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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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Mid-infrared dual-comb spectroscopy with room-temperature bi-functional interband cascade lasers and detectors
摘要： Interband cascade (IC) laser structures offer attractive potential for operation at room temperature as both broadband coherent sources of mid-infrared light and fast photodetectors. This makes the realization of extremely compact spectrometers on a monolithic platform possible, and even dual-comb spectroscopy (DCS) configurations. IC comb devices are perfect candidates for this configuration, since they develop near-THz-wide optical frequency comb spectra from a millimeter-sized cavity, using a multi-stage structure that can also function as a very fast photodetector. In this work, we leverage IC photodetectors with a gigahertz bandwidth to demonstrate a self-contained, free-running, room-temperature DCS system in the mid-infrared. The DCS system used detection by the same bi-functional IC device structure to measure 1,1-difluoroethane over (cid:2)600 GHz of optical coverage around 3.6 mm. These results show that the IC platform is suitable for full integration as a broadband, high-resolution on-chip spectrometer in a future chemical sensing system.
关键词： mid-infrared,photodetectors,dual-comb spectroscopy,interband cascade lasers,room-temperature
更新于2025-09-23 15:21:01
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A comparison of mechanisms for improving dark current characteristics in barrier infrared photodetectors
摘要： The dark current characteristics in InAs/GaSb type-II superlattice (SL) barrier infrared photodetectors are theoretically investigated using the drift-diffusion-based device simulator. It is shown that both structures can effectively reduce the dark current compared to the p-i-n photodiode without barrier, and the dependence on the barrier doping density are discussed in detail. There exists an optimum doping density to minimize the dark current in active region (n type), for which two different engineered structures, i.e., called pBn and nBn, are evaluated.
关键词： dark current,pBn,InAs/GaSb type-II superlattice,barrier infrared photodetectors,nBn
更新于2025-09-23 15:19:57
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Composition and size controlled I-V-VI semiconductor nanocrystals
摘要： Non-isovalent ternary and quaternary semiconductors (i.e., having two or more cations with different valence) have unique structural and electronic properties that are leveraged in photovoltaic, thermoelectric, and phase-change memory devices. Making these complex semiconductors in the form of colloidal nanocrystals imparts size-dependent properties and solution processability. Here, we present results on I‐V‐VI group colloidal nanocrystals. We focus on achieving sub-10 nm sizes for a wide range of I-V-VI selenide nanocrystals, including AgSbSe2, AgSb2Se3, CuSbSe2, Cu3SbSe4, AgBiSe2, and CuBiSe2. To highlight one possible application for these I-V-VI colloidal nanomaterials, we analyze the optical absorption and show that through composition and size control, this class of materials offers bandgaps in the mid- to near-IR. Absorption coefficients of AgSbSe2, CuSbSe2, and Cu3SbSe4 nanocrystals are on par with or higher than the well-studied PbS nanocrystals highlighting their potential for devices such as solar cells, (mid-)infrared photodetectors, and near-infrared bio-imaging systems.
关键词： solar cells,optical absorption,bio-imaging systems,colloidal nanocrystals,infrared photodetectors,mid- to near-IR,I-V-VI semiconductor nanocrystals,bandgaps
更新于2025-09-23 15:19:57
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InGaAs/graphene infrared photodetectors with enhanced responsivity
摘要： High responsivity is a vital aim of photodetectors research. Based on the photogating effect, ultra-high responsivity can be realized by combining the high mobility of graphene and strong light absorption of other materials. Due to long carrier lifetime and low mobility, quantum dots(QDs) are usually used to form hybrid photodetectors with graphene. However, hybrid photodetectors of graphene with materials possessing higher mobility are rarely studied at present. In this paper, the hybrid photodetector of graphene and InGaAs is studied. We fabricated and measured pure InGaAs photodetectors, hybrid photodetectors of the whole graphene on InGaAs surface and hybrid photodetectors of graphene nanoribbons(GNRs) on InGaAs surface. It is found that, compared to pure InGaAs photodetectors, the responsivity of the whole graphene on InGaAs surface devices increases by 14.7 times, which is 7.66 A W?1, and the response time is twice faster. We also found that the negative back voltage can increase the photocurrent by modulating the Fermi energy of graphene and barrier height of the hybrid photodetectors. The illuminated area effect on various devices area was discussed in this study. In terms of theoretical mechanization, as high mobility materials, both graphene and InGaAs could generate and transport carriers in this hybrid photodetector under optical illumination. The photoexcited holes in InGaAs enter graphene while the photoexcited electrons in graphene enter InGaAs due to the built-in ?eld, which leads to a charge build-up on both sides of the junction and a strong photogating effect on the channel conductance. The results of this study are of novel signi?cance for the development of infrared detectors based on graphene.
