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Characteristics of GeSn-based multiple quantum well heterojunction phototransistors: a simulation-based analysis
摘要： Introduction of multiple quantum wells (MQWs) is an efficient way to enhance the light absorption capability in phototransistors. Direct band gap Ge1?xSnx alloy (x?>?0.08) having large absorption coefficient is an attractive material for heterojunction phototransistors (HPTs) compatible with CMOS platform. In this work, simulations are employed to obtain current gain, responsivity and collector current characteristics of Ge/GeSn/Ge HPTs with incorporation of MQWs (Ge0.87Sn0.13/Ge0.83Sn0.17) in the base region. The performances of bulk, single quantum well and MQW HPT structures are examined and compared. Best performance is shown by HPTs having MQW structure over a wide range of base emitter voltage.
关键词： simulation,current gain,heterojunction phototransistors,responsivity,GeSn,multiple quantum wells
更新于2025-09-23 15:21:21
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[IEEE 2018 23rd Opto-Electronics and Communications Conference (OECC) - Jeju Island, Korea (South) (2018.7.2-2018.7.6)] 2018 23rd Opto-Electronics and Communications Conference (OECC) - 2.8?μm infrared photodetectors based on PbSe colloidal quantum dot films
摘要： In this study, we synthesized monodisperse and high purity PbSe CQDs and then demonstrated the photodetectors working at different wavelengths up to 2.8 μm. Colloidal quantum dots (CQDs) have been studied extensively due to their attractive optoelectronic properties such as high luminescence efficiency, large dipole moment, strong light absorption, good photo-stability, and multiple electron hole pair generation. More importantly, the strong quantum confinement effect allows us to tailor the energy band gap of these materials by controlling their size in a cost-effective wet chemical synthesis. These advantages bring CdSe-based CQDs to a competitive market of lighting and display technology today. The research on lead based chalcogenide (PbTe, PbS, and PbSe) CQDs for infrared applications has also received much scientific and technological attention because of the possibility to tune the bandgap in the infrared wavelength range. Among lead based chalcogenide family, lead selenide (PbSe) CQDs have received more attention in not only photodetectors but also many infrared optoelectronic applications like solar cells, light emitting diodes, etc [1-4]. In the present work, we report about high performance photodetectors at a broad spectral range, for the first time, up to 2.8 μm based on our high quality, monodisperse PbSe CQDs. We deposited thin films of synthesized PbSe CQDs on the patterned interdigitated platinum electrodes by a drop casting method to create photodetectors. These photodetectors with different thicknesses of the PbSe CQD film were studied and optimized in detail for the best performance. The photocurrent responses were recorded as a function of bias voltage using infrared LED illuminations with wavelengths of up to 2.8 μm.
关键词： infrared photodetectors,detectivity,responsivity,PbSe colloidal quantum dots,photocurrent
更新于2025-09-23 15:21:01
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Surface Engineered Hybrid Corea??Shell Sia??Nanowires for Efficient and Stable Broadband Photodetectors
摘要： Silicon nanostructures have gained intensive interest to develop broadband photodetectors at a large-scale due to their excellent electronic properties. Herein, Si-nanowires (SiNWs) decorated with reduced graphene oxide:carbon quantum dots (rGO:CQDs) nanocomposite (NC), as core–shell heterojunction building blocks for broadband (ultraviolet (UV)–near infrared (NIR)) photodetectors (PDs), are demonstrated. The SiNWs and CQDs are synthesized by wet-chemical etching and facile pyrolysis methods, respectively. Photogenerated carriers are transported through rGO because of its high electron mobility and favorable band alignment with CQDs and Si. Further, to minimize the recombination of photogenerated carriers, and enhance the response in the visible region, plasmon-enhanced AuCQDs are incorporated in the shell matrix. The optimized heterostructure (rGO:AuCQDs/undoped CQDs/SiNWs) is sensitive to a broad wavelength range covering the UV to NIR (360 to 940 nm) region, manifests the excellent responsivity of 16 A W?1 at 360 nm, detectivity (D*) of 2.2 × 1013 Jones, and noise equivalent power as low as 2.8 fW Hz?1/2. The optimized PDs heterostructure demonstrates excellent air-stability after 8 days of illumination without any encapsulation or protective coating. The proposed simple, cost-effective, and Si-process-line compatible fabrication of Si-based PD device structure imposes a great promise for highly efficient and stable advanced futuristic optoelectronic devices.
