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Interlayer Transition in a vdW Heterostructure toward Ultrahigh Detectivity Shortwave Infrared Photodetectors
摘要： Van der Waals (vdW) heterostructures of 2D atomically thin layered materials (2DLMs) provide a unique platform for constructing optoelectronic devices by staking 2D atomic sheets with unprecedented functionality and performance. A particular advantage of these vdW heterostructures is the energy band engineering of 2DLMs to achieve interlayer excitons through type-II band alignment, enabling spectral range exceeding the cutoff wavelengths of the individual atomic sheets in the 2DLM. Herein, the high performance of GaTe/InSe vdW heterostructures device is reported. Unexpectedly, this GaTe/InSe vdWs p–n junction exhibits extraordinary detectivity in a new shortwave infrared (SWIR) spectrum, which is forbidden by the respective bandgap limits for the constituent GaTe (bandgap of ≈1.70 eV in both the bulk and monolayer) and InSe (bandgap of ≈1.20–1.80 eV depending on thickness reduction from bulk to monolayer). Specifically, the uncooled SWIR detectivity is up to ≈1014 Jones at 1064 nm and ≈1012 Jones at 1550 nm, respectively. This result indicates that the 2DLM vdW heterostructures with type-II band alignment produce an interlayer exciton transition, and this advantage can offer a viable strategy for devising high-performance optoelectronics in SWIR or even longer wavelengths beyond the individual limitations of the bandgaps and heteroepitaxy of the constituent atomic layers.
关键词： interlayer transitions,2D materials,vdW heterostructures,broadband photodetectors,shortwave infrared
更新于2025-09-19 17:13:59
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Progress of Photodetectors Based on the Photothermoelectric Effect
摘要： High-performance uncooled photodetectors operating in the long-wavelength infrared and terahertz regimes are highly demanded in the military and civilian fields. Photothermoelectric (PTE) detectors, which combine photothermal and thermoelectric conversion processes, can realize ultra-broadband photodetection without the requirement of a cooling unit and external bias. In the last few decades, the responsivity and speed of PTE-based photodetectors have made impressive progress with the discovery of novel thermoelectric materials and the development of nanophotonics. In particular, by introducing hot-carrier transport into low-dimensional material–based PTE detectors, the response time has been successfully pushed down to the picosecond level. Furthermore, with the assistance of surface plasmon, antenna, and phonon absorption, the responsivity of PTE detectors can be significantly enhanced. Beyond the photodetection, PTE effect can also be utilized to probe exotic physical phenomena in spintronics and valleytronics. Herein, recent advances in PTE detectors are summarized, and some potential strategies to further improve the performance are proposed.
关键词： thermoelectrics,low-dimensional materials,photothermoelectric effect,photodetectors,nanophotonics
更新于2025-09-19 17:13:59
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Hierarchical structures and multiscale optical coupling for improved photodetectors
摘要： Hierarchical structures comprise of patterns which are themselves structured at lower length scales. Such structures can outperform the performance limits posed by continuum and non-hierarchical structures. However, the possible role of hierarchical structuring in photonics and optoelectronics are not well understood. Here we report on the implications of using materials structured at multiple length scales in the design of spectrally uniform photodetectors. We present our results on the design and fabrication of hierarchical structures comprising of alternating planar and nanostructured microscale domains interspersed with nanoscale objects. These structures show the possibility of obtaining unusual control over the flow of light compared to conventional non-hierarchical structures through the coupling of light across micro-domains. These multiscale structures are fabricated using self-assembly and a novel mechanical strain- augmented template based nano-molding process. We fabricate in a random multi-periodic nanostructures embedded distribution of micro-domains, using an initial template which has only monoperiodic structures. Organic photodetectors fabricated on these molded multiscale platforms show considerable improvements in spectral uniformity. This design advantage arises through the multiscale optical processes which preferentially filter light entering the absorber, which occur only in a hierarchically structured device. In summary, this paper explores unusual ways to control the flow of light using hierarchical structures. On the optoelectronic design front, hierarchical structures are seen to improve the spectral uniformity of photodetectors beyond the limits of continuum and non-hierarchical material design. Further, this effort pushes the limits of monodisperse self-assembly to fabricate static multiperiodic structures, using facile mechanical strain augmented nanofabrication, which was hitherto a challenge.
