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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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High-Performance p-BP/n-PdSe2 Near-Infrared Photodiode with Fast and Gate-Tunable Photoresponse
摘要： Van der Waals heterostructures composed of transition metal dichalcogenide (TMDs) materials have become a remarkable compact system that could offer an innovative architecture for advanced engineering in high-performance energy-harvesting and optoelectronic devices. Here, we report a novel van der Waals (vdW) TMDs heterojunction photo-diode composed of black phosphorus (p-BP) and palladium diselenide (n-PdSe2) which establish a high and tunable rectification and photoresponsivity. A high rectification up to ≈ 7.1 × 105 is achieved which is successfully tuned by employing the back gate voltage to the heterostructure devices. Besides, the device significantly shows the high and gate-controlled photoresponsivity of ?? = 9.6 × 105 ?? ?? ―1, 4.53 × 105 ???? ―1 and 1.63 × 105 ???? ―1 under the influence of light of different wavelengths (?? = 532, 1064 and 1310 nm) in visible and near-infrared regions respectively due to interlayer optical transition and low Schottky. The device also demonstrates extraordinary values of detectivity (?? = 5.8 × 1013 Jones) and external quantum efficiency (?????? ≈ 9.4 × 106), which are an order of magnitude higher than the currently reported values. The effective enhancement of photovoltaic characteristics in visible and infrared regions of this TMDs heterostructure based system has a huge potential in the field of optoelectronics to realize high-performance infrared photodetectors.
关键词： rectification,palladium diselenide,detectivity,photoresponsivity,transition metal dichalcogenide materials,near-infrared
更新于2025-09-23 15:21:01
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Ultrahigh-Speed Mid-Infrared Photodetectors With 2-D Electron Gas in a CdTe/PbTe Heterojunction
摘要： A CdTe/PbTe heterojunction (HJ) yields two-dimensional electron gas (2DEG) with a high electron density and mobility. Ultrahigh-speed and room-temperature operating mid-infrared photodetectors are developed with the 2DEG. The photoresponse of the detectors originates from the intrinsic response of PbTe by virtue of the conduction-band and valence-band alignment of the HJ. The extremely short rise and decay photoresponse time demonstrate a major advantage of the 2DEG. At λ = 3.0 μm and a bias voltage of 100 mV, the responsivity and detectivity reach 0.94 A/W and 2 × 1010 Jones, respectively. The excellent performance of the detectors renders promising applications in novel mid-infrared frequency detection systems.
关键词： two-dimensional electron gas (2DEG),room-temperature (RT) operation,ultrahigh-speed response,Detectivity,mid-infrared detector
更新于2025-09-23 15:21:01
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A Selfa??Powered Higha??Performance UV Photodetector Based on Corea??Shell GaN/MoO <sub/>3a??</sub><i> <sub/>x</sub></i> Nanorod Array Heterojunction
摘要： Self-powered UV photodetectors are highly desirable for applications in space communications and environmental monitoring. However, most self-powered UV photodetectors exhibit unimpressive performance in weak signal detection. Herein, a self-powered UV photodetector based on the core–shell GaN/MoO3–x nanorod array (NRA) heterojunction system is demonstrated. Homogeneous MoO3–x layers are deposited on GaN NRAs by a simple one-step physical vapor deposition method. The photodetector device shows an ultrahigh specific detectivity of 2.7 × 1015 Jones at 355 nm without any power supply. Further analyses reveal a responsivity of 160 A W?1 and a high UV–vis rejection ratio (R355 nm/R400 nm) of 2.0 × 104 under zero bias. The self-powered device also has a fast response speed with a rise/fall time of 73/90 μs. As a result, the self-powered photodetector, featuring ultrahigh detectivity and responsivity along with fast response, exhibits great potential for applications in next-generation UV detection. The core–shell NRA structure heterojunction design provides a valuable direction for realizing nanoscale self-powered UV photodetectors.
关键词： core–shell nanorod arrays,UV photodetectors,ultrahigh detectivity,self-powered devices
更新于2025-09-23 15:21:01
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High performance Zn-diffused planar mid-wavelength infrared type-II InAs/InAs <sub/>1a??x</sub> Sb <sub/>x</sub> superlattice photodetector by MOCVD
摘要： We report a Zn-diffused planar mid-wavelength infrared photodetector based on type-II InAs/InAs1?xSbx superlattices. Both the superlattice growth and Zn diffusion were performed in a metal-organic chemical vapor deposition system. At 77 K, the photodetector exhibits a peak responsivity of 0.70 A/W at 3.65 μm, corresponding to a quantum efficiency of 24% at zero bias without anti-reflection coating, with a 50% cutoff wavelength of 4.28 μm. With an R0A value of 3.2 × 105 Ω cm2 and a dark current density of 9.6 × 10?8 A/cm2 under an applied bias of ?20 mV at 77 K, the photodetector exhibits a specific detectivity of 2.9 × 1012 cm Hz1/2/W. At 150 K, the photodetector exhibits a dark current density of 9.1 × 10?6 A/cm2 and a quantum efficiency of 25%, resulting in a detectivity of 3.4 × 1011 cm Hz1/2/W.
