The continuous downscaling(sub 5-nm nodes) of the processing technology is severely hampered by the shortchannel effects of the silicon(Si) material, which degrade the transistor's performance and raise the demand...The continuous downscaling(sub 5-nm nodes) of the processing technology is severely hampered by the shortchannel effects of the silicon(Si) material, which degrade the transistor's performance and raise the demand in the development of new device structures and materials to overcome them. Two-dimensional(2D) semiconductors are promising candidates for next-generation electronic materials owing to their atomic thickness and van der Waals(vdW) surface.展开更多
Achieving strong coupling between plasmonic oscillators can significantly modulate their intrinsic optical properties.Here,we report the direct observation of ultrafast plasmonic hot electron transfer from an Au grati...Achieving strong coupling between plasmonic oscillators can significantly modulate their intrinsic optical properties.Here,we report the direct observation of ultrafast plasmonic hot electron transfer from an Au grating array to an MoS_(2) monolayer in the strong coupling regime between localized surface plasmons(LSPs)and surface plasmon polaritons(SPPs).By means of femtosecond pump-probe spectroscopy,the measured hot electron transfer time is approximately 40 fs with a maximum external quantum yield of 1.65%.Our results suggest that strong coupling between LSPs and SPPs has synergetic effects on the generation of plasmonic hot carriers,where SPPs with a unique nonradiative feature can act as an‘energy recycle bin’to reuse the radiative energy of LSPs and contribute to hot carrier generation.Coherent energy exchange between plasmonic modes in the strong coupling regime can further enhance the vertical electric field and promote the transfer of hot electrons between the Au grating and the MoS_(2) monolayer.Our proposed plasmonic strong coupling configuration overcomes the challenge associated with utilizing hot carriers and is instructive in terms of improving the performance of plasmonic opto-electronic devices.展开更多
Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom...Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom, including real spin, valley pseudospin, and layer pseudospin. For example, spin-valley coupling results in valley-dependent circular dichroism in which electrons with particular spin （up or down） can be selectively excited by chiral optical pumping in monolayer TMDs, whereas in few-layer TMDs, the interlayer hopping further affects the spin-valley coupling. In addition to valley and layer pseudospins, here we propose a new degree of freedom--stacking pseudospin--and demonstrate new phenomena correlated to this new stacking freedom that otherwise require the application of external electrical or magnetic field. We investigated all possible stacking configurations of chemical-vapor-deposition-grown trilayer MoS2 （AAA, ABB, AAB, ABA, and 3R）. Although the AAA, ABA, 3R stackings possess a sole peak with lower degree of valley polarization than that in monolayer samples, the AAB （ABB） stackings exhibit two distinct peaks, one similar to that observed in monolayer MoS2 and findings provide a more future valleytronics. an additional unpolarized complete understanding of peak at lower energy. Our valley quantum control for展开更多
Our theoretical findings demonstrate for the first time a possibility of band-gap engineering of monolayer MoS2 crystals by oxygen and the presence of vacancies. Oxygen atoms are revealed to substitute sulfur ones, fo...Our theoretical findings demonstrate for the first time a possibility of band-gap engineering of monolayer MoS2 crystals by oxygen and the presence of vacancies. Oxygen atoms are revealed to substitute sulfur ones, forming stable MoS2-xOx ternary compounds, or adsorb on top of the sulfur atoms. The substituting oxygen provides a decrease of the band gap from 1.86 to 1.64 eV and transforms the material from a direct-gap to an indirect-gap semiconductor. The surface adsorbed oxygen atoms decrease the band gap up to 0.98 eV depending on their location tending to the metallic character of the electron energy bands at a high concentration of the adsorbed atoms. Oxygen plasma processing is proposed as an effective technology for such band-gap modifications.展开更多
基金financially supported by the National Natural Science Foundation of China(61674050,62004056,and 61874158)the Project of Distinguished Young of Hebei Province(A2018201231)+7 种基金the Support Program for the Top Young Talents of Hebei Province(70280011807)the Hundred Persons Plan of Hebei Province(E2018050004 and E2018050003)the Supporting Plan for 100 Excellent Innovative Talents in Colleges and Universities of Hebei Province(SLRC2019018)the Special Project of Strategic Leading Science and Technology of Chinese Academy of Sciences(XDB44000000-7)the Special Support Funds for National High Level Talents(041500120001)Hebei Basic Research Special Key Project(F2021201045)the Science and Technology Project of Hebei Education Department(QN2020178 and QN2021026)Singapore Ministry of Education(Ac RF TIER 2-MOE2019-T2-2-075)。
文摘The continuous downscaling(sub 5-nm nodes) of the processing technology is severely hampered by the shortchannel effects of the silicon(Si) material, which degrade the transistor's performance and raise the demand in the development of new device structures and materials to overcome them. Two-dimensional(2D) semiconductors are promising candidates for next-generation electronic materials owing to their atomic thickness and van der Waals(vdW) surface.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFA0205700)National Basic Research Program of China(Grant Nos.2015CB932403,2017YFA0206000)+4 种基金National Science Foundation of China(Grant Nos.11674012,61422501,11374023,61521004 and 21790364)Beijing Natural Science Foundation(Grant No.L140007)Foundation for the Author of National Excellent Doctoral Dissertation of PR China(Grant No.201420)National Program for Support of Top-notch Young Professionals(Grant No.W02070003)Ministry of Education Singapore under Grant No.MOE2015-T2-2-043.
