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This paper presents a 2300 nm wavelength photodetector which comprises a spin‐deposited colloidal HgTe quantum dot (QD) film on a metal‐insulator‐metal (MIM) plasmonic waveguide. This photodetector is an integrated device based on the complementary metal‐oxide‐semiconductor compatible silicon‐on‐insulator platform. The device employs input and output silicon waveguide grating couplers, and HgTe QDs are used as the infrared photosensing material. Infrared light is coupled to the strongly confined MIM waveguide mode, which shrinks the device footprint and improves the light detection efficiency simultaneously. A room temperature responsivity of 23 mA W−1 and a noise‐equivalent power of 8.7 × 10−11 W Hz−1/2 at 2300 nm wavelength are achieved by the photodetector at 2.14 W mm−2 (measured at the input to the plasmonic waveguide) with a device footprint of 15 µm × 0.35 µm. The light intensity–dependent photocurrent, the current noise spectral density, and the 3 dB operation bandwidth are all characterized. The charge transfer properties of the organic HgTe QD films are further analyzed based on field effect transistor measurements.  相似文献   

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A method of wet‐transferring a densely packed colloidal quantum dot (CQD) film is reported herein. Layers of poly(vinyl alcohol) (sacrificial layer) and poly(methyl methacrylate) (temporary mechanical support) are spin‐coated below and above the CQD film, respectively; the two layers are eventually removed, resulting in a single CQD film on an alien substrate. CQD films as large as 1 cm × 1 cm are transferred to any substrate, including flexible and prepatterned ones, with very little mechanical or optical damage. The wet‐transfer method can be repeated to form a CQD heterostructure. A CQD distributed feedback (DFB) laser is also demonstrated by transferring a thick CdSe‐based CQD layer (for both optical gain and waveguiding) on top of a surface grating structure. The resultant CQD structure exhibits a single‐mode DFB lasing action, with a high spontaneous emission factor (β ≈ 10−3), owing to a strong vertical mode confinement and smooth surface morphologies on both sides of the CQD waveguide layer.  相似文献   

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采用磁控共溅射结合快速光热退火技术在单晶硅和石英衬底上制备了含硅量子点的周期性梯度富硅SiNx薄膜(梯度薄膜)和单层富硅SiNx薄膜(单层薄膜)。采用Raman光谱、掠入射X射线衍射(GIXRD)、透射电子显微镜(TEM)、傅里叶变换红外(FTIR)光谱和光致发光(PL)光谱分析了薄膜的结构特性、键合特性和发光特性。Raman光谱、GIXRD和TEM结果表明, 梯度薄膜和单层薄膜中的硅量子点晶化率分别为41.7%和39.2%; 梯度薄膜的硅量子点密度是单层薄膜的5.4倍。FTIR光谱结果显示两种薄膜均为富硅氮化硅薄膜, 梯度薄膜的硅含量小于单层薄膜。PL光谱结果表明梯度薄膜中的辐射复合缺陷少于单层薄膜。  相似文献   

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By virtue of the well‐developed micro‐ and nanofabrication technologies and rapidly progressing surface functionalization strategies, silicon‐based devices have been widely recognized as a highly promising platform for the next‐generation lab‐on‐a‐chip bioanalytical systems with a great potential for point‐of‐care medical diagnostics. Herein, an overview of the latest advances in silicon‐based integrated optofluidic label‐free biosensing technologies relying on the efficient interactions between the evanescent light field at the functionalized surface and specifically bound analytes is presented. State‐of‐the‐art technologies demonstrating label‐free evanescent wave‐based biomarker detection mainly encompass three device configurations, including on‐chip waveguide‐based interferometers, microring resonators, and photonic‐crystal‐based cavities. Moreover, up‐to‐date strategies for elevating the sensitivities and also simplifying the sensing processes are discussed. Emerging laboratory prototypes with advanced integration and packaging schemes incorporating automatic microfluidic components or on‐chip optoelectronic devices lead to one significant step forward in real applications of decentralized diagnostics. Besides, particular attention is paid to currently commercialized label‐free optical bioanalytical models on the market. Finally, the prospects are elaborated with several research routes toward chip‐scale, low‐cost, highly sensitive, multi‐functional, and user‐friendly bioanalytical systems benefiting to global healthcare.  相似文献   

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Antifreeze proteins (AFPs), a type of high‐efficiency but expensive and often unstable biological antifreeze, have stimulated substantial interest in the search for synthetic mimics. However, only a few reported AFP mimics display thermal hysteresis, and general criteria for the design of AFP mimics remain unknown. Herein, oxidized quasi‐carbon nitride quantum dots (OQCNs) are synthesized through an up‐scalable bottom‐up approach. They exhibit thermal‐hysteresis activity, an ice‐crystal shaping effect, and activity on ice‐recrystallization inhibition. In the cryopreservation of sheep red blood cells, OQCNs improve cell recovery to more than twice that obtained by using a commercial cryoprotectant (hydroxyethyl starch) without the addition of any organic solvents. It is shown experimentally that OQCNs preferably bind onto the ice‐crystal surface, which leads to the inhibition of ice‐crystal growth due to the Kelvin effect. Further analysis reveals that the match of the distance between two neighboring tertiary N atoms on OQCNs with the repeated spacing of O atoms along the c‐axis on the primary prism plane of ice lattice is critical for OQCNs to bind preferentially on ice crystals. Here, the application of graphitic carbon nitride derivatives for cryopreservation is reported for the first time.  相似文献   