关键词： infrared photodetectors,responsivity,graphene,InGaAs
更新于2025-09-19 17:13:59
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In-Situ Tailoring of Vertically Coupled InAs p-i-p Quantum-Dot Infrared Photodetectors: Toward Homogeneous Dot Size Distribution and Minimization of Ina??Ga Intermixing
摘要： The authors report a detailed analysis of an epitaxial growth technique for Indium Arsenide (InAs) Quantum-dot infrared photodetectors to circumvent the detrimental effects arising from the progressively increasing dot-size in vertically coupled heterostructures. Constant overgrowth percentage of the vertically coupled dot-layers has been achieved with the implementation of the growth strategy, which has been validated by cross-sectional transmission electron microscopy (X-TEM) images of the samples. The optical characteristics of these samples have been analyzed through photoluminescence spectroscopy and photoluminescence excitation spectroscopy (PL and PLE) measurements which show longer wavelength response and reduced full width at half-maxima (FWHM) upon implementation of the growth strategy. X-TEM, in-plane and out-of-plane high resolution X-ray diffraction (HR-XRD) measurements suggest morphological improvement upon implementation of the growth strategy, with a reduction in the Indium desorption and lowering of defects and dislocation densities. Excellent correlation has been found between the different experimental results and also their theoretical simulations. The fabricated single-pixel photodetectors at low temperature (T=14K) show a broad response extending up to the MWIR region (~4.5μm) for one of the samples. Also, a strong spectral response in the SWIR region is obtained even at room temperature (T=300K). The highest responsivity (Rp) and specific detectivity (D*) values obtained are 166.17 A/W and 8.39 x 1010 cmHz1/2W-1 at a bias of 5V and 300K temperature.
关键词： p-i-p infrared photodetectors,InAs Quantum Dots,MBE growth strategy,homogenous dot size distribution,room temperature spectral response,In-Ga inter-diffusion
更新于2025-09-19 17:13:59
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Role of nanowire length on the performance of self-driven NIR Photodetector based on mono/bi-layer graphene (camphor)/Si-Nanowire Schottky junction
摘要： In this article, we have demonstrated a solid carbon source such as camphor as a natural precursor to synthesize a large area mono/bi-layer graphene (MLG) sheet to fabricate nanowire junction based near infrared photodetectors (NIRPDs). In order to increase the surface-to-volume ratio, we have developed Si-nanowire arrays (SiNWAs) of varying lengths by etching up to 2V with a fast rise and decay time of 34/13 ms. A tremendous enhancement has been witnessed from 36 μA/W to 22 mA/W in the responsivity at 0V for MLG/30 min SiNWAs than planar Si. Then, the camphor based MLG/Si and MLG/SiNWAs schottky junction photodetectors have been fabricated to achieve efficient response with self-driven properties in the near infrared (NIR) regime. Due to a balance between light absorption capability and surface recombination centres, devices having SiNWAs obtained by etching for 30 min shows a better photoresponse, sensitivity and detectivity. Fabricated NIRPDs can also be functioned as self-driven device which are highly responsive and very stable at low optical power signals indicating an important development of self-driven NIRPDs based on camphor based MLG for future optoelectronic devices.
