Van der Waals(vdW)heterostructures based on transition metal dichalcogenides(TMDs)generally possess a type-II band alignment that facilitates the formation of interlayer excitons between constituent monolayers.Manipul...Van der Waals(vdW)heterostructures based on transition metal dichalcogenides(TMDs)generally possess a type-II band alignment that facilitates the formation of interlayer excitons between constituent monolayers.Manipulation of the interlayer excitons in TMD vdW heterostructures holds great promise for the development of excitonic integrated circuits that serve as the counterpart of electronic integrated circuits,which allows the photons and excitons to transform into each other and thus bridges optical communication and signal processing at the integrated circuit.As a consequence,numerous studies have been carried out to obtain deep insight into the physical properties of interlayer excitons,including revealing their ultrafast formation,long population recombination lifetimes,and intriguing spin-valley dynamics.These outstanding properties ensure interlayer excitons with good transport characteristics,and may pave the way for their potential applications in efficient excitonic devices based on TMD vdW heterostructures.At present,a systematic and comprehensive overview of interlayer exciton formation,relaxation,transport,and potential applications is still lacking.In this review,we give a comprehensive description and discussion of these frontier topics for interlayer excitons in TMD vdW heterostructures to provide valuable guidance for researchers in this field.展开更多
Recent advances in twisted van der Waals heterostructure superlattices have emerged as a powerful and attractive platform for exploring novel condensed matter physics due to the interplay between the moirépotenti...Recent advances in twisted van der Waals heterostructure superlattices have emerged as a powerful and attractive platform for exploring novel condensed matter physics due to the interplay between the moirépotential and Coulomb interactions.The moirésuperlattices act as a periodic confinement potential in space to capture interlayer excitons(IXs),resulting in moiréexciton arrays,which provide opportunities for quantum emitters and many-body physics.The observation of moiréIXs in twisted transition-metal dichalcogenide(TMD)heterostructures has recently been widely reported.However,the capture and study of the moiréintralayer excitons based on TMD twisted homobilayer(T-HB)remain elusive.Here,we report the observation of moiréintralayer excitons in a WSe_(2)/WSe_(2) T-HB with a small twist angle by measuring PL spectrum.The multiple split peaks with an energy range of 1.55-1.73 eV are different from that of the monolayer WSe_(2) exciton peaks.The split peaks were caused by the trapping of intralayer excitons via the moirépotential.The confinement effect of the moirépotential on the moiréintralayer excitons was further demonstrated by the changing of temperature,laser power,and valley polarization.Our findings provide a new avenue for exploring new correlated quantum phenomena and their applications.展开更多
Substitutional doping of two-dimensional(2D)transition metal dichalcogenides(TMDs)has been recognized as a promising strategy to tune their optoelectronic properties for a wide array of applications.However,controllab...Substitutional doping of two-dimensional(2D)transition metal dichalcogenides(TMDs)has been recognized as a promising strategy to tune their optoelectronic properties for a wide array of applications.However,controllable doping of TMDs remains a challenging issue due to the natural doping of these materials.Here,we demonstrate the controllable growth of indium-doped p-type WS_(2) monolayers with various doping concentrations via chemical vapor deposition(CVD)of a host tungsten(W)source and indium(In)dopant.Scanning transmission electron microscopy confirmed that In atoms successfully substitute the W atoms in the WS_(2) lattice.Intriguingly,the photoluminescence of the doped sample experiences strong intensity modulation by the doping concentration,which first increases remarkably with an enhancement factor up to~35 and then decreases gradually when further increasing the doping concentration.Such a phenomenon is attributed to the progressive change of the exciton to trion ratio as well as the defect concentration in the doped samples.The assignment was further verified by the electric behavior of the fabricated In-doped WS_(2) field effect transistors,which changes regularly from n-type to bipolar and finally to p-type behavior with increasing doping concentration.The successful growth of p-type monolayer WS_(2) and the dual control of its optical and electrical properties by In doping may provide a promising method to engineer the opto-electronic properties of 2D materials.展开更多
