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Theoretical correlation and effect of annealing on the photoresponse of vertically strain-coupled In <sub/>0.5</sub> Ga <sub/>0.5</sub> As/GaAs quantum dot heterostructures
摘要： Here, we propose a di?erent approach for growing strain-coupled In0.5Ga0.5As quantum dot infrared photodetectors (QDIPs) with varying dot layer periodicity. Strain calculation is done throughout the quantum dot (QD) heterostructures, which has a signi?cant e?ect on the carrier probability density functions. The localization of the electron probability density function in each heterostructure has a strong correlation with the photoresponse. The con?ned electron wavefunction in the top QD layer of the optimized device heterostructure (trilayer QDIP having dot layer periodicity of three) would be useful for hyperspectral imaging applications owing to its narrow (8.67 meV) photoresponse. Rapid thermal annealing treatment was carried out on the trilayer QDIP to investigate the enhancement in its optoelectronic properties. The dark current density reduced by two orders, and the operating temperature increased by 30 °C for the 650 °C-annealed counterpart. Also, the responsivity enhanced by two times (2.05 A/W at ?1 V) for the annealed QDIP.
关键词： In0.5Ga0.5As,rapid thermal annealing,photoresponse,strain-coupled,quantum dot infrared photodetectors
更新于2025-09-12 10:27:22
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Photomultiplication Type Broad Response Organic Photodetectors with One Absorber Layer and One Multiplication Layer
摘要： Broad response organic photodetectors (OPDs) with photomultiplication (PM) effect are achieved with one absorber layer and one multiplication layer. The response range of the PM-OPDs is primarily determined by materials in the absorber layer, the external quantum efficiency (EQE) of the PM-OPDs is mainly controlled by the multiplication layer. Here, double-layered PM-OPDs were designed with the structure of ITO/ZnO/PM6:Y6/PC71BM:P3HT (100:5, wt/wt)/Au, where PM6:Y6 is employed as absorber layer and PC71BM:P3HT is used as multiplication layer. The optimal PM-OPDs exhibit broad response covering 350-950 nm. Meanwhile, the optimal PM-OPDs exhibit the largest EQE value of ~1200% and the maximum specific detectivity (D*) of ~6.8 × 10-12 cm Hz1/2 W-1 under 10 V bias. This double-layered approach may be a smart strategy to realize PM-OPDs with easily adjustable response range.
关键词： Organic photodetectors,Photomultiplication,Absorber layer,Multiplication layer,Broad response
更新于2025-09-12 10:27:22
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Large-Scale Growth of Ultrathin Low-Dimensional Perovskite Nanosheets for High-Detectivity Photodetectors
摘要： Low-dimensional organic-inorganic hybrid perovskites have demonstrated to be promising semiconductor materials due to their unique optoelectronic properties, however, the controllable growth of high-quality ultrathin 2D perovskites with large lateral dimension still faces great challenges. Herein, we report the controllable growth of large-scale ultrathin 2D (C6H5(CH2)3NH3)3Pb2I7 ((PPA)3Pb2I7) perovskite nanosheets (NSs) using a facile antisolvent-assisted crystallization approach under mild condition. As a result, the well-defined regular-shaped (PPA)3Pb2I7 NSs, with the largest lateral size over 100 micrometers, have been successfully synthesized, which is more than several ten times larger than that of other 2D perovskites NSs previously reported. Moreover, the thickness of the achieved 2D perovskite NSs can be well-tuned by altering the concentration of the precursor solution, with the smallest thickness down to ~4.7 nm. More importantly, the photodetectors based on the high-quality (PPA)3Pb2I7 perovskites exhibit fascinating performance, including an extremely low dark current (~1.5 pA), fast response/recovery rate (~850/780 μs) and high detectivity (~1.2×1010 Jones). This work provides a simple and promising strategy to controllably grow large-scale and ultrathin 2D perovskite NSs for low-cost and high-performance optoelectronic devices.