文摘Achieving strong coupling between plasmonic oscillators can significantly modulate their intrinsic optical properties.Here,we report the direct observation of ultrafast plasmonic hot electron transfer from an Au grating array to an MoS_(2) monolayer in the strong coupling regime between localized surface plasmons(LSPs)and surface plasmon polaritons(SPPs).By means of femtosecond pump-probe spectroscopy,the measured hot electron transfer time is approximately 40 fs with a maximum external quantum yield of 1.65%.Our results suggest that strong coupling between LSPs and SPPs has synergetic effects on the generation of plasmonic hot carriers,where SPPs with a unique nonradiative feature can act as an‘energy recycle bin’to reuse the radiative energy of LSPs and contribute to hot carrier generation.Coherent energy exchange between plasmonic modes in the strong coupling regime can further enhance the vertical electric field and promote the transfer of hot electrons between the Au grating and the MoS_(2) monolayer.Our proposed plasmonic strong coupling configuration overcomes the challenge associated with utilizing hot carriers and is instructive in terms of improving the performance of plasmonic opto-electronic devices.
文摘Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom, including real spin, valley pseudospin, and layer pseudospin. For example, spin-valley coupling results in valley-dependent circular dichroism in which electrons with particular spin （up or down） can be selectively excited by chiral optical pumping in monolayer TMDs, whereas in few-layer TMDs, the interlayer hopping further affects the spin-valley coupling. In addition to valley and layer pseudospins, here we propose a new degree of freedom--stacking pseudospin--and demonstrate new phenomena correlated to this new stacking freedom that otherwise require the application of external electrical or magnetic field. We investigated all possible stacking configurations of chemical-vapor-deposition-grown trilayer MoS2 （AAA, ABB, AAB, ABA, and 3R）. Although the AAA, ABA, 3R stackings possess a sole peak with lower degree of valley polarization than that in monolayer samples, the AAB （ABB） stackings exhibit two distinct peaks, one similar to that observed in monolayer MoS2 and findings provide a more future valleytronics. an additional unpolarized complete understanding of peak at lower energy. Our valley quantum control for
基金supported by the Joint BRFFR-CNRS Project (No. F15F-003)the Visby Program: scholarships for PhD studies and postdoctoral research in Sweden
文摘Our theoretical findings demonstrate for the first time a possibility of band-gap engineering of monolayer MoS2 crystals by oxygen and the presence of vacancies. Oxygen atoms are revealed to substitute sulfur ones, forming stable MoS2-xOx ternary compounds, or adsorb on top of the sulfur atoms. The substituting oxygen provides a decrease of the band gap from 1.86 to 1.64 eV and transforms the material from a direct-gap to an indirect-gap semiconductor. The surface adsorbed oxygen atoms decrease the band gap up to 0.98 eV depending on their location tending to the metallic character of the electron energy bands at a high concentration of the adsorbed atoms. Oxygen plasma processing is proposed as an effective technology for such band-gap modifications.