关键词： multiscale,hierarchical,optoelectronics,photodetectors,self-assembly,photonics
更新于2025-09-19 17:13:59
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Bolometric Effect in Bi <sub/>2</sub> O <sub/>2</sub> Se Photodetectors
摘要： Bi2O2Se is emerging as a photosensitive functional material for optoelectronics, and its photodetection mechanism is mostly considered to be a photo-conductive regime in previous reports. Here, the bolometric effect is discovered in Bi2O2Se photodetectors. The coexistence of photoconductive effect and bolometric effect is generally observed in multiwavelength photoresponse measurements and then confirmed with microscale local heating experiments. The unique photoresponse of Bi2O2Se photodetectors may arise from a change of hot electrons during temperature rises instead of photoexcited holes and electrons. Direct proof of the bolometric effect is achieved by real-time temperature tracking of Bi2O2Se photodetectors under time evolution after light excitation. Moreover, the Bi2O2Se bolometer shows a high temperature coefficient of resistance (?1.6% K?1), high bolometric coefficient (?31 nA K?1), and high bolometric responsivity (>320 A W?1). These findings offer a new approach to develop bolometric photodetectors based on Bi2O2Se layered materials.
关键词： bolometric effect,photodetectors,Bi2O2Se
更新于2025-09-19 17:13:59
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<i>(Invited)</i> Mid-Infrared Colloidal Quantum Dot Based Nanoelectronics and Nano-Optoelectronics
摘要： Electronic and optoelectronic devices fabricated from colloidal quantum dots (CQDs) provide a promising path toward realizing low-cost devices with greatly simplified device fabrication procedure, owing to their solution-processability. The impact that CQD technology would bring is expected to be significant, especially in the mid-infrared application areas, which is currently dominated by epitaxial semiconductor technologies. In this work, we introduce a new generation of infrared CQDs, namely Ag2Se CQDs, which has been recently uncovered to show distinct optical absorption in the mid-infrared. We report on the fabrication of solution-processed photoconductive photodetectors and discuss our analyses on the electronic and optoelectronic characteristics of our devices. We also demonstrate the feasibility of mid-infrared photodetection with a measured peak responsivity of 0.16 mA/W at 4 μm under room temperature operation.
关键词： Ag2Se,solution-processability,photodetectors,mid-infrared,colloidal quantum dots
更新于2025-09-19 17:13:59
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Interfacial‐Tunneling‐Effect‐Enhanced CsPbBr <sub/>3</sub> Photodetectors Featuring High Detectivity and Stability
摘要： Inorganic halide perovskite (HP)-based photodetectors (PDs) have exhibited fast response speed and high responsivity, but with low detectivity due to the high dark current of devices. Additionally, the intrinsic instability of HPs and interface deterioration originating from ion migration inhibit their practical applications severely. A tunneling organic layer is introduced to solve both these problems. Light-induced charge carriers can flow across the interfacial (poly(methyl methacrylate), PMMA) layer with appropriate thickness via the Fowler–Nordheim tunneling effect. Due to the effective control of dark current, the photo-/dark-current ratio reaches a giant value of 2.13 × 108, and the peak detectivity is as high as 1.24 × 1013 Jones. With such superiority, light signal as weak as 244 pW is accurately imaged by a PD array. Additionally, the hydrophobic organic layer inhibits the destruction of HPs caused by moisture and ion migration induced interface reaction, and negligible response attenuation is observed during continuous work in a humid environment for 48 h. This heterojunction structure design provides a new strategy to enhance the performance and stability of perovskite-based photoelectric and photovoltaic devices.
