The research of ultraviolet photodetectors(UV PDs)have been attracting extensive attention,due to their important applications in many areas.In this study,PtSe2/GaN heterojunction is in-situ fabricated by synthesis of...The research of ultraviolet photodetectors(UV PDs)have been attracting extensive attention,due to their important applications in many areas.In this study,PtSe2/GaN heterojunction is in-situ fabricated by synthesis of large-area vertically standing two-dimensional(2D)PtSe2 film on n-GaN substrate.The PtSe2/GaN heterojunction device demonstrates excellent photoresponse properties under illumination by deep UV light of 265 nm at zero bias voltage.Further analysis reveals that a high responsivity of 193 mA·W^-1,an ultrahigh specific detectivity of 3.8 × 10^14 Jones,linear dynamic range of 155d B and current on/off ratio of^10^8,as well as fast response speeds of 45/102μs were obtained at zero bias voltage.Moreover,this device response quickly to the pulse laser of 266 nm with a rise time of 172 ns.Such high-performanee PtSe2/GaN heteroj u nction UV PD demonstrated in this work is far superior to previously reported results,suggesting that it has great potential for deep UV detection.展开更多
Platinum diselenide(PtSe2)is a promising transition metal dichalcogenide(TMDC)material with unique properties.It is necessary to find a controllable fabrication method to bridge PtSe2 with other two-dimensional(2D)mat...Platinum diselenide(PtSe2)is a promising transition metal dichalcogenide(TMDC)material with unique properties.It is necessary to find a controllable fabrication method to bridge PtSe2 with other two-dimensional(2D)materials for practical applications,which has rarely been reported so far.Here,we report that the selenization of Pt(111)can be suppressed to form a Se intercalated layer,instead of a PtSe2 monolayer,by inducing confined conditions with a precoating of graphene.Experiments with graphene-island samples demonstrate that the monolayer PtSe2 can be controllably fabricated only on the bare Pt surface,while the Se intercalated layer is formed underneath graphene,as verified by atomic-resolution observations with scanning transmission electron microscopy(STEM)and scanning tunneling microscopy(STM).In addition,the orientation of the graphene island shows a negligible influence on the Se intercalated layer induced by the graphene coating.By extending the application of 2D confined reactions,this work provides a new method to control the fabrication and pattern 2D materials during the fabrication process.展开更多
Transition metal dichalcogenides(TMDs)have emerged as a promising electrocatalyst for hydrogen evo-lution reaction(HER)due to its excellent conductivity and abundant electrocatalytic active sites of its edges.TMDs nan...Transition metal dichalcogenides(TMDs)have emerged as a promising electrocatalyst for hydrogen evo-lution reaction(HER)due to its excellent conductivity and abundant electrocatalytic active sites of its edges.TMDs nanowall can expose abundant of edges so that they tend to show better catalytic performance for hydrogen evolution reaction.Herein,PtSe_(2) nanowall films with morphology controlled at centimeters level are synthesized by selenizing Pt film.The dynamic and thermodynamics of selenation reaction are investigated.The nanowall structure can be obtained by controlling the growth temperature,and the thickness of nanowall can be tuned by the original thickness of Pt film.The Pt atoms can be rearranged into ordered distribution at 550℃ and can be induced to well-ordered PtSe_(2) nanowalls finally.The well-ordered PtSe_(2) nanowall films show excellent HER performance,with an overpotential of 0.3 V at-10 mA·cm^(-2) and a Tafel slope of~52 mV·dec^(-1).This work demonstrates the great potential of activated 2D PtSe_(2) as an ultrathin film catalyst for the HER,which is valuable to provide instruction and afford experience for further application at industrial level.展开更多
1T phase of transition metal dichalcogenides(TMDCs)formed by group 10 transition metals(e.g.Pt,Pd)have attracted increasing interests due to their novel properties and potential device applications.Synthesis of large ...1T phase of transition metal dichalcogenides(TMDCs)formed by group 10 transition metals(e.g.Pt,Pd)have attracted increasing interests due to their novel properties and potential device applications.Synthesis of large scale thin films with controlled phase is critical especially considering that these materials have relatively strong interlayer interaction and are difficult to exfoliate.Here we report the growth of centimeter-scale PtTe,1T-PtTe2 and 1T-PtSe2 films via direct deposition of Pt metals followed by tellurization or selenization.We find that by controlling the Te flux,a hitherto-unexplored PtTe phase can also be obtained,which can be further tuned into PtTe2 by high temperature annealing under Te flux.These films with different thickness can be grown on a wide range of substrates,including NaCl which can be further dissolved to obtain free-standing PtTe2 or PtSe2 films.Moreover,a systematic thickness dependent resistivity and Hall conductivity measurements show that distinguished from the semiconducting PtSe2 with hole carriers,PtTe2 and PtTe films are metallic.Our work opens new opportunities for investigating the physical properties and potential applications of group 10 TMDC films and the new monochalcogenide PtTe film.展开更多
With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to...With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to electrodes,of TMD heterostructure devices can be significantly tailored by employing the functional layers,called interlayer engineering.At the interface between different TMD layers,the dangling-bond states normally exist and act as traps against charge carrier flow.In this study,we propose a technique to suppress such carrier trap that uses enhanced interlayer hybridization to saturate dangling-bond states,as demonstrated in a strongly interlayer-coupled monolayer-bilayer PtSe2 heterostructure.The hybridization between the unsaturated states and the interlayer electronic states of PtSe2 significantly reduces the depth of carrier traps at the interface,as corroborated by our scanning tunnelling spectroscopic measurements and density functional theory calculations.The suppressed interfacial trap demonstrates that interlayer saturation may offer an efficient way to relay the charge flow at the interface of TMD heterostructures.Thus,this technique provides an effective way for optimizing the interface contact,the crucial issue exists in two-dimensional electronic community.展开更多
基金the National Natural Science Foundation of China(Nos.61605174 and 61774136)the Key Projects of Higher Education in Henan Province(No.17A140012)Research Grants Council,University Grants Committee(RGC,UGC)(GRF 152109/16E PolyU B-Q52T).
