides new insight into the anisotropic properties of 2D materials and a feasible investigation strategy from experimental and theoretical perspectives.展开更多
The large tunability in the band structure is ubiquitous in two-dimensional(2D)materials,and PtSe_(2) is not an exception,which has attracted considerable attention in electronic and optoelectronic applications due to...The large tunability in the band structure is ubiquitous in two-dimensional(2D)materials,and PtSe_(2) is not an exception,which has attracted considerable attention in electronic and optoelectronic applications due to its high carrier mobility and long-term airstability.Such dimensional dependent properties are closely related to the evolution of electronic band structures.Critical points(CPs),the extrema or saddle points of electronic bands,are the cornerstone of condensed-matter physics and fundamentally determine the optical and transport phenomena of the layered PtSe_(2).Here,we have experimentally revealed the detailed electronic structures in layered PtSe_(2),including the CPs in the Brillouin zones(BZs),by means of reflection contrast spectroscopy and spectroscopic ellipsometry(SE).There are three critical points in the BZs attributed to the excitonic transition,quasi-particle band gap,and the band nesting effect related transition,respectively.Three CPs show red-shifting trends with increasing layer number under the mechanism of strong interlayer coupling.We have further revealed the electron–phonon(e–ph)interaction in such layered material,utilizing temperature-dependent absorbance spectroscopy.The strength of e–ph interaction and the average phonon energy also decline with the increasement of layer number.Our findings give a deep understanding to the physics of the layer-dependent evolution of the electronic structure of PtSe_(2),potentially leading to applications in optoelectronics and electronic devices.展开更多
Grain boundaries in two-dimensional(2D)semiconductors generally induce distorted band alignment and interfacial charge,which impair their electronic properties for device applications.Here,we report the improvement of...Grain boundaries in two-dimensional(2D)semiconductors generally induce distorted band alignment and interfacial charge,which impair their electronic properties for device applications.Here,we report the improvement of band alignment at the grain boundaries of PtSe_(2),a 2D semiconductor,with selective adsorption of a presentative organic acceptor,tetracyanoquinodimethane(TCNQ).TCNQ molecules show selective adsorption at the PtSe_(2)grain boundary with strong interfacial charge.The adsorption of TCNQ distinctly improves the band alignment at the PtSe_(2)grain boundaries.With the charge transfer between the grain boundary and TCNQ,the local charge is inhibited,and the band bending at the grain boundary is suppressed,as revealed by the scanning tunneling microscopy and spectroscopy(STM/S)results.Our finding provides an effective method for the advancement of the band alignment at the grain boundary by functional molecules,improving the electronic properties of 2D semiconductors for their future applications.展开更多
