Near-field imaging provides insight into the fundamental light-matter interactions on a nanometer scale.Scattering-type scanning near-field optical microscopy(s-SNOM)is a powerful technique capable of overcoming the d...Near-field imaging provides insight into the fundamental light-matter interactions on a nanometer scale.Scattering-type scanning near-field optical microscopy(s-SNOM)is a powerful technique capable of overcoming the diffraction limit and achieving spatial resolutions below 10 nm(sub-10 nm).However,constrained by the working mechanisms,the signal-to-noise ratio of the imaging is highly affected by undesired background scattering light,which is found to be associated with the optical mode and excitation wavelength,especially for samples with a large specific surface area.Here,we propose a high-resolution method with high-order near-field modes at the infrared range to measure low-dimensional materials.With this technique,we reveal the excitation and propagation of the surface plasmon polaritons in graphene and carbon nanotubes,which was impossible with the low-order imaging approach.Besides,the imaging quality for gold nanoparticles on gold thin film is much better than the AFM results.This paper offers an advanced approach for high-resolution measurement of low-dimensional materials with s-SNOM,owning great potential for sensitive nanoscale imaging.展开更多
Flexible photodetectors with wavelength-selective response are essential for next-generation wearable and biointegrated optoelectronics.However,conventional devices typically rely on external filters or complex struct...Flexible photodetectors with wavelength-selective response are essential for next-generation wearable and biointegrated optoelectronics.However,conventional devices typically rely on external filters or complex structures,limiting the flexibility,integration,and broadband applications.Here,we present a gate-tunable flexible photodetector based on asymmetric van der Waals heterostructures composed of graphene,Molybdenum disulfide and singlewalled carbon nanotubes.The asymmetric design induces a built-in electric field,effectively suppressing dark current and enabling dynamic modulation of spectral responsivity via gate voltage.As a result,the device achieves switchable photoresponse peaks at 450 nm and 635 nm,demonstrating a high responsivity of up to 40.3 A/W and a specific detectivity of 1.3×10^(11)Jones.Furthermore,the device maintains robust performance under mechanical deformation and gate voltages.This work offers a scalable approach to realize intrinsically wavelength-selective,high-performance photodetectors on flexible substrates,providing new opportunities for integrated,broadband,and flexible optoelectronic applications.展开更多
With the development of imaging and measurement technologies,scanning near-field optical microscopy(SNOM)has achieved high signal-to-noise ratio.The resolution of a fibre probe-based SNOM system is capable of reaching...With the development of imaging and measurement technologies,scanning near-field optical microscopy(SNOM)has achieved high signal-to-noise ratio.The resolution of a fibre probe-based SNOM system is capable of reaching 10 nm.However,SNOM applications are presently constrained to the measurement of near-field optical information to relatively straightforward structures,including quantum dots,carbon nanotubes,graphene,and so forth.The geometry of conventional fibre probes,with tips at an angle of 30°-60°,presents a challenge for accurately imaging complex surface structures.This paper proposes a carbon nanotube composite fibre probe(CNT-FP)with a large aspect ratio.The key point is that a carbon nanotube bundle is composited at the tip of conventional surface plasmon polaritons fibre probes(SPPs-FP),which are the fibre probes coated with gold film to excite the SPPs.The coupling,propagation,and focusing effects of SPPs on the carbon nanotube bundle are verified.CNT-FPs have been fabricated and applied to measure a grating with the depth of 400 nm and the width of 400 nm.The experimental results show that the measurement accuracy and imaging quality of CNT-FP are nearly one order of magnitude higher than that of conventional SPPs-FP,as evidenced by evaluation criteria such as line roughness and volatility index.Moreover,it achieves an optical resolution of 72.1 nm in the measurements of a nano structure with large aspect ratio.It provides an effective solution of measuring structures with larger aspect ratios.展开更多
