Graphene with linear energy dispersion and weak electron-phonon interaction is highly anticipated to harvest hot electrons in a broad wavelength range.However,the limited absorption and serious backscattering of hot-e...Graphene with linear energy dispersion and weak electron-phonon interaction is highly anticipated to harvest hot electrons in a broad wavelength range.However,the limited absorption and serious backscattering of hot-electrons result in inadequate quantum yields,especially in the mid-infrared range.Here,we report a macroscopic assembled graphene(nMAG)nanofilm/silicon heterojunction for ultrafast mid-infrared photodetection.The assembled Schottky diode works in 1.5-4.0μm at room temperature with fast response(20-30 ns,rising time,4 mm2 window)and high detectivity(1.61011 to 1.9109 Jones from 1.5 to 4.0μm)under the pulsed laser,outperforming single-layer-graphene/silicon photodetectors by 2-8 orders.These performances are attributed to the greatly enhanced photo-thermionic effect of electrons in nMAG due to its high light absorption(~40%),long carrier relaxation time(~20 ps),low work function(4.52 eV),and suppressed carrier number fluctuation.The nMAG provides a long-range platform to understand the hot-carrier dynamics in bulk 2D materials,leading to broadband and ultrafast MIR active imaging devices at room temperature.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:52090030,51973191,92164106,61874094China Postdoctoral Science Foundation,Grant/Award Number:2020M681819+2 种基金Fundamental Research Funds for the Central Universities,Grant/Award Numbers:K20200060,2021FZZX001-17Key Laboratory of Novel Adsorption and Separation Materials and Application Technology of Zhejiang Province,Grant/Award Number:512301-I21502Hundred Talents Program of Zhejiang University,Grant/Award Number:188020*194231701/113。
文摘Graphene with linear energy dispersion and weak electron-phonon interaction is highly anticipated to harvest hot electrons in a broad wavelength range.However,the limited absorption and serious backscattering of hot-electrons result in inadequate quantum yields,especially in the mid-infrared range.Here,we report a macroscopic assembled graphene(nMAG)nanofilm/silicon heterojunction for ultrafast mid-infrared photodetection.The assembled Schottky diode works in 1.5-4.0μm at room temperature with fast response(20-30 ns,rising time,4 mm2 window)and high detectivity(1.61011 to 1.9109 Jones from 1.5 to 4.0μm)under the pulsed laser,outperforming single-layer-graphene/silicon photodetectors by 2-8 orders.These performances are attributed to the greatly enhanced photo-thermionic effect of electrons in nMAG due to its high light absorption(~40%),long carrier relaxation time(~20 ps),low work function(4.52 eV),and suppressed carrier number fluctuation.The nMAG provides a long-range platform to understand the hot-carrier dynamics in bulk 2D materials,leading to broadband and ultrafast MIR active imaging devices at room temperature.
