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InAs on GaAs Photodetectors Using Thin InAlAs Graded Buffers and Their Application to Exceeding Short-Wave Infrared Imaging at 300?K
摘要： Short-wave infrared (SWIR) detectors and emitters have a high potential value in several fields of applications, including the internet of things (IoT) and advanced driver assistance systems (ADAS), gas sensing. Indium Gallium Arsenide (InGaAs) photodetectors are widely used in the SWIR region of 1–3 μm; however, they only capture a part of the region due to a cut-off wavelength of 1.7 μm. This study presents an InAs p-i-n photodetector grown on a GaAs substrate (001) by inserting 730-nm thick inxAl1?xAs graded and AlAs buffer layers between the InAs layer and the GaAs substrate. At room temperature, the fabricated InAs photodetector operated in an infrared range of approximately 1.5–4 μm and its detectivity (D*) was 1.65 × 108 cm · Hz1/2 · W?1 at 3.3 μm. To demonstrate performance, the Sherlock Holmes mapping images were obtained using the photodetector at room temperature.
关键词： InxAl1?xAs graded buffer,InAs p-i-n photodetector,GaAs substrate,room temperature operation,Short-wave infrared (SWIR),InGaAs photodetectors
更新于2025-09-11 14:15:04
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Improved charge transfer, mobility and morphology for high performance panchromatic organic photodetectors by adding PC71BM in P3HT:IEICO-4F
摘要： High performance of panchromatic organic photodetectors (OPDs) with a wide spectral response ranged from 300 to 1000 nm were realized through adding [6,6]-phenyl-C71-butyric acid methylester (PC71BM) fullerene as an electron acceptor into the polymer donor of poly (3-hexylthiophene) (P3HT) and the small molecular non-fullerene acceptor of 2, 2′-((2Z,2′Z)-(((4, 4, 9, 9-tetrakis(4-hexylphenyl)-4, 9-dihydro-sindaceno[1, 2-b:5, 6-b′] dithiophene-2, 7-diyl)bis(4-((2-ethylhexyl)oxy)thiophene-5, 2-diyl))bis-(methanylylidene))bis(5, 6-di?uoro-3-oxo-2, 3-dihydro-1H-indene-2, 1-diylidene))dimalononitrile (IEICO-4F) host system. The fabricated OPD exhibited a high detectivity (D*) of 1.35 × 1012 Jones at 805 nm by adding 10 wt% PC71BM, which is 1.5 folds higher than it from the control system. The improved performance was mainly attributed to the increased light absorption in the short wavelength range and cascade energy level alignment, which is responsible for the e?cient light harvesting and exciton utilization. Furthermore, the active layer morphology was optimized by adjusting the ratio of PC71BM acceptor, which e?ciently enhances charge transport and mobility of the device as well as suppress bimolecular recombination. This work indicates that adding fullerene into non-fullerene system plays a positive e?ect on the device performance of panchromatic OPDs.
关键词： Film morphology,Charge mobility,Non-fullerene and fullerene acceptors,Panchromatic organic photodetector,Charge transfer
更新于2025-09-11 14:15:04
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Polarimetric Three-Dimensional Topological Insulators/Organics Thin Film Heterojunction Photodetectors
摘要： As a state of quantum matter with insulating bulk and gapless surface states, topological insulators (TIs) have huge potential in optoelectronic devices. On the other hand, polarization resolution photoelectric devices based on anisotropic materials have overwhelming advantages in practical applications. In this work, the 3D TIs Bi2Te3/organics thin film heterojunction polarimetric photodetectors with high anisotropic mobility ratio, fast response time, high responsivity, and EQE in broadband spectra are presented. At first, the maximum anisotropic mobility ratio of the Bi2Te3/organics thin film can reach 2.56, which proves that Bi2Te3 can serve as a sensitive material for manufacturing polarization photoelectric devices. Moreover, it is found that the device can exhibit a broad bandwidth and ultrahigh response photocurrent from visible to middle wave infrared spectra (405?3500 nm). The highest responsivity (Ri) of the device can still reach 1.93 AW?1 at 3500 nm. In addition, the ultrahigh external quantum efficiency is 4534% with a fast response time (1.42 ms). Excellent properties mentioned above indicate that TIs/organics heterojunction devices are suitable for manufacturing high-performance photoelectric devices in infrared region.