关键词： core–shell heterostructure,detectivity,responsivity,broadband photodetectors,reduced graphene oxide,carbon quantum dots,Si nanowires
更新于2025-09-23 15:21:01
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All organics thin film flexible photodetector based on C<sub>60</sub> modified PEDOT:PSS
摘要： In organic electronics, the use of self-assembled monolayer dielectric functional groups is considered an effective surface modification strategy that can significantly improve device performance. A flexible polymer (PEDOT:PSS) photodetector on the substrate polyimide (PI) with broadband response (450 nm~980 nm) and high response (0.56 A/W) is reported, which is superimposed on the surface by small molecule (C60) thermal evaporation. In addition, the planeness of organic semiconductor and the overall performance of organic thin film photodetector can be improved significantly by using small molecule modified polymer thin film, the response of small molecule modified organic device is improved by an order of magnitude, which provides a guarantee for better application of organic thin films in circuits. Moreover, the device has strong flexibility stability performance, which can meet the requirements of flexible stability of future photoelectric devices.
关键词： organic thin film,high responsivity,broadband response,Photodetector,flexibility
更新于2025-09-23 15:21:01
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Mid-Wavelength Infrared Responsivity of Colloidal Quantum Dot/Organic Hybrid Photodetectors
摘要： Colloidal quantum dot/organic hybrid materials approach offer a path toward engineering solution-processed photodetectors with extended spectral responsivity in the infrared. We demonstrate this approach in the technologically important thermal infrared region of mid-wavelength infrared, utilizing a solution blend of Ag2Se colloidal quantum dots and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We report on the device fabrication and their room temperature optical, electrical, and optoelectronic properties. At room temperature, a responsivity of 0.2 mA/W was measured under 5 μm irradiation and 5 V bias. The new hybrid optoelectronic film demonstrated the advantage of cost-effectiveness and greater fabrication versatility than the single crystal or epitaxial semiconductors that comprise today’s infrared technologies.
关键词： Colloidal quantum dots,Photodetectors,Mid-wavelength infrared,Organic hybrid,Responsivity
更新于2025-09-23 15:21:01
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High Responsivity Visible Blind Pd/Al2O3/MoS2/ITO MISM UV Photodetector
摘要： In the present paper, Pd/Al2O3/MoS2/ITO MISM UV photodetector structure is proposed and analyzed. For the proposed photodetector, responsivity is 488 A/W, detectivity is 8.22×1013Jones and external quantum efficiency (EQE) is 1.9×105%, at wavelength 308nm, 1V bias and light intensity 13.6μW/cm2. Thus, proposed MISM photodetector device gives significant performance improvement over other UV photodetectors.
关键词： Molybdenum di-sulphide (MoS2),Responsivity,Photodetector,X-ray diffraction (XRD)
更新于2025-09-23 15:21:01
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[IEEE 2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS) - Vancouver, BC, Canada (2020.1.18-2020.1.22)] 2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS) - Monolithic Integration of Plasmonic Meta-Material Absorber with CMOS-MEMs Infrared Sensor for Responsivity Enhancement and Human Detection Application
摘要： This study integrates monolithically a metal-insulator-metal-based plasmonic metamaterial absorber (PMA) with a thermoelectric (TE) infrared (IR) sensor using standard TSMC CMOS platform. The proposed design extends the strip-via releasing hole structure in [1] to further integrate MIM absorber with TE IR sensor. Such design exhibits three merits: (1) the line width requirement of MIM absorber is achieved by CMOS process, (2) the absorption peaks of MIM absorbers can be modulated by pattern designs in the epsilon-near-pole region, and (3) the MIM absorbers can be designed to broaden the absorption spectrum of IR sensor. In application, the absorption spectrum of IR sensor is designed within 8-14μm in this study for human detection application. Measurement result demonstrates the integration of MIM absorber and IR sensor can achieve 21% improvement and the measured absorption spectrum matches with simulation.