关键词： specific detectivity,metal-organic chemical vapor deposition,type-II InAs/InAs1?xSbx superlattices,quantum efficiency,Zn-diffused planar mid-wavelength infrared photodetector
更新于2025-09-23 15:19:57
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High Sensitivity Visible-Near Infrared Organic Photodetector Based on Non-fullerene Acceptor
摘要： Highly sensitive solution-processed organic photodetectors (OPDs) with a broadband response ranging from visible to near infrared (NIR) and excellent overall device performance are demonstrated. The OPDs were fabricated from a blend consisting of a wide bandgap polymer donor and a newly developed fused octacylic small-molecule electron acceptor with acceptor–donor–acceptor structure, which shows relatively high and balanced hole/electron mobility and allow for thicker photoactive layer (~300 nm). In conjunction with the use of an optimized inverted device structure, the dark current density of the OPDs was suppressed to an ultralow level of (8.3±5.5)×10-10A cm-2 at bias of –1 V and the capability to directly weak light intensity is down to 0.24 pW cm?2, both are among the lowest reported values for OPDs. Owing to the low shot noise enabled by the inverted structure and the low thermal noise due to the high shunt resistance of the device, the obtained OPDs shows spectrally flat photoresponse in the range of 350–950 nm (UV-Vis-NIR) and a maximal specific detectivity (D*) of (2.1±0.1)×1013 Jones at 800–900 nm, which is among the best results of NIR OPDs reported to date and represents a highly sensitive photodetector for weak optical signal detection. Besides, the OPDs shows a wide bandwidth of 30 kHz, fast temporal response time around 12 us ~14 us and a large linear dynamic range of 106 dB.
关键词： dark current density,specific detectivity,non-fullerene acceptors,weak optical signal detection,organic photodetectors
更新于2025-09-23 15:19:57
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Growth of monolayer and bilayer MoS2 through the solution precursor for high-performance photodetectors
摘要： Various studies suggest that the performances of TMDs are largely thickness dependent. In this paper, we develop a chemical vapor deposition method to synthesis monolayer and bilayer MoS2 flakes with a solution precursor. The MoS2 phototransistors were prepared to investigate their optoelectronic performance. The MoS2 photodetectors exhibit high detectivity of 2.44×1011 and a fast response/recovery time of 97 ms/291 ms. The photoresponsivity of bilayer MoS2 flakes was found up to 7160 A W?1. Our research will pave a pathway to control the layer numbers of other TMDs nanostructures, expand the application of high performance 2D materials.
关键词： Fast response/recovery time,Chemical vapor deposition,H8MoN2O4,Liquid precursor,Control of the layer numbers,High detectivity
更新于2025-09-23 15:19:57
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SbSI microrod based flexible photodetectors
摘要： In this paper, SbSI microrods is prepared by using a simple hydrothermal method via sulfur powder as sulfur source. The as-synthesized SbSI microrods with sulfur as sulfur powder source has better flexibility than that of SbSI with thiourea as sulfur source due to decreasing force constant between Sb and S atom. SbSI microrod based flexible photodetectors exhibit higher specific detectivity of up to 5.43×1010 Jones, fast response speed (rise time and fall time of 61 ms and 128 ms, respectively) and also show low dark current less than 50 pA. Especially, the photoresponse performance of the SbSI microrod based flexible photodetectors are almost unchanged after different bending curvatures and bending times more than 2000 times.
关键词： higher specific detectivity,fast response speed,SbSI microrods,flexible photodetector
更新于2025-09-23 15:19:57
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Bifunctional Etalon-Electrode to Realize High Performance Color Filter Free Image Sensor
摘要： Organic photodiodes (OPDs), based on organic semiconductors with high absorption coefficients for visible light, are emerging as potential candidates for replacing silicon photodiodes in image sensors, particularly due to the possibility of realizing a thin thickness and exclusion of color filters, both of which can contribute to a dramatically enhanced degree of integration for image sensors. Despite years of research, techniques have not yet been developed that allow the OPD itself to have color selectivity while maintaining a thin (<1 μm) OPD thickness, in combination with a sufficiently high detectivity (>1012 cm?Hz0.5/W). To solve this issue, we introduce a concept of 'etalon-electrode', which can perform the function of electrode, and simultaneously the function of selective wavelength transparency. A strategically designed OPD architecture consisting of an etalon-electrode, a panchromatic organic active layer, and a counter electrode displays well-defined narrowband R-/G-/B-selective detectivity spectra depending on precision-adjusted thickness composition of the etalon-electrode. While a thin thickness of OPD is preserved at less than 800 nm including electrodes, active layer and other buffer layers for all R-/G-/B-selective OPDs, high average detectivity values over 1012 cm?Hz0.5/W are demonstrated. Furthermore, the characteristic of imparting color selectivity by the etalon-electrode enables a more facile full color patterning, such that a prototype of a 10×10 image sensor with a pixel pitch of 500 μm is realized, resulting in accurate picturing of a well-defined full color image.
关键词： high detectivity,organic photodiodes,etalon-electrodes,full-color imaging,color filter free,image sensor,wavelength selectivity
更新于2025-09-19 17:15:36