关键词： polarization resolved,inorganics/organics heterojunction,photodetector,Bi2Te3 thin film,MWIR photodetectors
更新于2025-09-11 14:15:04
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A 2.6 μW Monolithic CMOS Photoplethysmographic (PPG) Sensor Operating with 2 μW LED Power for Continuous Health Monitoring
摘要： Photoplethysmography (PPG) enables wearable vitals monitoring. Nevertheless, it is still limited by the few mA of the LEDs driving current. We present a PPG sensor integrating an array of dedicated pinned-photodiodes (PPD) with a full readout chain integrated in a 0.18 μm CMOS Image Sensor (CIS) process. The sensor features a total input referred noise of 0.68 e?rms per PPD, independently of the input light, and achieves a 4.6 μW total power consumption, including the 2 μW LED power, at 1.38 bpm heart rate average error.
关键词： CMOS,wearable,CIS,PPG,low-power,low-noise,LED,Array,PPD,Photodetector
更新于2025-09-11 14:15:04
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Self‐Powered UV–Vis–NIR Photodetector Based on Conjugated‐Polymer/CsPbBr <sub/>3</sub> Nanowire Array
摘要： Perovskite photodetectors have attracted intensive research interest due to promising applications in sensing, communication, and imaging. However, their performance is restricted by the narrow spectrum range, required power source, and instability in ambient environment. To address these issues, a self-powered photodetector based on the inorganic CsPbBr3 perovskite nanowire array/conjugated-polymer hybrid structure is designed. The spectra response range of the device can be extended to 950 nm, along with outstanding stability, fast response speed (111/306 μs), and large detectivity (1.2 × 1013 Jones). The performance parameters are comparable to or even better than most reported CsPbBr3 and conjugated-polymer photodetectors. The excellent performance is mainly attributed to the efficient carrier generation, separation, and transport resulting from array structure and favorable band structure.
关键词： CsPbBr3,photodetector,perovskite,diffraction grating,self-powered
更新于2025-09-11 14:15:04
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A Kirigami Concept for Transparent and Stretchable Nanofiber Networks-based Conductors and UV Photodetectors
摘要： To meet the increasing demand for wearable electronics today, fabrication of the stretchable devices becomes crucial. In this respect, a stretchable conductor is an essential component for achieving stretchability of the device. Herein, a stretchable and transparent conductor unit, Au-metallized PVP (Au@PVP) nanofiber network on a kirigami-structured PDMS substrate, was newly developed. By a series of comparative studies, the effectiveness of our strategies to the sensing material owing to its high sensitivity for UV light and large surface to volume ratio. To point out its applicability, we fabricated a transparent and stretchable photodetector having the same geometry. ZnO nanorod, the 1D transparent metal oxide nanostructure, is used as a resistance, ~50% increase. It also exhibited ~80% transparency, as well as excellent durability. stretchable conductor showed high stretchability of 110% without significant change in invariant electrical conductivity and high stretchability is convincingly demonstrated. Our The resulting device showed outstanding ON/OFF ratio of 1020 at its original state and 440 under 80% strain. Its fast response/reset time, high transparency and stable performance indicate the feasibility of the stretchable and transparent optoelectronic device.
关键词： metal nanofiber network,transparent,photodetector,wearable electronics,kirigami,stretchable
更新于2025-09-11 14:15:04
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Interface Defect Engineering for Improved Graphene-Oxide-Semiconductor Junction Photodetectors
摘要： The deeply depleted graphene-oxide-semiconductor (D2GOS) junction detector provides an effective architecture for photodetection enabling direct readout of photogenerated charge. Due to an inherent gain mechanism proportional to graphene’s high mobility (μ), this detector architecture exhibits large responsivities and signal-to-noise ratios (SNR). The ultimate sensitivity of the D2GOS junction detector may be limited, however, due to the generation of dark charge originating from interface states at the semiconductor/dielectric junction. Here, we examine the performance limitations caused by dark charge and demonstrate its mitigation via the creation of low interface defect junctions enabled by surface passivation. The resulting devices exhibit responsivities exceeding 10,000 A/W—a value which is 10x greater than that of analogous devices without the passivating thermal oxide. With cooling of the detector, the responsivity further increases to over 25,000 A/W, underscoring the impact of surface generation on performance and thus the necessity of minimizing interfacial defects for this class of photodetector.