关键词： low-dimensional perovskite,antisolvent-assisted crystallization approach,large size,photodetectors,ultrathin,nanosheets
更新于2025-09-12 10:27:22
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Back-to-back Schottky junction photodetectors based on CVD grown CsPbBr <sub/>3</sub> microcrystalline striped films
摘要： In recent years, a new type of lead halide perovskite has attracted a lot of attention for next-generation photodetectors (PDs) with high responsivity, good detectivity, and fast photoresponse speed. Specifically, cesium based all-organic perovskites exhibit better photostability and therefore have achieved increasing success in PDs recently. For reducing the leak current and increasing the response speed of photo-conductive PDs, back-to-back Schottky junction PD is designed and fabricated through a direct growth approach of CsPbBr3 microcrystal (MC) films on indium tin oxide (ITO) electrodes by the chemical vapor deposition (CVD) method. Due to the enhanced Schottky barrier height and threshold voltage between CsPbBr3 and ITO electrodes, the PD exhibits the on/off ratio of up to 104, peak responsivity of 3.9 AW?1, detectivity of 3.8 × 1012, and fast response speed of 0.22 ms (rise time) and 0.45 ms (decay time). In addition, the stability of PD is also enhanced by the high crystal quality of CVD grown CsPbBr3 MCs.
关键词： microcrystalline films,Schottky junction,photodetectors,CsPbBr3,chemical vapor deposition
更新于2025-09-12 10:27:22
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Optoelectronic response of hybrid PbS-QD/graphene photodetectors
摘要： Lead sulfide quantum dots (QDs) have been widely used for various optoelectronic devices due to their high absorption coefficient and tunable bandgap. However, the low mobility of QD films results in poor charge collection and device performance. By combining QDs with graphene into hybrid graphene/QD photodetectors, photocarriers from QDs are transferred to graphene, improving charge collection and transport, drastically increasing the photoresponsivity. Herein, we carry a systematic analysis on how critical tuning parameters such as QD size and QD film thickness affect responsivity, spectral response, and time response. We report the absorption coefficient, refractive index (n, k), penetration depth, and energy bandgap of PbS QDs of different sizes. We study systematically how the photocurrent, photoresponsivity, time response, and power density dependence vary with QD size in hybrid Gr/QD. The bandgap of lead sulfide quantum dots was size-tuned between 0.86 and 1.39 eV. The time response shows that subsecond modulation can be achieved for different QD sizes with a responsivity up to 107 A/W at power densities of 10?5 mW/cm2. We also studied how the performance of the photodetectors is affected by the thickness, discussing the limitations on the thickness by the compromise between light absorption and charge collection. We describe how the optical response shifts toward the infrared as QD films get thicker. Time responses below 1 s are obtained for graphene/QD devices with thickness from 150 nm to 1 μm. This systematic study provides important guidelines to design hybrid graphene/QD photodetectors and tune their spectral response and performance.
关键词： hybrid devices,optoelectronic response,PbS quantum dots,photodetectors,graphene
更新于2025-09-12 10:27:22
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Germanium quantum dot infrared photodetectors addressed by self-aligned silicon nanowire electrodes
摘要： Germanium quantum dots (GeQDs), addressed by self-aligned and epitaxial silicon nanowires (SiNWs) as electrodes, represent the most fundamental and the smallest units that can be integrated into Si optoelectronics for 1550 nm wavelength detection. In this work, individual GeQD photodetectors have been fabricated based on a low temperature self-condensation of uniform amorphous Si (a-Si)/a-Ge bilayers at 300 oC, addressed by self-aligned silicon nanowire electrodes. The photodetectors demonstrate a responsivity of 1.5 mA/W and a photoconductive gain exceeding 102 to the communication wavelength signals, which are related to the beneficial type-II Ge/Si alignment, gradient Ge/Si epitaxial transition and a larger QD/NW diameter ratio. Importantly, this hetero GeQD/SiNW photodetectors can be deployed into predesigned locations for scalable device fabrication. These results indicate a new approach to batch-fabricate and integrate GeQDs for ultra-compact Si-compatible photodetection and imaging applications.