The optoelectronic properties of atomically thin transition metal dichalcogenides(TMDs)are largely influenced by defect populations(DPs).In this work,we fabricate WSmonolayers with different DPs by varying the fabrica...The optoelectronic properties of atomically thin transition metal dichalcogenides(TMDs)are largely influenced by defect populations(DPs).In this work,we fabricate WSmonolayers with different DPs by varying the fabrication methods and further reveal their distinct exciton-exciton interactions.Steady-state photoluminescence(PL)experiments show that the monolayer with the lowest DP shows optimal PL intensity at low excitation power;however,it is overtaken and significantly surpassed by monolayers with higher DPs at high excitation powers.Excitation-power-dependent experiments demonstrate that these monolayers exhibit distinct PL saturation behaviors with the threshold power differing by four orders of magnitude.Combined with in situ PL imaging and time-resolved PL experiments,we attribute such PL evolution discrepancies to the different DPs within these monolayers,which largely influence the exciton diffusion behavior and subsequently bring about distinct nonradiative exciton-exciton annihilations(EEAs).Valley polarization experiments are further employed to re-examine the DPs of these monolayers.This work reveals the distinct PL behaviors and underlying exciton dynamics in TMD monolayers with different DPs,which can largely facilitate the engineering of relevant high-performance devices for practical applications.展开更多
With the unprecedented increasing demand for extremely fast processing speed and huge data capacity,traditional silicon-based information technology is becoming saturated due to the encountered bottle-necks of Moore&#...With the unprecedented increasing demand for extremely fast processing speed and huge data capacity,traditional silicon-based information technology is becoming saturated due to the encountered bottle-necks of Moore's Law.New material systems and new device architectures are considered promising strategies for this challenge.Two-dimensional(2D)materials are layered materials and garnered persistent attention in recent years owing to their advantages in ultrathin body,strong light-matter interaction,flexible integration,and ultrabroad operation wavelength range.To this end,the integra-tion of 2D materials into silicon-based platforms opens a new path for silicon photonic integration.In this work,a comprehensive review is given of the recent signs of progress related to 2D material inte-grated optoelectronic devices and their potential applications in silicon photonics.Firstly,the basic op-tical properties of 2D materials and heterostructures are summarized in the first part.Then,the state-of-the-art three typical 2D optoelectronic devices for silicon photonic applications are reviewed in detail.Finally,the perspective and challenges for the aim of 3D monolithic heterogeneous integration of these 2D optoelectronic devices are discussed.展开更多
Two-dimensional(2D)transition metal dichalcogenides(TMDs)have attracted extensive attention due to their unique electronic and optical properties.In particular,TMDs can be fexibly combined to form diverse vertical van...Two-dimensional(2D)transition metal dichalcogenides(TMDs)have attracted extensive attention due to their unique electronic and optical properties.In particular,TMDs can be fexibly combined to form diverse vertical van der Waals(vdWs)heterostructures without the limitation of lattice matching,which creates vast opportunities for fundamental investigation of novel optoelectronic applications.Here,we report an atomically thin vertical p-n junction WSe_(2)/MoS_(2)produced by a chemical vapor deposition method.Transmission electron microscopy and steady-state photoluminescence experiments reveal its high quality and excellent optical properties.Back gate feld efect transistor(FET)constructed using this p-n junction exhibits bipolar behaviors and a mobility of 9 cm^(2)/(V·s).In addition,the photodetector based on MoS_(2)/WSe_(2)heterostructures displays outstanding optoelectronic properties(R=8 A/W,D^(*)=2.93×10^(11)Jones,on/of ratio of 10^(4)),which benefted from the built-in electric feld across the interface.The direct growth of TMDs p-n vertical heterostructures may ofer a novel platform for future optoelectronic applications.展开更多
基金supported by the National Natural Science Foundation of China(62090035,U19A2090,61905071)the Key Program of the Hunan Provincial Science and Technology Department(2019XK2001,2020XK2001)+2 种基金the International Science and Technology Innovation Cooperation Base of Hunan Province(2018WK4004)the China Postdoctoral Science Foundation(2022TQ0100)the National Key Research and 288 Development Program of China(2022YFB3604701).
基金supported by the National Natural Science Foundation of China(62375079,52072117,62375081,52221001,51972105,62090035,U19A2090,and 61905071)the National Key R&D Program of China(2022YFA1204300)+4 种基金the Key Program of Science and Technology Department of Hunan Province(2019XK2001 and 2020XK2001)the Key Research and Development Plan of Hunan Province(2023GK2012)the Open Project Program of Key Laboratory of Nanodevices and Applications,Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences(22ZS01)the Hunan Provincial Natural Science Foundation of China(2021JJ30132)the China Scholarship Council.
基金The authors are grateful to the National Natural Science Foundation of China(Nos.52072117,21703059,51972105,51525202,61635001,and 61905071)the Joint Funds of the National Natural Science Foundation of China(No.U19A2090)+2 种基金the Key Program of the Hunan Provincial Science and Technology Department(No.2019XK2001)the International Science and Technology Innovation Cooperation Base of Hunan Province(2018WK4004)the Open Project Program of Wuhan National Laboratory for Optoelectronics(No.2020WNLOKF002).