关键词： tunneling effect,photodetectors,halide perovskites
更新于2025-09-19 17:13:59
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Seed‐Initiated Synthesis and Tunable Doping Graphene for High‐Performance Photodetectors
摘要： Due to the promising utilizations in nanoelectronics, doping-tunable graphene is paid extensive attentions. Nevertheless, a harmless approach to dope/co-dope graphene in a controllable and easy way with low cost is still unattainable. Herein, through seeding of 0D N & S dual-doped graphene quantum dots (N & S dual-doped GQDs) on a catalytic substrate and then dynamic chemical vapor deposition (CVD), a monolayered dual-doped graphene film is demonstrated. The concentrations of dopants in graphene are strictly discerned in accordance with preliminary seeding for dual-doped GQDs. Through the monitoring of growing process, the research elucidates the growth mechanism of the graphene, and unveils that dual-doped GQDs can serve as the nucleation centers for creating doped-graphene films by 2D epitaxial growth and thus graphene with designed dopant concentration can be obtained. Finally, the photodetector built on N & S dual-doped graphene film is found to perform satisfactorily, accompanying high detectivity (≈1.42 × 1010 cm Hz1/2 W?1) and responsivity (61 mA W?1), at wavelength of 1550 nm. The research proposes a dexterous approach for synthesizing tunably doped graphene films by the combination of locally controlled nucleation seeds and in situ CVD, which lays the foundation for applying graphene in industries of photonic and electronic devices.
关键词： growth mechanism,doping-tunable graphene,photodetectors,seed-initiated synthesis
更新于2025-09-19 17:13:59
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ZnO‐Based Ultraviolet Photodetectors with Tunable Spectral Responses
摘要： Conventionally, wavelength-selective ultraviolet photodetection is achieved by using broadband inorganic photodiodes coupled with optical ?lters, which signi?cantly increases the complexity and fabricating cost of devices for high pixel density imaging systems. Here, a facile approach to achieve tunable spectral response without ?lters is demonstrated. The devices are based on ZnO heterojunctions, and the response spectra are effectively modulated by tuning the position of charge generation, which results in distinct charge-collection ef?ciencies. After optimization, the ZnO/poly[bis(4-phenyl)(2,4,6-trimethylphenyl) amine] (PTAA) photodiodes exhibit narrowband ultraviolet (UV) response with a full width at half maximum (FWHM) of <25 nm, and the NiOx/ZnO devices reveal relatively broader photoresponse. All of these devices demonstrate relatively low dark currents and noises, high responsivities and detectivities, and fast response speeds. This work proves the great potential of ZnO thin ?lms for UV detection and also ?rst provides an alternative approach to effectively tune the spectral response.
关键词： atomic layer deposition,narrowband,tunable spectral response,ZnO-based photodiodes,ultraviolet photodetectors
更新于2025-09-19 17:13:59
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Nitrogen‐functionalized Graphene Quantum Dots: A Versatile Platform for Integrated Optoelectronic Devices
摘要： Over the past 10 years, graphene quantum dots (GQDs) have grown into a highly innovative optical material in various research fields including electronics, photonics, biotechnologies, etc. With the increasing implementation of GQDs in these fields, GQDs with tunable optical properties will emerge that could be especially suitable for applications in the field of integrated photonics. Herein, a short summary of the recent state of our research on the development of nitrogen-functionalized GQDs with tunable optical properties and their integration into photodetectors is given.
关键词： Optical properties,Photodetectors,Chemical functionalization,Graphene,Graphene quantum dots
更新于2025-09-19 17:13:59
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HgCdTe-Based 640 ?? 512 Matrix Midwave Infrared Photodetector
摘要： Matrix photosensitive elements based on a HgCdTe semiconductor solid solution on silicon substrates with 640 × 512 elements at a pitch of 25 μ m with a long-wavelength sensitivity of 5 μ m at half maximum are designed and produced. The scheme and topology are developed according to which matrix multiplexers with 640 × 512 elements at a pitch of 25 μ m, which ensure operating modes at a clock frequency up to 10 MHz, are manufactured. Using a hybrid assembly method on indium bumps, a matrix photodetector with 640 × 512 elements at a pitch of 25 μ m is produced. The best photodetector specimens are characterized by the following parameters: average NETD value <13 mK and the number of workable elements > 99.5%.
关键词： SWaP,MBE,MCT,photodetectors,FPA,NETD
更新于2025-09-19 17:13:59