- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Carrier transport and recombination dynamics of InAs/GaAs sub-monolayer quantum dot near infrared photodetector
摘要： Here, we present a relative study of tunnel-induced photocarrier escape processes in a laterally coupled InAs sub-monolayer quantum dot-based photodetector (SML QD-PD) as a function of fractional coverage from 0.4 ML to 0.8 ML. Both by simulation and experiment, we have quantitatively described the temperature dependent interband photoresponse spectrally tuned in the near infrared region (835 nm–890 nm) on the basis of mutual competition between the interband carrier recombination and interdot tunneling lifetime with varying SML coverage. The progressively increasing recombination lifetime and decreasing interdot tunneling lifetime with increasing SML coverage has attributed to a faster photoresponse and greater responsivity. At higher coverage fraction, tunnel induced fast speed photocarrier transit through lateral array of SML QDs has been found to be capable of offering a faster temporal response (100 μs) with faithful reproducibility up to higher frequencies (1.3 KHz). Here, we report a powerful strategy to simultaneously tune responsivity, speed of time response and detectivity by externally controlling the SML coverage. This time response is measured to be nine times faster than a conventional SK QD photodetector. With increased coverage, inhibition of dark current due to trapping of injected charge carriers up to higher temperatures have resulted in high sustainable photodetectivity of 8 × 1011 cm Hz1/2 w?1 at ~250 K that offers near room temperature photodetection.
关键词： photoconductive gain,quantum dot photodetector,inter-dot tunneling,submonolayer coverage,near-infrared photoresponse,recombination dynamics,temporal photoresponse
更新于2025-09-23 15:19:57
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Fabrication of rapid response self-powered photodetector using solution-processed triple cation lead-halide perovskite
摘要： Self-powered photodetectors (PDs) are suitable for application in smart systems, image sensing and optical communications. Herein, a self-powered PD based on triple cation lead-halide perovskite (TCLP) is reported. We showed the effect of bromide concentration on the optical and structural properties of the TCLP films. Additionally, an environmental stability test was conducted and it was found that TCLP with 10% Br can remain stable for up to 128 days after exposure to ambient air. Using this material, a self-powered perovskite PD was fabricated and demonstrated an impressive performance with a responsivity of 0.52 A W?1, detectivity of 8.8×1012 Jones, on/off ratio of 7.3×105, and a rapid rise and decay time of 19 μs and 21 μs, respectively. This work offers a useful insight into the effects the fabrication method of the thin film plays in building low-cost, stable, and high-performance self-powered PDs for application in structural health monitoring, imaging, optical communication, and biomedical sensing.
关键词： surface coverage,perovskite,self-powered,photodetector,triple cation
更新于2025-09-23 15:19:57
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Investigation of 100 GHz Output Power Performance in Uni-travelling Carrier Photodetector under Zero-bias Condition
摘要： This study is concerned with a design of membership functions of fuzzy sets. The membership functions are formed in such a way that they are experimentally justifiable and exhibit a sound semantics. These two requirements are articulated through the principle of justifiable granularity. The parametric version of the principle is discussed in detail. We show linkages with type-2 fuzzy sets, which are constructed on a basis of type-1 fuzzy sets. Several experimental studies are reported, which illustrate a behavior of the introduced method.
关键词： type-2 fuzzy set,interval-valued fuzzy set,principle of justifiable granularity,membership function determination,Coverage of data,specificity
更新于2025-09-23 15:19:57
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Data-Enabled Advancement of Computation in Engineering: A Robust Machine Learning Approach to Accelerating Variational Methods in Electromagnetics and Other Disciplines
摘要： One critical issue, for a wireless sensor network (WSN) to operate successfully, is to provide sufficient sensing coverage. Define the smart sensing environment as a sensing system with the capability to sense the environment and respond properly in an automated manner. In this paper, we target on smart sensing environments and deal with heterogeneous sensors (here sensor heterogeneity is defined as sensors having different sensing ranges) equipped with actuation facilities to assist in the sensor self-deployment. A coverage-aware sensor automation (CASA) protocol is proposed to realize an automated smart monitoring network. Two centralized algorithms are included in the CASA protocol suite: enhanced virtual forces algorithm with boundary forces (EVFA-B) and sensor self-organizing algorithm (SSOA). Unlike most previous works that tackle the deployment problem only partially, we intend to address the problem from both global deployment (EVFA-B) and local repairing (SSOA) perspectives. The EVFA-B protocol exerts weighted attractive and repulsive forces on each sensor based on predefined distance thresholds. Resultant forces then guide the sensors to their suitable positions with the objective of enhancing the sensing coverage (after a possibly random placement of sensors). Furthermore, in the presence of sensor energy depletions and/or unexpected failures, our SSOA algorithm is activated to perform local repair by repositioning sensors around the sensing void (uncovered area). This capability of local recovery is advantageous in terms of saving the communication and moving energies. Performance of the proposed sensor deployment strategies is evaluated in terms of surveillance coverage, monitoring density, network self-healing competence, and moving energy consumption. We also implement our CASA protocol suite in a real-life monitoring network (MoNet) to demonstrate the protocol feasibility and validate the MoNet detection capability of emergency events.