文摘The research of ultraviolet photodetectors(UV PDs)have been attracting extensive attention,due to their important applications in many areas.In this study,PtSe2/GaN heterojunction is in-situ fabricated by synthesis of large-area vertically standing two-dimensional(2D)PtSe2 film on n-GaN substrate.The PtSe2/GaN heterojunction device demonstrates excellent photoresponse properties under illumination by deep UV light of 265 nm at zero bias voltage.Further analysis reveals that a high responsivity of 193 mA·W^-1,an ultrahigh specific detectivity of 3.8 × 10^14 Jones,linear dynamic range of 155d B and current on/off ratio of^10^8,as well as fast response speeds of 45/102μs were obtained at zero bias voltage.Moreover,this device response quickly to the pulse laser of 266 nm with a rise time of 172 ns.Such high-performanee PtSe2/GaN heteroj u nction UV PD demonstrated in this work is far superior to previously reported results,suggesting that it has great potential for deep UV detection.
基金We acknowledge financial support from the National Key Research and Development Program of China(Nos.2016YFA0202300 and 2018YFA0305800)the National Natural Science Foundation of China(Nos.61725107 and 61971035)+1 种基金Beijing Natural Science Foundation(Nos.4192054 and Z190006)Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB30000000 and XDB28000000).
文摘Platinum diselenide(PtSe2)is a promising transition metal dichalcogenide(TMDC)material with unique properties.It is necessary to find a controllable fabrication method to bridge PtSe2 with other two-dimensional(2D)materials for practical applications,which has rarely been reported so far.Here,we report that the selenization of Pt(111)can be suppressed to form a Se intercalated layer,instead of a PtSe2 monolayer,by inducing confined conditions with a precoating of graphene.Experiments with graphene-island samples demonstrate that the monolayer PtSe2 can be controllably fabricated only on the bare Pt surface,while the Se intercalated layer is formed underneath graphene,as verified by atomic-resolution observations with scanning transmission electron microscopy(STEM)and scanning tunneling microscopy(STM).In addition,the orientation of the graphene island shows a negligible influence on the Se intercalated layer induced by the graphene coating.By extending the application of 2D confined reactions,this work provides a new method to control the fabrication and pattern 2D materials during the fabrication process.
基金the National Natural Science Foundation of China(No.51802266)Shaanxi’s Key Project of Research and Development Plan(No.2021GY-217)+1 种基金the Research Funds for Interdisciplinary Subject of NWPU(No.19SH0304)the Fundamental Research Funds for the Central Universities(No.3102017jc01001)。
文摘Transition metal dichalcogenides(TMDs)have emerged as a promising electrocatalyst for hydrogen evo-lution reaction(HER)due to its excellent conductivity and abundant electrocatalytic active sites of its edges.TMDs nanowall can expose abundant of edges so that they tend to show better catalytic performance for hydrogen evolution reaction.Herein,PtSe_(2) nanowall films with morphology controlled at centimeters level are synthesized by selenizing Pt film.The dynamic and thermodynamics of selenation reaction are investigated.The nanowall structure can be obtained by controlling the growth temperature,and the thickness of nanowall can be tuned by the original thickness of Pt film.The Pt atoms can be rearranged into ordered distribution at 550℃ and can be induced to well-ordered PtSe_(2) nanowalls finally.The well-ordered PtSe_(2) nanowall films show excellent HER performance,with an overpotential of 0.3 V at-10 mA·cm^(-2) and a Tafel slope of~52 mV·dec^(-1).This work demonstrates the great potential of activated 2D PtSe_(2) as an ultrathin film catalyst for the HER,which is valuable to provide instruction and afford experience for further application at industrial level.