文摘Van der Waals(vdW)heterostructures based on transition metal dichalcogenides(TMDs)generally possess a type-II band alignment that facilitates the formation of interlayer excitons between constituent monolayers.Manipulation of the interlayer excitons in TMD vdW heterostructures holds great promise for the development of excitonic integrated circuits that serve as the counterpart of electronic integrated circuits,which allows the photons and excitons to transform into each other and thus bridges optical communication and signal processing at the integrated circuit.As a consequence,numerous studies have been carried out to obtain deep insight into the physical properties of interlayer excitons,including revealing their ultrafast formation,long population recombination lifetimes,and intriguing spin-valley dynamics.These outstanding properties ensure interlayer excitons with good transport characteristics,and may pave the way for their potential applications in efficient excitonic devices based on TMD vdW heterostructures.At present,a systematic and comprehensive overview of interlayer exciton formation,relaxation,transport,and potential applications is still lacking.In this review,we give a comprehensive description and discussion of these frontier topics for interlayer excitons in TMD vdW heterostructures to provide valuable guidance for researchers in this field.
基金support from the Naional Natural Science Foundation of China(Grant No.61775241)Hunan province key research and development project(Grant No.2019GK2233)+5 种基金Hunan Provincial Science Fund for Distinguished Young Scholars(Grant No.2020JJ2059)the Youth Innovaticn Team(Grant No.2019012)of CSU,the Science and Technolgy Innovaton Basic Research Project of Shenzhen(Grant No.JCY120190806144418859)the National Natural Science Foundation of China (Nos.62090035,U19A2090)the Key Program of Science and Technology Department of Hunan Province(2019XK2001,2020XK2001)support of the High-Performance Complex Manufacturing Key State Lab Project,Central South University(Grant No.ZZYJKT2020-12)ZWL.thanks the support from the Australian Research Council(ARC Discovery Project,DP180102976).
文摘Recent advances in twisted van der Waals heterostructure superlattices have emerged as a powerful and attractive platform for exploring novel condensed matter physics due to the interplay between the moirépotential and Coulomb interactions.The moirésuperlattices act as a periodic confinement potential in space to capture interlayer excitons(IXs),resulting in moiréexciton arrays,which provide opportunities for quantum emitters and many-body physics.The observation of moiréIXs in twisted transition-metal dichalcogenide(TMD)heterostructures has recently been widely reported.However,the capture and study of the moiréintralayer excitons based on TMD twisted homobilayer(T-HB)remain elusive.Here,we report the observation of moiréintralayer excitons in a WSe_(2)/WSe_(2) T-HB with a small twist angle by measuring PL spectrum.The multiple split peaks with an energy range of 1.55-1.73 eV are different from that of the monolayer WSe_(2) exciton peaks.The split peaks were caused by the trapping of intralayer excitons via the moirépotential.The confinement effect of the moirépotential on the moiréintralayer excitons was further demonstrated by the changing of temperature,laser power,and valley polarization.Our findings provide a new avenue for exploring new correlated quantum phenomena and their applications.
基金financially supported by the National Natural Science Foundation of China (51525202, 61635001, 52072117 and 21703059)the Key Program of the Hunan Provincial Science and Technology Department (2019XK2001)the International Science and Technology Innovation Cooperation Base of Hunan Province (2018WK4004)
文摘Substitutional doping of two-dimensional(2D)transition metal dichalcogenides(TMDs)has been recognized as a promising strategy to tune their optoelectronic properties for a wide array of applications.However,controllable doping of TMDs remains a challenging issue due to the natural doping of these materials.Here,we demonstrate the controllable growth of indium-doped p-type WS_(2) monolayers with various doping concentrations via chemical vapor deposition(CVD)of a host tungsten(W)source and indium(In)dopant.Scanning transmission electron microscopy confirmed that In atoms successfully substitute the W atoms in the WS_(2) lattice.Intriguingly,the photoluminescence of the doped sample experiences strong intensity modulation by the doping concentration,which first increases remarkably with an enhancement factor up to~35 and then decreases gradually when further increasing the doping concentration.Such a phenomenon is attributed to the progressive change of the exciton to trion ratio as well as the defect concentration in the doped samples.The assignment was further verified by the electric behavior of the fabricated In-doped WS_(2) field effect transistors,which changes regularly from n-type to bipolar and finally to p-type behavior with increasing doping concentration.The successful growth of p-type monolayer WS_(2) and the dual control of its optical and electrical properties by In doping may provide a promising method to engineer the opto-electronic properties of 2D materials.