关键词： Ge quantum dots,self-condensation,photodetectors,Si nanowires
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Design and Analysis of Tensile-Strained GeSn Mid-Infrared Photodetectors on Silicon
摘要： We present a design of tensile-strained GeSn photodetectors on silicon substrate with SiN stressors. The strained band structure, absorption coefficient, and optical responsivity are calculated and discussed.
关键词： silicon photonics,tensile strain,photodetectors,mid-infrared,GeSn
更新于2025-09-12 10:27:22
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Suppression of persistent photoconductivity AlGaN/GaN heterostructure photodetectors using pulsed heating
摘要： This paper demonstrates a method to reduce the decay time in AlGaN/GaN photodetectors by pulsed heating mode. A suspended AlGaN/GaN heterostructure photodetector integrated with micro-heater is fabricated and characterized under ultraviolet illumination. We have observed that the course of persistent photoconductivity (PPC) was effectively accelerated by applying pulsed heating. The decay time is significantly reduced from 175 s by DC heating to 116 s by 50 Hz pulsed heating at the same power (280 mW). With the same pulse duty cycle and 50 Hz pulsed heating frequency, a reduction of 30-45 % in decay time is measured compared to DC heating.
关键词： pulsed heating,persistent photoconductivity,decay time,AlGaN/GaN heterostructure,photodetectors
更新于2025-09-11 14:15:04
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Beyond Gold: Spin‐Coated Ti <sub/>3</sub> C <sub/>2</sub> ‐Based MXene Photodetectors
摘要： 2D transition metal carbides, known as MXenes, are transparent when the samples are thin enough. They are also excellent electrical conductors with metal-like carrier concentrations. Herein, these characteristics are exploited to replace gold (Au) in GaAs photodetectors. By simply spin-coating transparent Ti3C2-based MXene electrodes from aqueous suspensions onto GaAs patterned with a photoresist and lifted off with acetone, photodetectors that outperform more standard Au electrodes are fabricated. Both the Au- and MXene-based devices show rectifying contacts with comparable Schottky barrier heights and internal electric fields. The latter, however, exhibit significantly higher responsivities and quantum efficiencies, with similar dark currents, hence showing better dynamic range and detectivity, and similar sub-nanosecond response speeds compared to the Au-based devices. The simple fabrication process is readily integratable into microelectronic, photonic-integrated circuits and silicon photonics processes, with a wide range of applications from optical sensing to light detection and ranging and telecommunications.
关键词： work-function,MXene,semiconductors,Schottky contacts,photodetectors
更新于2025-09-11 14:15:04
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A Highly Responsive Organic Image Sensor Based on a Two‐Terminal Organic Photodetector with Photomultiplication
摘要： Highly responsive organic image sensors are crucial for medical imaging applications. To enhance the pixelwise photoresponse in an organic image sensor, the integration of an organic photodetector with amplifiers, or the use of a highly responsive organic photodetector without an additional amplifying component, is required. The use of vertically stacked, two-terminal organic photodetectors with photomultiplication is a promising approach for highly responsive organic image sensors owing to their simple two-terminal structure and intrinsically large responsivity. However, there are no demonstrations of an imaging sensor array using organic photomultiplication photodetectors. The main obstacle to a sensor array is the weak-light sensitivity, which is limited by a relatively large dark current. Herein, a highly responsive organic image sensor based on monolithic, vertically stacked two-terminal pixels is presented. This is achieved using pixels of a vertically stacked diode-type organic photodetector with photomultiplication. Furthermore, applying an optimized injection electrode and additionally stacked rectifying layers, this two-terminal device simultaneously demonstrates a high responsivity (>40 A W?1), low dark current, and high rectification under illumination. An organic image sensor based on this device with an extremely simple architecture exhibits a high pixel photoresponse, demonstrating a weak-light imaging capability even at 1 μW cm?2.
关键词： matrices,photomultiplication,sensors,image sensors,organic photodetectors
更新于2025-09-11 14:15:04