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Toward Broadband Imaging: Surface Engineered PbS Quantum Dot/Perovskite Composite Integrated Ultrasensitive Photodetectors
摘要： PbS colloidal quantum dots (CQDs) passivated by thiocyanate anion (SCN-) are developed to combine with perovskite (CH3NH3PbI3) as building blocks for UV-vis-NIR broadband photodetectors. Both high electrical conductivity and appropriate energy level alignment are obtained by the in situ ligand exchange with SCN-. The PbS-SCN/CH3NH3PbI3 composite photodetectors are sensitive to a broad wavelength range covering the UV-vis-NIR region (365-1550 nm), possessing an excellent responsivity of 255 AW-1 at 365 nm and 1.58 AW-1 at 940 nm, remarkably high detectivity of 4.9×1013 Jones at 365 nm and 3.0×1011 Jones at 940 nm, and a fast response time ≤ 42 ms. Furthermore, a 10×10 photodetector array is fabricated and integrated, which constitutes a high-performance broadband image sensor. Our approach paves a way for the development of highly sensitive broadband photodetectors/imagers that can be easily integrated.
关键词： PbS colloidal quantum dot,surface engineering,perovskite,broadband imaging,photodetectors
更新于2025-09-12 10:27:22
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Monolithic integration of visible GaAs and near-infrared InGaAs for multicolor photodetectors by using high-throughput epitaxial lift-off toward high-resolution imaging systems
摘要： In this study, multicolor photodetectors (PDs) fabricated by using bulk p-i-n-based visible GaAs and near-infrared inGaAs structures were monolithically integrated through a high-throughput epitaxial lift-off (ELO) process. To perform multicolor detection in integrated structures, GaAs PDs were transferred onto inGaAs pDs by using a Y2o3 bonding layer to simultaneously detect visible and near-infrared photons and minimize the optical loss. As a result, it was found that the GaAs top PD and InGaAs bottom PD were vertically aligned without tilting in x-ray diffraction (XRD) measurement. A negligible change in the dark currents for each PD was observed in comparison with reference PDs through electrical characterization. Furthermore, through optical measurements and simulation, photoresponses were clearly revealed in the visible and near-infrared band for the material’s absorption region, respectively. Finally, we demonstrated the simultaneous multicolor detection of the visible and near-infrared region,which implies individual access to each PD without mutual interference. These results are a significant improvement for the fabrication of multicolor PDs that enables the formation of bulk-based multicolor PDs on a single substrate with a high pixel density and nearly perfect vertical alignment for high-resolution multicolor imaging.
关键词： high-resolution imaging,multicolor photodetectors,InGaAs,epitaxial lift-off,GaAs
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) - Investigation of Resonant-Cavity-Enhanced GeSn Photodetectors in Short-Wavelength Infrared Regime
摘要： GeSn with a 10% Sn content for resonant-cavity-enhanced photodetectors (RCE PDs) was grown and the RCE PDs was designed for 2000-nm operation, exhibiting a quantum efficiency up to 91%. This work shows RCE GeSn PDs can be a promising route toward high-response SWIR detection.
关键词： Resonant-cavity-enhanced photodetectors,quantum efficiency,GeSn
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) - Germanium Photodetectors with 60-nm Absorption Coverage Extension and ～2× Quantum Efficiency Enhancement across L-Band
摘要： Germanium-on-insulator (GOI) metal-semiconductor-metal (MSM) photodetectors were demonstrated with a 60 nm extension on the absorption coverage and a ~2× enhancement on the quantum efficiency across the L-band.
