Stacking of atomically thin layers of two-dimensional materials has revealed extraordinary physical phenomena owing to van der Waals(vdW)interaction at the interface.However,most of the studies focused on the transiti...Stacking of atomically thin layers of two-dimensional materials has revealed extraordinary physical phenomena owing to van der Waals(vdW)interaction at the interface.However,most of the studies focused on the transition metal dichalcogenide(TMD)/TMD heterostructure,while the interlayer coupling of the TMD/hexagonal boron nitride(h-BN)heterostructure has not been extensively explored despite its importance.In this study,the temperature-dependent interlayer coupling is demonstrated in a heterostructure of molybdenum disulfide(MoS2)and h-BN.The interface between MoS2 and the insulating substrate exerts a significant spectroscopic impact on MoS2 through substrate-induced local strain,charged impurity,and vdW interactions.Under non-resonant conditions,temperature-dependent peak shifts in Raman and photoluminescence(PL)spectra of MoS2 reveal the evolution of interlayer coupling.Phonon frequencies and PL peak energies at different temperatures demonstrate how substrate-induced strain,impurity,and vdW interactions at the interface influence phonon vibration and excitonic transition of MoS2.Under resonant conditions at low temperature,anomalous Raman modes appear in the MoS2/h-BN heterostructure because of the enhanced electron-phonon coupling and vdW interactions.The anomalous Raman modes are quantitatively investigated by the deconvolution of the resonance Raman spectra and described by interlayer coupling at low temperature,in agreement with complementary indications from the temperature-dependent evolution of non-resonant Raman and PL spectra.展开更多
Two-dimensional(2D)materials have recently provided a new perspective on optoelectronics because of their unique layered structure and excellent physical properties.However,their potential use as optoelectric devices ...Two-dimensional(2D)materials have recently provided a new perspective on optoelectronics because of their unique layered structure and excellent physical properties.However,their potential use as optoelectric devices has been limited by the trade-off between photoresponsivity and response time.Here,based on a vertically stacked atomically thin p-n junction,we propose a gap-mode plasmon structure that simultaneously enables enhanced responsivity and rapid photodetection.The atomically thin 2D materials act as a spacer for enhancing the gap-mode plasmons,and their short transit length in the vertical direction allows fast photocarrier transport.We demonstrate a high responsivity of up to 8.67 A/W with a high operation speed that exceeds 35 MHz under a 30 nW laser power.Spectral photocurrent,absorption,and a numerical simulation are used to verify the effectiveness of the gap-mode plasmons in the device.We believe that the design strategy proposed in this study can pave the way for a platform to overcome the trade-off between responsivity and response time.展开更多
基金This work was supported by the Creative Materials Discovery Program(No.2016M3D1A1900035)the Basic Research Program(No.2019R1A2C2009171)through the National Research Foundation(NRF)funded by the Ministry of Science and ICT,Republic of Korea.
文摘Stacking of atomically thin layers of two-dimensional materials has revealed extraordinary physical phenomena owing to van der Waals(vdW)interaction at the interface.However,most of the studies focused on the transition metal dichalcogenide(TMD)/TMD heterostructure,while the interlayer coupling of the TMD/hexagonal boron nitride(h-BN)heterostructure has not been extensively explored despite its importance.In this study,the temperature-dependent interlayer coupling is demonstrated in a heterostructure of molybdenum disulfide(MoS2)and h-BN.The interface between MoS2 and the insulating substrate exerts a significant spectroscopic impact on MoS2 through substrate-induced local strain,charged impurity,and vdW interactions.Under non-resonant conditions,temperature-dependent peak shifts in Raman and photoluminescence(PL)spectra of MoS2 reveal the evolution of interlayer coupling.Phonon frequencies and PL peak energies at different temperatures demonstrate how substrate-induced strain,impurity,and vdW interactions at the interface influence phonon vibration and excitonic transition of MoS2.Under resonant conditions at low temperature,anomalous Raman modes appear in the MoS2/h-BN heterostructure because of the enhanced electron-phonon coupling and vdW interactions.The anomalous Raman modes are quantitatively investigated by the deconvolution of the resonance Raman spectra and described by interlayer coupling at low temperature,in agreement with complementary indications from the temperature-dependent evolution of non-resonant Raman and PL spectra.
基金This work was supported by the National Research Foundation of Korea(NRF)through Basic Research Program(No.2019R1A2C2009171)Creative Materials Discovery Program(No.2016M3D1A1900035).
文摘Two-dimensional(2D)materials have recently provided a new perspective on optoelectronics because of their unique layered structure and excellent physical properties.However,their potential use as optoelectric devices has been limited by the trade-off between photoresponsivity and response time.Here,based on a vertically stacked atomically thin p-n junction,we propose a gap-mode plasmon structure that simultaneously enables enhanced responsivity and rapid photodetection.The atomically thin 2D materials act as a spacer for enhancing the gap-mode plasmons,and their short transit length in the vertical direction allows fast photocarrier transport.We demonstrate a high responsivity of up to 8.67 A/W with a high operation speed that exceeds 35 MHz under a 30 nW laser power.Spectral photocurrent,absorption,and a numerical simulation are used to verify the effectiveness of the gap-mode plasmons in the device.We believe that the design strategy proposed in this study can pave the way for a platform to overcome the trade-off between responsivity and response time.
