Graphene photodetectors integrated with silicon and perovskite quantum dots

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.

A flat-based plasmonic fiber probe for nanoimaging

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.

High-performance broadband flexible photodetector based on Gd_(3)Fe_(5)O_(12)-assisted double van der Waals heterojunctions

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.

Polarization-insensitive plasmon nanofocusing with broadband interference modulation for optical nanoimaging

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.

High-performance photodetector based on an interface engineering-assisted graphene/silicon Schottky junction

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.

Investigation of Illumination Effects on the Electrical Properties of Au/GO/p-lnP Heterojunction with a Graphene Oxide Interlayer

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).