关键词： silicon nitride stressor,CMOS-compatible,longer wavelength detection,photodetectors,germanium
更新于2025-09-12 10:27:22
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Organic Photodetectors and their Application in Large Area and Flexible Image Sensors: The Role of Dark Current
摘要： Organic photodetectors (OPDs) have gained increasing interest as they offer cost-effective fabrication methods using low temperature processes, making them particularly attractive for large area image detectors on lightweight flexible plastic substrates. Moreover, their photophysical and optoelectronic properties can be tuned both at a material and device level. Visible-light OPDs are proposed for use in indirect-conversion X-ray detectors, fingerprint scanners, and intelligent surfaces for gesture recognition. Near-infrared OPDs find applications in biomedical imaging and optical communications. For most applications, minimizing the OPD dark current density (Jd) is crucial to improve important figures of merits such as the signal-to-noise ratio, the linear dynamic range, and the specific detectivity (D*). Here, a quantitative analysis of the intrinsic dark current processes shows that charge injection from the electrodes is the dominant contribution to Jd in OPDs. Jd reduction is typically addressed by fine-tuning the active layer energetics and stratification or by using charge blocking layers. Yet, most experimental Jd values are higher than the calculated intrinsic limit. Possible reasons for this deviation are discussed, including extrinsic defects in the photoactive layer and the presence of trap states. This provides the reader with guidelines to improve the OPD performances in view of imaging applications.
关键词： large area image sensors,charge injection,trap states,dark current,flexible image sensors,organic photodetectors
更新于2025-09-12 10:27:22
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Salt‐Assisted Growth of P‐type Cu <sub/>9</sub> S <sub/>5</sub> Nanoflakes for P‐N Heterojunction Photodetectors with High Responsivity
摘要： P-n junctions based on two dimensional (2D) van der Waals (vdW) heterostructure are one of the most promising alternatives in next-generation electronics and optoelectronics. By choosing different 2D transition metal dichalcogenides (TMDCs), the p-n junctions have tailored energy band alignments and exhibit superior performance as photodetectors. The p-n diodes working at reverse bias commonly have high detectivity due to suppressed dark current but suffer from low responsivity resulting from small quantum efficiency. Greater build-in electric field in the depletion layer can improve the quantum efficiency by reducing recombination of charge carriers. Herein, Cu9S5, a novel p-type semiconductor with direct bandgap and high optical absorption coefficient, is synthesized by salt-assisted chemical vapor deposition (CVD) method. The high density of holes in Cu9S5 endows the constructed p-n junction, Cu9S5/MoS2, with strong build-in electric field according to Anderson heterojunction model. Consequently, the Cu9S5/MoS2 p-n heterojunction has low dark current at reverse bias and high photoresponse under illumination due to the efficient charge separation. The Cu9S5/MoS2 photodetector exhibits good photodetectivity of 1.6 × 1012 Jones and photoresponsivity of 76 A W?1 under illumination. This study demonstrates Cu9S5 as a promising p-type semiconductor for high-performance p-n heterojunction diodes.
关键词： Cu9S5,2D metal chalcogenides,photodetectors,van der Waals epitaxy,p-n heterojunctions
更新于2025-09-12 10:27:22
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Facile method for the preparation of high-performance photodetectors with a GQDs/perovskite bilayer heterostructure
摘要： A high-performance nitrogen doped graphene quantum dots (GQDs)/all-inorganic (CsPbBr3) perovskite nanocrystals (NCs) heterostructure photodetector was fabricated on a quartz substrate, using the low cost spin coating technique followed by hot plate annealing. The GQDs/CsPbBr3 NCs heterostructure photodetector exhibits a high overall performance with a photoresponsivity of 0.24 AW?1, on/off ratio of 7.2 × 104, and specific detectivity of up to 2.5 × 1012 Jones. The on/off ratio of the hybrid device was improved by almost ten orders of magnitude, and the photoresponsivity was enhanced almost three times compared to the single layer perovskite NCs photodetector. The performance enhancement of the hybrid device was due to its highly efficient carrier separation at the GQDs/CsPbBr3 NCs interface. This results from the coupling of the GQDs layer, which efficiently extracts and transports the photogenerated carriers, with the CsPbBr3 NCs layer, which has a large absorption coefficient and high quantum efficiency. The interfacial charge transfer from the CsPbBr3 NCs to the GQDs layer was demonstrated by the quenching in the photoluminescence (PL) spectra, and the fast-average decay time in the time-resolved photoluminescence (Trpl) spectra of the hybrid photodetector. Moreover, the performance-enhancement mechanism of the hybrid GQDs/CsPbBr3 photodetector was elucidated by analyzing the band alignment of the GQDs and CsPbBr3 under laser illumination.