Graphene/silicon Schottky junctions have been proven efficient for photodetection,but the existing high dark current seriously restricts applications such as weak signal detection.In this paper,a thin layer of gadolin...Graphene/silicon Schottky junctions have been proven efficient for photodetection,but the existing high dark current seriously restricts applications such as weak signal detection.In this paper,a thin layer of gadolinium iron garnet(Gd3Fe5O12,GdIG)film is introduced to engineer the interface of a graphene/silicon Schottky photodetector.The novel structure shows a significant decrease in dark current by 54 times at a-2 V bias.It also exhibits high performance in a self-powered mode in terms of an Ilight/Idark ratio up to 8.2×10^(6)and a specific detectivity of 1.35×10^(13)Jones at 633 nm,showing appealing potential for weak-light detection.Practical suitability characterizations reveal a broadband absorption covering ultraviolet to near-infrared light and a large linear response with a wide range of light intensities.The device holds an operation speed of 0.15 ms,a stable response for 500 continuous working cycles,and long-term environmental stability after several months.Theoretical analysis shows that the interlayer increases the barrier height and passivates the contact surface so that the dark current is suppressed.This work demonstrates the good capacity of GdIG thin films as interlayer materials and provides a new solution for high-performance photodetectors.展开更多
The difficulty of obtaining high-intensity localized light spots for optical probes leads to their lack of good applications in nanoimaging.Here we demonstrate a Fabry–Pérot resonance flat-based plasmonic fiber prob...The difficulty of obtaining high-intensity localized light spots for optical probes leads to their lack of good applications in nanoimaging.Here we demonstrate a Fabry–Pérot resonance flat-based plasmonic fiber probe(FPFP).The simulation results show that the probe can obtain a nanofocusing spot at the tip with the radially polarized mode.The Fabry–Pérot interference structure is used to control the plasmon propagation on the surface of the probe,it effectively improves the local spot intensity at the tip.Furthermore,the experimental results verify that the FPFP(tip curvature radius is 20 nm)prepared by chemical etching method can obtain a nanofocusing spot at the tip.The nanoimaging of the gold slit structure demonstrates the nanoimaging capability of the FPFP,the 36.9 nm slit width is clearly identified by the FPFP.展开更多
Flexible photodetectors are fundamental components for developing wearable systems,which can be widely used for medical detection,environmental monitoring and flexible imaging.However,compared with 3D materials,lowdim...Flexible photodetectors are fundamental components for developing wearable systems,which can be widely used for medical detection,environmental monitoring and flexible imaging.However,compared with 3D materials,lowdimensional materials have degraded performance,a key challenge for current flexible photodetectors.Here,a highperformance broadband photodetector has been proposed and fabricated.By combining the high mobility of graphene(Gr)with the strong light–matter interactions of single-walled carbon nanotubes(SWCNTs)and molybdenum disulfide(MoS2),the flexible photodetector exhibits a greatly improved photoresponse covering the visible to near-infrared range.Additionally,a thin layer of gadolinium iron garnet(Gd_(3)Fe_(5)O_(12),GdlG)film is introduced to improve the interface of the double van der Waals heterojunctions to reduce the dark current.The SWCNT/GdIG/Gr/GdIG/MoS2 flexible photodetector exhibits a high photoresponsivity of 47.375 A/W and a high detectivity of 1.952×1012 Jones at 450 nm,a high photoresponsivity of 109.311 A/W and a high detectivity of 4.504×10^(12) Jones at 1080 nm,and good mechanical stability at room temperature.This work demonstrates the good capacity of GdIGassisted double van der Waals heterojunctions on flexible substrates and provides a new solution for constructing high-performance flexible photodetectors.展开更多
In this work,the electrical property of Au/graphene oxide/p-InP hetero-structure has been evaluated by 1-V and C-V measure-ments in dark and iluminated conditions(visible light).The diode exhibited significant rectify...In this work,the electrical property of Au/graphene oxide/p-InP hetero-structure has been evaluated by 1-V and C-V measure-ments in dark and iluminated conditions(visible light).The diode exhibited significant rectifying behavior,thus indicating the heterojunction-lype diode.The key electrical parameters of heterojunction diode including ideality factor(n),series resistance(R),shunt resistance(Rsh),and barrier height(Фb)are estimated from I-V data based on the theory of thermionic emission.The modifed Norde and Cheung's methods were utilized to evaluate the electrical parameters and compared the results.The current conduction mechanism at different voltage regions of I-V has also been investigated.The variation of 1/C versus voltage signifies linearity at high frequency(1 MHz),indicating that the type of heterojunction can be abrupt.The experimental outcomes of this study revealed that the performance of heterojunction diode in dark is considerably good as compared to the ilumination condition with respect to the lower values of Фp,n,R,and interface state density(Nss).展开更多