基金supported by the National Natural Science Foundation of China(62175061,52172140,52221001,and 52072117)the Natural Science Foundation of Hunan Province(2022JJ30167)+1 种基金the Outstanding Scholarship Program of Hunan Province(2021JJ10021)China Postdoctoral Science Foundation(BX20220104,2022M720046 and 2022TQ0100)。
基金financially supported by the National Natural Science Foundation of China(52002125,U19A2090,62090035,51972105,61905071,and 52172140)China Postdoctoral Science Foundation(2020M672479 and 2020M680112)+4 种基金the Natural Science Foundation of Hunan Province(2021JJ40102 and 2021JJ30132)the Key Program of Science and Technology Department of Hunan Province(2019XK2001 and2020XK2001)the Science and Technology Innovation Program of Hunan Province(2020RC2028)the International Science and Technology Innovation Cooperation Base of Hunan Province(2018WK404)the Open Project Program of Wuhan National Laboratory for Optoelectronics(2020WNLOKF002)。
文摘The optoelectronic properties of atomically thin transition metal dichalcogenides(TMDs)are largely influenced by defect populations(DPs).In this work,we fabricate WSmonolayers with different DPs by varying the fabrication methods and further reveal their distinct exciton-exciton interactions.Steady-state photoluminescence(PL)experiments show that the monolayer with the lowest DP shows optimal PL intensity at low excitation power;however,it is overtaken and significantly surpassed by monolayers with higher DPs at high excitation powers.Excitation-power-dependent experiments demonstrate that these monolayers exhibit distinct PL saturation behaviors with the threshold power differing by four orders of magnitude.Combined with in situ PL imaging and time-resolved PL experiments,we attribute such PL evolution discrepancies to the different DPs within these monolayers,which largely influence the exciton diffusion behavior and subsequently bring about distinct nonradiative exciton-exciton annihilations(EEAs).Valley polarization experiments are further employed to re-examine the DPs of these monolayers.This work reveals the distinct PL behaviors and underlying exciton dynamics in TMD monolayers with different DPs,which can largely facilitate the engineering of relevant high-performance devices for practical applications.
基金supported by the National Natural Science Foundation of China(Nos.52221001,U19A2090,62090035,52172140,51902098,62175061)the Key Program of the Hunan Provincial Science and Technology Department(Nos.2019XK2001,2020XK2001)+3 种基金the International Science and Technology Innovation Cooperation Base of Hunan Province(No.2018WK4004)the Outstanding Scholarship Program of Hunan Province(No.2021JJ10021)the Science and Technology Innovation Program of Hunan Province(No.2021RC3061)the Natural Science Foundation of Hunan Province(Nos.2022JJ30167,2021JJ20016).
文摘With the unprecedented increasing demand for extremely fast processing speed and huge data capacity,traditional silicon-based information technology is becoming saturated due to the encountered bottle-necks of Moore's Law.New material systems and new device architectures are considered promising strategies for this challenge.Two-dimensional(2D)materials are layered materials and garnered persistent attention in recent years owing to their advantages in ultrathin body,strong light-matter interaction,flexible integration,and ultrabroad operation wavelength range.To this end,the integra-tion of 2D materials into silicon-based platforms opens a new path for silicon photonic integration.In this work,a comprehensive review is given of the recent signs of progress related to 2D material inte-grated optoelectronic devices and their potential applications in silicon photonics.Firstly,the basic op-tical properties of 2D materials and heterostructures are summarized in the first part.Then,the state-of-the-art three typical 2D optoelectronic devices for silicon photonic applications are reviewed in detail.Finally,the perspective and challenges for the aim of 3D monolithic heterogeneous integration of these 2D optoelectronic devices are discussed.
基金the National Natural Science Foundation of China(Grant Nos.62090035,U19A2090,and 61905071)the Key Program of the Hunan Provincial Science and Technology Department(Nos.2019XK2001 and 2020XK2001)the International Science and Technology Innovation Cooperation Base of Hunan Province(No.2018WK4004).
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDs)have attracted extensive attention due to their unique electronic and optical properties.In particular,TMDs can be fexibly combined to form diverse vertical van der Waals(vdWs)heterostructures without the limitation of lattice matching,which creates vast opportunities for fundamental investigation of novel optoelectronic applications.Here,we report an atomically thin vertical p-n junction WSe_(2)/MoS_(2)produced by a chemical vapor deposition method.Transmission electron microscopy and steady-state photoluminescence experiments reveal its high quality and excellent optical properties.Back gate feld efect transistor(FET)constructed using this p-n junction exhibits bipolar behaviors and a mobility of 9 cm^(2)/(V·s).In addition,the photodetector based on MoS_(2)/WSe_(2)heterostructures displays outstanding optoelectronic properties(R=8 A/W,D^(*)=2.93×10^(11)Jones,on/of ratio of 10^(4)),which benefted from the built-in electric feld across the interface.The direct growth of TMDs p-n vertical heterostructures may ofer a novel platform for future optoelectronic applications.