关键词： Carrier separation,Charge transfer,CsPbBr3 nanocrystals,Photodetectors,Graphene quantum dots
更新于2025-09-12 10:27:22
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Photocurrent deviation from linearity in an organic photodetector due to limited hole transport layer conductivity
摘要： It has been demonstrated that p-doped polymer layers are a convenient replacement as hole transport layer (HTL) for the widely used Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), yielding comparable photodetection performances at low light intensities. In this work, we aim to evaluate the response of organic photodetectors (OPDs) with increasing light intensity when p-doped PBDTTT-c is used as HTL. Photocurrent linearity measurements are performed on devices processed with both PEDOT:PSS and p-doped PBDTTT-c to better determine the role of the HTL. We show a deviation of the photocurrent from linearity for light intensities above 10?3 W/cm2 at 0 V applied bias due to distinct mechanisms depending on the HTL material. While space charge limited photocurrent (SCLP) explains the non-linearity at high light intensity for the device processed with PEDOT:PSS, bimolecular recombination is responsible for the loss in linearity when p-doped PBDTTT-c is used as HTL. The replacement of PEDOT:PSS by p-doped PBDTTT-c, which is 6 orders of magnitude less conductive, induces Langevin recombination, causing photocurrent non-linearity. Therefore, this study emphasizes the need for highly conductive transport layers when photodetection applications are targeted, and motivates further improvements in organic semiconductor doping.
关键词： Photocurrent linearity,Organic semiconductor doping,Organic photodetectors
更新于2025-09-12 10:27:22
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[ACS Symposium Series] Fundamentals and Applications of Phosphorus Nanomaterials Volume 1333 || Black Phosphorus Based Photodetectors
摘要： The layered two-dimensional (2D) black phosphorus (BP) has found significant applications in nanoelectronics and nanophotonics. In particular, it has been proven as a promising material for photodetectors due to its narrow direct bandgap ranging from 0.3 eV to 2 eV, high carrier mobility, modulation capability, and polarization sensitivity. The modulation capability of BP based photodetector is achieved by gate control using field effect transistor structure. Homojunction and heterojunction have been demonstrated to suppress dark current while enhancing carrier collection efficiency. Plasmonic effect and avalanche breakdown are exploited to boost the responsivity further. To extend the detection wavelength of BP, electric field modulation and arsenide doping are investigated, leading to a wide detection wavelength up to 8 μm. Owing to the ease of integrating BP with diverse substrates due to BP’s 2D nature, waveguide-integrated BP based photodetectors are realized in the near-infrared (NIR) for telecommnunication applications and in the mid-infrared (MIR) for on-chip sensing applications. High speed and high responsivity can be achieved by optimizing the device design. Despite that the mechanical robustness of BP on waveguide remains challenging, nevertheless, wafer-level growth of BP is highly desirable to realize scalable integration for mass production.
关键词： near-infrared,black phosphorus,waveguide-integrated,nanoelectronics,nanophotonics,photodetectors,mid-infrared
更新于2025-09-12 10:27:22
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Ultraviolet photodetectors based on doped ZnO films
摘要： In this paper, we report the realization of ultraviolet (UV) photodetector based on doped ZnO films. The ZnO p-n junction was fabricated on indium tin oxide (ITO) coated glass, which consists of n-type and p-type layers based on Ga-doped (2 at.%) and N-doped (20 at.%) ZnO films, respectively. The current-voltage (IV) characteristics, photosensitivity, photoresponsitivity, and photocurrent gain were derived to determine the performance of the device. At 5 V reverse bias, the ZnO-based UV photodetector exhibits photosensitivity of 10.9, photoresponsivity of 2.1 × 10-2 AW-1, and photoconductive gain of 7.2 × 10-2.
关键词： ultraviolet photodetectors,sol-gel spin coating,p-n junction,doped ZnO films
更新于2025-09-12 10:27:22