基于二维材料范德华异质结的自驱动光电探测器是逻辑光电子器件和智能图像传感器的重要组成部分.本文通过机械剥离和干法转移制备了一种底部Au接触的PtSe_(2)/WSe_(2)/Au非对称肖特基光电二极管.栅极可调的Au/WSe_(2)肖特基势垒大小、...基于二维材料范德华异质结的自驱动光电探测器是逻辑光电子器件和智能图像传感器的重要组成部分.本文通过机械剥离和干法转移制备了一种底部Au接触的PtSe_(2)/WSe_(2)/Au非对称肖特基光电二极管.栅极可调的Au/WSe_(2)肖特基势垒大小、弱费米钉扎效应、高半金属PtSe_(2)导电率以及良好的PtSe_(2)/WSe_(2)层间耦合效应使得该二极管产生极性可重构现象,可实现栅极可调正负整流行为,且整流比变化范围在10−2到104之间,达到6个量级.我们利用此特性验证了半波逻辑整流器功能.此外,此自驱动器件的最大光响应度达316 mA W^(−1),最大光开关比达105,光电转换效率为4.62%,响应时间仅为830/950μs.光电流微区扫描结果表明,器件的光电流主要分布在Au/WSe_(2)界面边缘,证实该器件为非对称肖特基光电二极管.该器件还实现了高分辨率的可见光单点成像.上述研究结果表明,本工作为制备高性能半波整流器、超快自驱动光电探测器和高分辨图像传感器提供了一种简便有效的策略.展开更多
An emerging subclass of transition-metal dichalcogenides(TMDs),noble-transition-metal dichalcogenides(NMDs),has led to an increase in nanoscientific research in two-dimensional(2D)materials.NMDs feature a unique struc...An emerging subclass of transition-metal dichalcogenides(TMDs),noble-transition-metal dichalcogenides(NMDs),has led to an increase in nanoscientific research in two-dimensional(2D)materials.NMDs feature a unique structure and several useful properties.2D NMDs are promising candidates for a broad range of applications in areas such as photodetectors,phototransistors,saturable absorbers,and meta optics.In this review,the state of the art of 2D NMDs research,their structures,properties,synthesis,and potential applications are discussed,and a perspective of expected future developments is provided.展开更多
文摘范德华异质结是二维材料的研究前沿及热点,特别是它的能带对齐方式,因为它决定异质结基本的电子性质.利用基于密度泛函理论的第一性原理方法,本文对过渡金属二硫化物PtSe_(2)/MoSe_(2)异质结的结构特性与电子结构进行了系统研究.计算的结合能和声子谱、分子动力学模拟以及力学性质研究表明,PtSe_(2)/MoSe_(2)异质结是高度稳定的,其实验制备是可行的.我们发现这种异质结具有与目前众多研究的异质结不同的特殊的V-型能带对齐这是因为与2D界面垂直的能量相近的MoSe_(2)层Se-pz轨道、Mo-dz2轨道与PtSe_(2)层的Se-pz轨道存在层间耦合,诱发离域的价带最大(Valance Band Maximum,VBM)杂化态.此外,我们也检验了该V-型能带对齐在各种物理场(外电场、应变)耦合下的稳定性,发现异质结的VBM和导带最小(Conduction Band Minimum,CBM)对外部物理场耦合具有完全不同的响应.在较小的负电场下以及整个正电场范围内,或在较小的垂直拉伸下和整个垂直压缩应变范围内,两单层的VBM仍保持较强的轨道耦合,不因物理场效应而消除,导致PtSe_(2)和MoSe_(2)层的VBM态同步非常规移动,从而使异质结始终保持V-型能带对齐.这一新颖的非常规的能带对齐方式呈现高稳定性,对于研发基于PtSe_(2)/MoSe_(2)异质结的特殊的高性能光电器件具有巨大的应用潜力.
基金supported by the National Natural Science Foundation of China(Nos.62161160335 and 62175179)the Natural Science Foundation of Guangdong Province,China(Nos.2023A1515011189 and 2022B1515130002)+2 种基金the Natural Science Foundation of Tianjin Municipality,China(No.23JCJQJC00250)the Hong Kong Research Grants Council Research Grants(No.N_CUHK423/21)the Science and Technology Plan Project of Shenzhen(No.JCYJ20230808105007015).
文摘Optical bistability can be used to explore key components of all-optical information processing systems,such as optical switches and optical random memories.The hybrid integration of emerged two-dimensional layered PtSe_(2)with waveguides is promising for the applications.We demonstrated the optical bistability in the PtSe_(2)-on-silicon nitride microring resonator induced by a thermo-optic effect.The fabricated device has a resonance-increasing rate of 6.8 pm/mW with increasing optical power.We also established a theoretical model to explain the observation and analyze the device's performance.The study is expected to provide a new scheme for realizing all-optical logic devices in next-generation information processing systems.
基金the National Natural Science Foundation of China(Nos.62090030/62090031,51872257,51672244,and 62274145)the National Key R&D Program of China(No.2021YFA1200502)+1 种基金the Natural Science Foundation of Zhejiang Province(No.LZ20F040001)the Zhejiang Province Key R&D Pprogram(No.2020C01120).