Delivering light to the nanoscale using a flexible and easily integrated fiber platform holds potential in various fields of quantum science and bioscience.However,rigorous optical alignment,sophisticated fabrication ...Delivering light to the nanoscale using a flexible and easily integrated fiber platform holds potential in various fields of quantum science and bioscience.However,rigorous optical alignment,sophisticated fabrication process,and low spatial resolution of the fiber-based nanoconcentrators limit the practical applications.Here,a broadband azimuthal plasmon interference nanofocusing technique on a fiber-coupled spiral tip is demonstrated for fiber-based near-field optical nanoimaging.The spiral plasmonic fiber tip fabricated through a robust and reproducible process can reverse the polarization and modulate the mode field of the surface plasmon polaritons in three-dimensionally azimuthal direction,resulting in polarization-insensitive,broad-bandwidth,and azimuthal interference nanofocusing.By integrating this with a basic scanning near-field optical microscopy,a high optical resolution of 31 nm and beyond is realized.The high performance and the easy incorporation with various existing measurement platforms offered by this fiber-based nanofocusing technique have great potential in near-field optics,tip-enhanced Raman spectroscopy,nonlinear spectroscopy,and quantum sensing.展开更多
Photodetectors(PDs)play a crucial role in imaging,sensing,communication systems,etc.Graphene(Gr),a leading two-dimensional material,has demonstrated significant potential for photodetection in recent years.However,its...Photodetectors(PDs)play a crucial role in imaging,sensing,communication systems,etc.Graphene(Gr),a leading two-dimensional material,has demonstrated significant potential for photodetection in recent years.However,its relatively weak interaction with light poses challenges for practical applications.The integration of silicon(Si)and perovskite quantum dots(PQDs)has opened new avenues for Gr in the realm of next-generation optoelectronics.This review provides a comprehensive investigation of Gr/Si Schottky junction PDs and Gr/PQD hybrid PDs as well as their heterostructures.The operating principles,design,fabrication,optimization strategies,and typical applications of these devices are studied and summarized.Through these discussions,we aim to illuminate the current challenges and offer insights into future directions in this rapidly evolving field.展开更多
基金supported by the China National Funds for Distinguished Young Scientists(No.52225507)the Key Research and Development Program of Shaanxi Province(2024PT-ZCK-40)+1 种基金National Natural Science Foundation of China(52305584)the Fundamental Research Funds for the Central Universities.
文摘Near-field imaging provides insight into the fundamental light-matter interactions on a nanometer scale.Scattering-type scanning near-field optical microscopy(s-SNOM)is a powerful technique capable of overcoming the diffraction limit and achieving spatial resolutions below 10 nm(sub-10 nm).However,constrained by the working mechanisms,the signal-to-noise ratio of the imaging is highly affected by undesired background scattering light,which is found to be associated with the optical mode and excitation wavelength,especially for samples with a large specific surface area.Here,we propose a high-resolution method with high-order near-field modes at the infrared range to measure low-dimensional materials.With this technique,we reveal the excitation and propagation of the surface plasmon polaritons in graphene and carbon nanotubes,which was impossible with the low-order imaging approach.Besides,the imaging quality for gold nanoparticles on gold thin film is much better than the AFM results.This paper offers an advanced approach for high-resolution measurement of low-dimensional materials with s-SNOM,owning great potential for sensitive nanoscale imaging.
基金supported by the China National Funds for Distinguished Young Scientists(No.52225507)the Key Research and Development Program of Shaanxi Province(2024PT-ZCK-40)the Fundamental Research Funds for the Central Universities.
文摘Flexible photodetectors with wavelength-selective response are essential for next-generation wearable and biointegrated optoelectronics.However,conventional devices typically rely on external filters or complex structures,limiting the flexibility,integration,and broadband applications.Here,we present a gate-tunable flexible photodetector based on asymmetric van der Waals heterostructures composed of graphene,Molybdenum disulfide and singlewalled carbon nanotubes.The asymmetric design induces a built-in electric field,effectively suppressing dark current and enabling dynamic modulation of spectral responsivity via gate voltage.As a result,the device achieves switchable photoresponse peaks at 450 nm and 635 nm,demonstrating a high responsivity of up to 40.3 A/W and a specific detectivity of 1.3×10^(11)Jones.Furthermore,the device maintains robust performance under mechanical deformation and gate voltages.This work offers a scalable approach to realize intrinsically wavelength-selective,high-performance photodetectors on flexible substrates,providing new opportunities for integrated,broadband,and flexible optoelectronic applications.