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Advanced silicon photonic technologies enable integrated optical sensing and communication (IOSAC) in real time for the emerging application requirements of simultaneous sensing and communication for next-generation networks. Herein, an IOSAC system is proposed and demonstrated on the silicon nitride (Si3N4) photonics platform. The IOSAC devices leveraging microring resonators excel in real-time monitoring of analyte fluctuations and efficiently transmit this data to the terminal, positioning them as viable alternatives to bulk optics in applications that demand both high precision and speed. By directly integrating Si3N4 ring resonators with optical communication networks, simultaneous sensing and optical communication are demonstrated by an optical signal transmission experimental system using especially filtering amplified spontaneous emission spectra. The refractive index (RI) sensing ring with a sensitivity of 172 nm RIU−1, a figure of merit (FOM) of 1220, and a detection limit (DL) of 8.2 × 10−6 RIU is demonstrated. Simultaneously, the 1.25 Gbps optical on-off-keying (OOK) signal is transmitted at the concentration of different NaCl solutions, indicating the bit-error-ratio (BER) decreases with the increase in concentration. The novel IOSAC technology shows the potential to realize high-performance simultaneous biosensing and communication in real time and further accelerate the development of IoT and 6G networks.  相似文献   

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Optical readout within microfluidic chips is a bottleneck limiting their industrial development. The integration of lasers operating in the visible range within a microfluidic platform is crucial for enabling in situ optical measurements in lab‐on‐a‐chip applications. In principle, microstructured single‐crystal silicon is an excellent optofluidic platform, which allows integration of microfluidic channels together with optical circuits including micro‐optics, waveguides, and resonant cavities. However, the silicon absorption below 1.1 µm is a fundamental limit that prohibits the use of silicon‐based microcavities as the feedback element for visible lasers and restricts their use to the infrared only. In this work, an ultra‐wide band silicon cavity enabled by two deeply etched hollow‐core planar waveguides is demonstrated. The proposed microcavity shows a broad bandwidth extending from 500 to 1600 nm with quality factors up to 2067. A tubular microfluidic channel is inserted between the mirrors of the optofluidic cavity. The microfluidic channel is filled with Rhodamine 6G (R6G) at 20 µL min−1 flow rate allowing successful demonstration of lasing on silicon at 562.4 nm. The laser beam propagates in‐plane (along the chip surface) and is handled with monolithically integrated input/output optical fiber grooves. This provides a unique silicon platform integrating hollow core optofluidic channels together with optical cavities, which is suitable for implementing optical readout in lab‐on‐a‐chip devices.  相似文献   

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Developing low‐cost photovoltaic absorbers that can harvest the short‐wave infrared (SWIR) part of the solar spectrum, which remains unharnessed by current Si‐based and perovskite photovoltaic technologies, is a prerequisite for making high‐efficiency, low‐cost tandem solar cells. Here, infrared PbS colloidal quantum dot (CQD) solar cells employing a hybrid inorganic–organic ligand exchange process that results in an external quantum efficiency of 80% at 1.35 µm are reported, leading to a short‐circuit current density of 34 mA cm?2 and a power conversion efficiency (PCE) up to 7.9%, which is a current record for SWIR CQD solar cells. When this cell is placed at the back of an MAPbI3 perovskite film, it delivers an extra 3.3% PCE by harnessing light beyond 750 nm.  相似文献   

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Colloidal quantum dots (CQDs) are nanoscale building blocks for bottom‐up fabrication of semiconducting solids with tailorable properties beyond the possibilities of bulk materials. Achieving ordered, macroscopic crystal‐like assemblies has been in the focus of researchers for years, since it would allow exploitation of the quantum‐confinement‐based electronic properties with tunable dimensionality. Lead‐chalcogenide CQDs show especially strong tendencies to self‐organize into 2D superlattices with micrometer‐scale order, making the array fabrication fairly simple. However, most studies concentrate on the fundamentals of the assembly process, and none have investigated the electronic properties and their dependence on the nanoscale structure induced by different ligands. Here, it is discussed how different chemical treatments on the initial superlattices affect the nanostructure, the optical, and the electronic‐transport properties. Transistors with average two‐terminal electron mobilities of 13 cm2 V?1 s?1 and contactless mobility of 24 cm2 V?1 s?1 are obtained for small‐area superlattice field‐effect transistors. Such mobility values are the highest reported for CQD devices wherein the quantum confinement is substantially present and are comparable to those reported for heavy sintering. The considerable mobility with the simultaneous preservation of the optical bandgap displays the vast potential of colloidal QD superlattices for optoelectronic applications.  相似文献   

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