文摘Two-dimensional(2D)layered materials have attracted extensive research interest in the field of high-performance photodetection due to their high carrier mobility,tunable bandgap,stability,other excellent properties.Herein,we propose a gate-tunable,high-performance,self-driving,wide detection range phototransistor based on a 2D PtSe_(2)on silicon-oninsulator(SOI).Benefiting from the strong built-in electric field of the PtSe_(2)/Si heterostructure,the phototransistor has a fast response time(rise/fall time)of 36.7/32.6μs.The PtSe_(2)/Si phototransistor exhibits excellent photodetection performance over a broad spectral range from ultraviolet to near-infrared,including a responsivity of 1.07 A/W and a specific detectivity of 6.60×10^(9)Jones under 808 nm illumination at zero gate voltage.The responsivity and specific detectivity of PtSe_(2)/Si phototransistor at 5 V gate voltage are increased to 13.85 A/W and 1.90×10^(10) Jones under 808 nm illumination.Furthermore,the fabricated PtSe_(2)/Si phototransistor array shows excellent uniformity,reproducibility,long-term stability in terms of photoresponse performance with negligible variation between pixel cells.The architecture of present PtSe_(2)/Si on SOI platform paves a new way of a general strategy to realize high-performance photodetectors by combining the advantages of both 2D materials and conventional semiconductors which is compatible with current Si-complementary metal oxide semiconductor(CMOS)process.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(Nos.52072204 and 62104017)the National Postdoctoral Program for Innovative Talents of China(No.BX20200049)China Postdoctoral Science Foundation(No.2021M690013).
文摘This study proposes a feasible and scalable production strategy to naturally obtain aligned platinum diselenide(PtSe_(2))nanoribbon arrays with anisotropic conductivity.The anisotropic properties of two-dimensional(2D)materials,especially transition-metal dichalcogenides(TMDs),have attracted great interest in research.The dependence of physical properties on their lattice orientations is of particular interest because of its potential in diverse applications,such as nanoelectronics and optoelectronics.One-dimensional(1D)nanostructures facilitate many feasible production strategies for shaping 2D materials into unidirectional 1D nanostructures,providing methods to investigate the anisotropic properties of 2D materials based on their lattice orientations and dimensionality.The natural alignment of zigzag(ZZ)PtSe_(2) nanoribbons is experimentally demonstrated using angle-resolved polarized Raman spectroscopy(ARPRS),and the selective growth mechanism is further theoretically revealed by comparing edges and edge energies of different orientations using the density functional theory(DFT).Back-gate field-effect transistors(FETs)are also constructed of unidirectional PtSe_(2) nanoribbons to investigate their anisotropic electrical properties,which align with the results of the projected density of states(DOS)calculations.This work provides new insight into the anisotropic properties of 2D materials and a feasible investigation strategy from experimental and theoretical perspectives.
基金supported by the National Key Research and Development Program of China(No.2021YFB2012601)the Fudan University-CIOMP Joint Fund(No.FC2019-006).
文摘The large tunability in the band structure is ubiquitous in two-dimensional(2D)materials,and PtSe_(2) is not an exception,which has attracted considerable attention in electronic and optoelectronic applications due to its high carrier mobility and long-term airstability.Such dimensional dependent properties are closely related to the evolution of electronic band structures.Critical points(CPs),the extrema or saddle points of electronic bands,are the cornerstone of condensed-matter physics and fundamentally determine the optical and transport phenomena of the layered PtSe_(2).Here,we have experimentally revealed the detailed electronic structures in layered PtSe_(2),including the CPs in the Brillouin zones(BZs),by means of reflection contrast spectroscopy and spectroscopic ellipsometry(SE).There are three critical points in the BZs attributed to the excitonic transition,quasi-particle band gap,and the band nesting effect related transition,respectively.Three CPs show red-shifting trends with increasing layer number under the mechanism of strong interlayer coupling.We have further revealed the electron–phonon(e–ph)interaction in such layered material,utilizing temperature-dependent absorbance spectroscopy.The strength of e–ph interaction and the average phonon energy also decline with the increasement of layer number.Our findings give a deep understanding to the physics of the layer-dependent evolution of the electronic structure of PtSe_(2),potentially leading to applications in optoelectronics and electronic devices.