基金support by the National Science Fund for Outstanding Young Scholars(No.52225507).
文摘With the development of imaging and measurement technologies,scanning near-field optical microscopy(SNOM)has achieved high signal-to-noise ratio.The resolution of a fibre probe-based SNOM system is capable of reaching 10 nm.However,SNOM applications are presently constrained to the measurement of near-field optical information to relatively straightforward structures,including quantum dots,carbon nanotubes,graphene,and so forth.The geometry of conventional fibre probes,with tips at an angle of 30°-60°,presents a challenge for accurately imaging complex surface structures.This paper proposes a carbon nanotube composite fibre probe(CNT-FP)with a large aspect ratio.The key point is that a carbon nanotube bundle is composited at the tip of conventional surface plasmon polaritons fibre probes(SPPs-FP),which are the fibre probes coated with gold film to excite the SPPs.The coupling,propagation,and focusing effects of SPPs on the carbon nanotube bundle are verified.CNT-FPs have been fabricated and applied to measure a grating with the depth of 400 nm and the width of 400 nm.The experimental results show that the measurement accuracy and imaging quality of CNT-FP are nearly one order of magnitude higher than that of conventional SPPs-FP,as evidenced by evaluation criteria such as line roughness and volatility index.Moreover,it achieves an optical resolution of 72.1 nm in the measurements of a nano structure with large aspect ratio.It provides an effective solution of measuring structures with larger aspect ratios.
基金We would like to thank the Program for Science and Technology Innovation Group of Shaanxi Province(2019TD-011)the Key Research and Development Program of Shaanxi Province(2020ZDLGY04-02)the Fundamental Research Funds for the Central Universities for their support.
文摘Graphene/silicon Schottky junctions have been proven efficient for photodetection,but the existing high dark current seriously restricts applications such as weak signal detection.In this paper,a thin layer of gadolinium iron garnet(Gd3Fe5O12,GdIG)film is introduced to engineer the interface of a graphene/silicon Schottky photodetector.The novel structure shows a significant decrease in dark current by 54 times at a-2 V bias.It also exhibits high performance in a self-powered mode in terms of an Ilight/Idark ratio up to 8.2×10^(6)and a specific detectivity of 1.35×10^(13)Jones at 633 nm,showing appealing potential for weak-light detection.Practical suitability characterizations reveal a broadband absorption covering ultraviolet to near-infrared light and a large linear response with a wide range of light intensities.The device holds an operation speed of 0.15 ms,a stable response for 500 continuous working cycles,and long-term environmental stability after several months.Theoretical analysis shows that the interlayer increases the barrier height and passivates the contact surface so that the dark current is suppressed.This work demonstrates the good capacity of GdIG thin films as interlayer materials and provides a new solution for high-performance photodetectors.
基金the National Science Fund for Distinguished Young Scholars(No.52225507).
文摘The difficulty of obtaining high-intensity localized light spots for optical probes leads to their lack of good applications in nanoimaging.Here we demonstrate a Fabry–Pérot resonance flat-based plasmonic fiber probe(FPFP).The simulation results show that the probe can obtain a nanofocusing spot at the tip with the radially polarized mode.The Fabry–Pérot interference structure is used to control the plasmon propagation on the surface of the probe,it effectively improves the local spot intensity at the tip.Furthermore,the experimental results verify that the FPFP(tip curvature radius is 20 nm)prepared by chemical etching method can obtain a nanofocusing spot at the tip.The nanoimaging of the gold slit structure demonstrates the nanoimaging capability of the FPFP,the 36.9 nm slit width is clearly identified by the FPFP.
基金This work was supported by the China National Funds for Distinguished Young Scientists(No.52225507)the National Key Research and Development Program of China(No.2021YFF0700402)the Fundamental Research Funds for the Central Universities.