关键词： 2D Materials,Photodetector,Interface Defects,GOS Junction,2D Detector,Graphene,High Responsivity
更新于2025-09-11 14:15:04
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Enhanced photo-sensitivity in a Si photodetector using a near-field assisted excitation
摘要： Silicon is an indispensable material in electric device technology. However, Si is an indirect bandgap material; therefore, its excitation efficiency, which requires phonon assistance, is low under propagating far-field light. To improve the excitation efficiency, herein we performed optical near-field excitation, which is confined in a nano-scale, where the interband transitions between different wave numbers are excited according to the uncertainty principle; thus, optical near-field can directly excite the carrier in the indirect bandgap. To evaluate the effect of optical near-field confined in a nano-scale, we fabricate the lateral Si p–n junction with Au nanoparticles as sources to generate the field confinement. We observed a 47.0% increase in the photo-sensitivity rate. In addition, by using the thin lateral p–n junction, which eliminates the far-field excitation, we confirmed a 42.3% increase in the photo-sensitivity rate.
关键词： optical near-field,Au nanoparticles,photo-sensitivity,Silicon,photodetector
更新于2025-09-11 14:15:04
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Electron Depleted ZnO Nanowalls based Broadband Photodetector
摘要： Pristine ZnO has been extensively reported for high responsivity UV photodetectors based applications. However, in general, its photo-response in visible and NIR region is very poor. In this article, a simple and cost-effective technique of synthesizing pristine ZnO honeycomb nanostructure based high responsivity broadband (200 nm - 950 nm) photodetector is demonstrated. The dark current of the device was found to be as low as 5.6 pA at 10 V applied bias. The maximum photo-current to dark current ratio was ~3.2 x 107 at 300 nm wavelength (measured at -10 V applied bias). The calculated linear dynamic range of the device is as high as 128.9 dB. The maximum specific photodetectivity, photoresponsivity and external quantum efficiency (@ 300 nm) calculated at -10 V bias was 2.07x1015 cm·Hz1/2·W-1, 115 A·W-1 and 47,583% respectively, which is comparable to some of the existing commercial broadband photodetectors.
关键词： Honeycomb,ZnO,Photodetector,Hydrothermal
更新于2025-09-11 14:15:04
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Postannealed Structural Relaxation and Phase Evolution of Quaternary Alloy BeMgZnO
摘要： The thermal stability of quaternary alloy BeMgZnO was investigated in this study. When a Be0.09Mg0.19Zn0.72O alloy film was annealed, structural relaxation and reconstruction of the film layers were found at 600, 700, and 800 °C. Be atoms were found to gradually diffuse out from the host lattice, and Mg atoms were still maintained. As a result, a mixed-phase alloy containing BeO and MgxZn1?xO was continuously generated. Correspondingly, the bandgap of Be0.09Mg0.19Zn0.72O reduced because of the diffusion of Be atoms. Hence, the thermodynamic solubility of BeO in ZnO and MgO was demonstrated to be relatively low. Additionally, the aging effect caused by a higher annealing temperature is more effective than that caused by a lower annealing temperature for a longer time. Due to the improvement of crystal quality, an MSM interdigital structure photodetector based on the 800 °C annealed sample was fabricated and revealed a strong response to the UV light. Our finding provides a new understanding of the ultrawide bandgap quaternary alloy BeMgZnO and contributes to a significant step toward its practical applications.
关键词： bandgap,photodetector,Be diffusion,BeMgZnO,thermal annealing,structural relaxation
更新于2025-09-11 14:15:04