基金supported by the National Natural Science Foundation of China(62090030/62090031,51872257,51672244,and 62274145)the National Key R&D Program of China(2021YFA1200502)+1 种基金the Natural Science Foundation of Zhejiang Province(LZ20F040001)Zhejiang Province Key R&D programs(2020C01120)。
文摘二维(2D)材料正被广泛用于宽带响应光电探测器(PD).然而,基于2D材料的宽带响应PD通常对红外波长的响应较差.在此,我们报告了垂直PtSe_(2)/超薄Al_(2)O_(3)/Ge PD在近红外照明下的优异光响应性能.我们直接硒化沉积在Al_(2)O_(3)/Ge上的Pt膜以形成PtSe_(2)层.超薄Al_(2)O_(3)钝化层起到表面改性的作用,有效地削弱了光生载流子的复合.在1550 nm的光照下,我们的PtSe_(2)/超薄Al_(2)O_(3)/Ge PD的工作面积为50μm×50μm,并在零偏压下获得了4.09 A W^(-1)、32.6/18.9μs的大响应度和快速上升/下降时间.在-5 V的外加电压下,PtSe_(2)/超薄Al_(2)O_(3)/Ge PD的响应度和响应速度分别高达38.18 A W^(-1)和9.6/7.7μs.我们发现器件的工作面积对光响应特性有很大的影响.此外,我们证明PtSe_(2)/超薄Al_(2)O_(3)/Ge PD阵列在室温下显示出了优异的紫外、可见光和红外成像能力.我们的研究表明,PtSe_(2)/超薄Al_(2)O_(3)/Ge异质结在设计具有优异近红外响应性能的新兴宽带光电子器件方面具有巨大的应用前景.
基金the National Key Research and Development Program of China(Nos.2021YFA1400100,2020YFA0308800,and 2019YFA0308000)the National Natural Science Foundation of China(Nos.92163206 and 62171035)+2 种基金the Beijing Nova Program from Beijing Municipal Science&Technology Commission(No.Z211100002121072)the Beijing Natural Science Foundation(Nos.Z190006 and 4192054)Calculations were performed at the Physics Lab of High-Performance Computing of Renmin University of China,and Beijing Super Cloud Computing Center.
文摘Grain boundaries in two-dimensional(2D)semiconductors generally induce distorted band alignment and interfacial charge,which impair their electronic properties for device applications.Here,we report the improvement of band alignment at the grain boundaries of PtSe_(2),a 2D semiconductor,with selective adsorption of a presentative organic acceptor,tetracyanoquinodimethane(TCNQ).TCNQ molecules show selective adsorption at the PtSe_(2)grain boundary with strong interfacial charge.The adsorption of TCNQ distinctly improves the band alignment at the PtSe_(2)grain boundaries.With the charge transfer between the grain boundary and TCNQ,the local charge is inhibited,and the band bending at the grain boundary is suppressed,as revealed by the scanning tunneling microscopy and spectroscopy(STM/S)results.Our finding provides an effective method for the advancement of the band alignment at the grain boundary by functional molecules,improving the electronic properties of 2D semiconductors for their future applications.
基金supported by the National Natural Science Foundation of China (62004071, 62074060, and 62175040)the Science and Technology Program of Guangzhou (202103030001)“The Pearl River Talent Recruitment Program” (2019ZT08X639)
文摘基于二维材料范德华异质结的自驱动光电探测器是逻辑光电子器件和智能图像传感器的重要组成部分.本文通过机械剥离和干法转移制备了一种底部Au接触的PtSe_(2)/WSe_(2)/Au非对称肖特基光电二极管.栅极可调的Au/WSe_(2)肖特基势垒大小、弱费米钉扎效应、高半金属PtSe_(2)导电率以及良好的PtSe_(2)/WSe_(2)层间耦合效应使得该二极管产生极性可重构现象,可实现栅极可调正负整流行为,且整流比变化范围在10−2到104之间,达到6个量级.我们利用此特性验证了半波逻辑整流器功能.此外,此自驱动器件的最大光响应度达316 mA W^(−1),最大光开关比达105,光电转换效率为4.62%,响应时间仅为830/950μs.光电流微区扫描结果表明,器件的光电流主要分布在Au/WSe_(2)界面边缘,证实该器件为非对称肖特基光电二极管.该器件还实现了高分辨率的可见光单点成像.上述研究结果表明,本工作为制备高性能半波整流器、超快自驱动光电探测器和高分辨图像传感器提供了一种简便有效的策略.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(Nos.61874141 and 11904239).
文摘An emerging subclass of transition-metal dichalcogenides(TMDs),noble-transition-metal dichalcogenides(NMDs),has led to an increase in nanoscientific research in two-dimensional(2D)materials.NMDs feature a unique structure and several useful properties.2D NMDs are promising candidates for a broad range of applications in areas such as photodetectors,phototransistors,saturable absorbers,and meta optics.In this review,the state of the art of 2D NMDs research,their structures,properties,synthesis,and potential applications are discussed,and a perspective of expected future developments is provided.