文摘Flexible photodetectors are fundamental components for developing wearable systems,which can be widely used for medical detection,environmental monitoring and flexible imaging.However,compared with 3D materials,lowdimensional materials have degraded performance,a key challenge for current flexible photodetectors.Here,a highperformance broadband photodetector has been proposed and fabricated.By combining the high mobility of graphene(Gr)with the strong light–matter interactions of single-walled carbon nanotubes(SWCNTs)and molybdenum disulfide(MoS2),the flexible photodetector exhibits a greatly improved photoresponse covering the visible to near-infrared range.Additionally,a thin layer of gadolinium iron garnet(Gd_(3)Fe_(5)O_(12),GdlG)film is introduced to improve the interface of the double van der Waals heterojunctions to reduce the dark current.The SWCNT/GdIG/Gr/GdIG/MoS2 flexible photodetector exhibits a high photoresponsivity of 47.375 A/W and a high detectivity of 1.952×1012 Jones at 450 nm,a high photoresponsivity of 109.311 A/W and a high detectivity of 4.504×10^(12) Jones at 1080 nm,and good mechanical stability at room temperature.This work demonstrates the good capacity of GdIGassisted double van der Waals heterojunctions on flexible substrates and provides a new solution for constructing high-performance flexible photodetectors.
基金The authors would like to thank the National Science Fund for Excellent Young Scholars(51722509)National Key Research and Development Program of China(2017YFB1104700)+1 种基金Program for Science and Technology Innovation Group of Shaanxi Province(2019TD-011)Key Research and Development Program of Shaanxi Province(2020ZDLGY04-02)for support.
文摘In this work,the electrical property of Au/graphene oxide/p-InP hetero-structure has been evaluated by 1-V and C-V measure-ments in dark and iluminated conditions(visible light).The diode exhibited significant rectifying behavior,thus indicating the heterojunction-lype diode.The key electrical parameters of heterojunction diode including ideality factor(n),series resistance(R),shunt resistance(Rsh),and barrier height(Фb)are estimated from I-V data based on the theory of thermionic emission.The modifed Norde and Cheung's methods were utilized to evaluate the electrical parameters and compared the results.The current conduction mechanism at different voltage regions of I-V has also been investigated.The variation of 1/C versus voltage signifies linearity at high frequency(1 MHz),indicating that the type of heterojunction can be abrupt.The experimental outcomes of this study revealed that the performance of heterojunction diode in dark is considerably good as compared to the ilumination condition with respect to the lower values of Фp,n,R,and interface state density(Nss).
基金The authors would like to acknowledge the support by the National Science Fund for Distinguished Young Scholars(No.52225507)the National Key Research and Development Program of China(No.2021YFF0700402)the Key Research and Development Program of Shaanxi Province(No.2021GXLH-Z-029).
文摘Delivering light to the nanoscale using a flexible and easily integrated fiber platform holds potential in various fields of quantum science and bioscience.However,rigorous optical alignment,sophisticated fabrication process,and low spatial resolution of the fiber-based nanoconcentrators limit the practical applications.Here,a broadband azimuthal plasmon interference nanofocusing technique on a fiber-coupled spiral tip is demonstrated for fiber-based near-field optical nanoimaging.The spiral plasmonic fiber tip fabricated through a robust and reproducible process can reverse the polarization and modulate the mode field of the surface plasmon polaritons in three-dimensionally azimuthal direction,resulting in polarization-insensitive,broad-bandwidth,and azimuthal interference nanofocusing.By integrating this with a basic scanning near-field optical microscopy,a high optical resolution of 31 nm and beyond is realized.The high performance and the easy incorporation with various existing measurement platforms offered by this fiber-based nanofocusing technique have great potential in near-field optics,tip-enhanced Raman spectroscopy,nonlinear spectroscopy,and quantum sensing.
基金support from the National Science Fund for Distinguished Young Scholars(No.52225507)the National Key Research and Development Program of China(No.2021YFF0700402)the Fundamental Research Funds for the Central Universities.
文摘Photodetectors(PDs)play a crucial role in imaging,sensing,communication systems,etc.Graphene(Gr),a leading two-dimensional material,has demonstrated significant potential for photodetection in recent years.However,its relatively weak interaction with light poses challenges for practical applications.The integration of silicon(Si)and perovskite quantum dots(PQDs)has opened new avenues for Gr in the realm of next-generation optoelectronics.This review provides a comprehensive investigation of Gr/Si Schottky junction PDs and Gr/PQD hybrid PDs as well as their heterostructures.The operating principles,design,fabrication,optimization strategies,and typical applications of these devices are studied and summarized.Through these discussions,we aim to illuminate the current challenges and offer insights into future directions in this rapidly evolving field.