基金the National Natural Science Foundation of China(Nos.11725418 and 21975140)the National Key Basic Research Program of China(Nos.2015CB921001,2016YFA0301001 and 2016YFA0301004)+2 种基金Science Challenge Project(No.TZ20164500122)the Basic Science Center Program of NSFC(No.51788104)Beijing Advanced Innovation Center of Future Chip(ICFC)and Tsinghua University Initiative Scientific Research Program.
文摘1T phase of transition metal dichalcogenides(TMDCs)formed by group 10 transition metals(e.g.Pt,Pd)have attracted increasing interests due to their novel properties and potential device applications.Synthesis of large scale thin films with controlled phase is critical especially considering that these materials have relatively strong interlayer interaction and are difficult to exfoliate.Here we report the growth of centimeter-scale PtTe,1T-PtTe2 and 1T-PtSe2 films via direct deposition of Pt metals followed by tellurization or selenization.We find that by controlling the Te flux,a hitherto-unexplored PtTe phase can also be obtained,which can be further tuned into PtTe2 by high temperature annealing under Te flux.These films with different thickness can be grown on a wide range of substrates,including NaCl which can be further dissolved to obtain free-standing PtTe2 or PtSe2 films.Moreover,a systematic thickness dependent resistivity and Hall conductivity measurements show that distinguished from the semiconducting PtSe2 with hole carriers,PtTe2 and PtTe films are metallic.Our work opens new opportunities for investigating the physical properties and potential applications of group 10 TMDC films and the new monochalcogenide PtTe film.
基金We acknowledged the financial support from the Beijing Natural Science Foundation(Nos.Z190006 and 4192054)the National Natural Science Foundation of China(Nos.61725107,11622437,61674171,11974422,61761166009,and 61888102)+3 种基金the National Key Research&Development Projects of China(Nos.2016YFA0202301,2019YFA0308000,and 2018YFE0202700)the Fundamental Research Funds for the Central Universities,China and the Research Funds of Renmin University of China(Nos.16XNLQ01 and 19XNQ025)the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB30000000 and XDB28000000)Calculations were performed at the Physics Lab of High-Performance Computing of Renmin University of China and Shanghai Supercomputer Center.
文摘With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to electrodes,of TMD heterostructure devices can be significantly tailored by employing the functional layers,called interlayer engineering.At the interface between different TMD layers,the dangling-bond states normally exist and act as traps against charge carrier flow.In this study,we propose a technique to suppress such carrier trap that uses enhanced interlayer hybridization to saturate dangling-bond states,as demonstrated in a strongly interlayer-coupled monolayer-bilayer PtSe2 heterostructure.The hybridization between the unsaturated states and the interlayer electronic states of PtSe2 significantly reduces the depth of carrier traps at the interface,as corroborated by our scanning tunnelling spectroscopic measurements and density functional theory calculations.The suppressed interfacial trap demonstrates that interlayer saturation may offer an efficient way to relay the charge flow at the interface of TMD heterostructures.Thus,this technique provides an effective way for optimizing the interface contact,the crucial issue exists in two-dimensional electronic community.
基金supported by the National Natural Science Foundation of China(62090030/62090031,51872257,and 51672244)the National Key R&D Program of China(2021YFA1200502)the Natural Science Foundation of Zhejiang Province,China(LZ20F040001)。
文摘因二维材料的独特性质及其可调谐的光谱响应,基于二维材料的光电探测器受到广泛关注.然而,它们的性能还不够突出,其制造工艺与硅基互补金属氧化物半导体技术工艺流程的兼容性还需要评估.在本文中,我们报道了一种基于二硒化铂/超薄二氧化硅/硅异质结构的高性能、空气稳定、自驱动、室温宽带光电探测器.该光电探测器表现出超高的响应度(8.06 AW-1)和比探测率(4.78×10^(13)cm Hz^(1/2)W^(-1))、极低的暗电流(0.12 pA)以及优秀的开关比(1.29×10^(9)).在375,532,1342和1550 nm波长处所测的光电流响应度分别为2.12,5.56,18.12和0.65 m AW^(-1).此外,制造的9×9器件阵列不仅展示了该探测器非常好的均匀性和可重复性,而且还显示了其在紫外-可见-近红外照明成像应用领域的潜力.我们设计的二硒化铂/超薄二氧化硅/硅异质结光电探测器极大地抑制了暗电流,提高了二极管的理想因子并增加了界面势垒.因此,它为改善光电探测器性能的设计提供了一种新策略.