关键词： CMOS-MEMS,human detection,thermoelectric infrared sensor,responsivity enhancement,plasmonic metamaterial absorber
更新于2025-09-23 15:21:01
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Measurement setup for differential spectral responsivity of solar cells
摘要： We have developed a setup for measuring differential spectral responsivities of unifacial and bifacial solar cells under bias light conditions. The setup uses 30 high-brightness LEDs for generating a quasi-monochromatic light source covering the wavelength range 290–1300 nm. Halogen lamps are used to generate bias-lighting conditions up to the irradiance level of 1000 W/m2. The setup has been fully characterized for spectral irradiances and spatial uniformities of all light sources. Validation measurements carried out using a reference cell of 2 × 2 cm2 area from Fraunhofer ISE demonstrated an agreement better than 2% over the wavelength range of 425–940 nm, with an expanded uncertainty of 2.6%. In the UV and IR regions, the discrepancies are higher but still within estimated uncertainties. The setup is also tested in measuring spectral responsivities of large 15 × 15 cm2 bifacial solar cells. The associated problems are discussed.
关键词： Radiometry,Bifacial,Solar cell,Spectral responsivity,Electricity,Efficacy
更新于2025-09-23 15:21:01
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Surface modification of AlN using organic molecular layer for improved deep UV photodetector performance
摘要： Direct wide bandgap of 6.2 eV, high temperature robustness and radiation hardness make aluminum nitride (AlN) a preferable semiconductor for deep ultraviolet (UV) photodetection. However, the performance and reliability of AlN- based devices is adversely affected by a large density of surface states present in AlN. In this work, we have investigated the potential of a monolayer of organic molecules in passivating the surface states of AlN which improved the performance of AlN- based metal- semiconductor- metal (MSM) deep UV photodetectors. The organic molecules of Meso-5,10,15-triphenyl-20-(p-hydroxyphenyl)porphyrin Zn(II) complex (ZnTPP(OH)) were successfully adsorbed on AlN surface, forming a self- assembled monolayer (SAM). The molecular layer was characterized by contact angle measurement, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The surface modification of AlN effectively reduced dark current of the photodetector by ten times without degrading the magnitude of photo current, especially at low voltages. Photo to dark current ratio (PDCR) was enhanced from 930 to 7835 at -2V and the responsivity doubled from 0.3 mA/W to 0.6 mA/W at 5V. Moreover, the rise and fall times of the detector were found to decrease after the surface modification process. Our results suggest that SAM of porphyrin molecules effectively passivated the surface states in AlN which resulted in improved photodetector performance.
关键词： Dark current,PDCR,MSM UV photodetector,Surface states,SAM,Responsivity,Temporal response
更新于2025-09-23 15:19:57
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High-Performance Germanium Waveguide Photodetectors on Silicon
摘要： Germanium waveguide photodetectors with 4 ??m widths and various lengths are fabricated on silicon-on-insulator substrates by selective epitaxial growth. The dependence of the germanium layer length on the responsivity and bandwidth of the photodetectors is studied. The optimal length of the germanium layer to achieve high bandwidth is found to be approximately 8 ??m. For the 4 × 8 ??m2 photodetector, the dark current density is as low as 5 mA/cm2 at ?1 V. At a bias of ?1 V, the 1550 nm optical responsivity is as high as 0.82 A/W. Bandwidth as high as 29 GHz is obtained at ?4 V. Clear opened eye diagrams at 50 Gbits/s are demonstrated at 1550 nm.
关键词： responsivity,Germanium waveguide photodetectors,silicon-on-insulator substrates,selective epitaxial growth,bandwidth
更新于2025-09-23 15:19:57