关键词： Si nanowire arrays,Graphene,Camphor,Responsivity and near infrared photodetectors.
更新于2025-09-19 17:13:59
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High Sensitivity Hybrid PbS CQD-TMDC Photodetectors up to 2 μm
摘要： Recent approaches to develop infrared photodetectors characterized by high sensitivities, broadband spectral coverage, easy integration with silicon electronics, and low cost have been based on hybrid structures of transition metal dichalcogenides (TMDCs) and PbS colloidal quantum dots (CQDs). However, to date, such photodetectors have been reported with high sensitivity up to 1.5 μm. Here we extend the spectral coverage of this technology toward 2 μm, demonstrating for the ?rst time compelling performance with responsivities 1400 A/W at 1.8 μm with 1 V bias and detectivities as high as 1012 Jones at room temperature. To do this, we studied two TMDC materials as a carrier transport layer, tungsten disul?de (WS2), and molybdenum disul?de (MoS2) and demonstrate that WS2-based hybrid photodetectors outperform those of MoS2 due to a more adequate band alignment that favors carrier transfer from the CQDs.
关键词： quantum dots,tungsten sul?de,infrared photodetectors,lead sul?de,molybdenum sul?de,two-dimensional materials
更新于2025-09-16 10:30:52
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Infrared plasmonic photodetectors: the emergence of high photon yield toroidal metadevices
摘要： Plasmon excitations in metallic nanostructures can decay directly into dynamic electronehole pairs, exploitable for photocurrent generation. This approach has extensively been employed to develop nanoplasmonic light-sensing devices with signi?cant responsivity and quantum ef?ciency. Among the devices, infrared plasmonic photodetectors have gained particular interest for their wide range of technological applications, including spectroscopy, biosensing, and surveillance. This Review discusses the fundamentals, recent advances, and trending mechanisms in the understanding and applications of plasmon-enhanced photocurrent generation in nanostructures across the infrared spectrum. By highlighting and comparing the developed techniques, we demonstrate the newly introduced directions toward achieving high photon yield infrared plasmonic photodetection tools. As a promising concept in modern metaphotonics, we present the emergence of toroidal meta-atoms as plasmon-induced carrier generators with unconventionally exquisite properties for designing advanced, rapid, and next-generation plasmonic photodetectors with signi?cantly high responsivity and photocurrent.
关键词： Photocurrent,Plasmonics,Infrared photodetectors,Plasmon-induced carrier generation,Toroidal photodetectors
更新于2025-09-12 10:27:22
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Long Wavelength Lead Sulfide Quantum Dots Sensing up to 2600 nm for Short Wavelength Infrared Photodetectors
摘要： Lead sulfide nanoparticles (PbS NPs) are used in the short wavelength infrared (SWIR) photodetectors because of their excellent photosensitivity, bandgap tunability, and solution processability. It has been a challenge to synthesize high quality PbS NPs with an absorption peak beyond 2000 nm. In this work, using PbS seed crystals with an absorption peak at 1960 nm, we report a successful synthesis of very large mono-dispersed PbS NPs having a diameter up to 16 nm by multiple injections. The resulting NPs have an absorption peak over 2500 nm with a small full-width-at-half-maximum (FWHM) of 24 meV. To demonstrate the applications of such large QDs, broadband heterojunction photodetectors are fabricated with the large PbS QDs of an absorption peak at 2100 nm. The resulting devices have an EQE of 25% (over 50% IQE) at 2100 nm corresponding to a responsivity of 0.385 A/W, and an EQE ~60% in the visible range.
关键词： sensing up to 2600 nm,infrared photodetectors,Lead sulfide quantum dots,multiple injections,mono-dispersity
更新于2025-09-12 10:27:22