关键词： smart sensing environment,sensor automation,self-healing,coverage problem,Wireless sensor deployment
更新于2025-09-23 15:19:57
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Interleaved Readout of Charge Coupled Devices (CCDs) for Correlated Noise Reduction
摘要： Heterogeneous cellular networks (HetCNets) offer a promising solution to cope with the current cellular coverage crunch. Due to the large transmit power disparity, while following maximum power received (MPR) association scheme, a larger number of users are associated with macro-cell BS (MBS) than small-cell BSs (SBSs). Therefore, an imbalance load arrangement takes place across the HetCNets. Hence, using cell range expansion-based cell association, we can balance the load across the congested MBS. However, using MPR association scheme, users’ of?oading leads to two challenges: 1) macro-cell interference, in which the MBS interferes with the of?oaded users, and 2) coupled downlink-uplink cell association, in which a random user associates with a single tier’s base station (BS) both in uplink (UL) and downlink (DL) directions. This paper aims to address these problems while considering a two-tier scenario consisting of small-cell and macro-cell tiers. For the MBS interference mitigation, we employ a reverse frequency allocation (RFA) scheme. Besides coupled DL–UL association (Co-DUA), this paper also highlights the notion of decoupled DL–UL association (De-DUA). In De-DUA, a random user associates with two different tiers’ BSs, i.e., with one tier’s BS in the DL direction and with the other tier’s BS in the UL direction. Our results illustrate that, in comparison with the Co-DUA, De-DUA with RFA employment achieves a better coverage performance.
关键词： small-cell BSs,decoupled downlink-uplink association,Heterogeneous cellular networks,coverage performance,reverse frequency allocation
更新于2025-09-23 15:19:57
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Topological Photonics
摘要： The network densi?cation of small cells (SCs) is a promising way to cope with the explosive growth of future traf?c demands in 5G networks. However, the overall power consumption and the backhaul limitation of the network have become the key factors affecting the network performance and users’ quality-of-experience, which have great importance in 5G wireless networks. Due to the complexity of 5G networks and the variety of user behaviors, the combination of software-de?ned networks and content delivery strategy could be a more ef?cient way to manage such networks. In this paper, a cache-enabled wireless heterogeneous network with the control-plane (C-plane) and user-plane (U -plane) split is proposed, where the macro cell and SCs with different cache abilities are overlaid and cooperated together in the backhaul scenario. Using an evaluation tool composed of stochastic processes and classical power consumption model, key performance indicators, e.g., the coverage probability, throughput, and energy ef?ciency (EE), are derived as closed-form expressions or the functions of the signal-to-interference-plus-noise ratio threshold, path loss exponent, transmission power and density of macro and SCs, cache ability, ?le popularity, and backhaul capacity. Fundamental trade-offs are illustrated between EE and transmission power, EE and SC density, as well as the throughput and density of SCs. Numerical results show that the proposed cache-enabled software-de?ned networks have much higher throughput and improved EE than current LTE networks, which shows a promising solution for future cellular networks.
关键词： Cache-enabled networks,green communications,trade-off,spectral and energy efficiency,coverage probability,software defined networks
更新于2025-09-23 15:19:57
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Non-redundant array configurations for optical interferometric systems combined with a large telescope
摘要： In this paper, we propose a method to design the configuration of the interferometric array working with a large telescope. It limits the array configuration region and minimum aperture distance to make sure baseline length is in a certain interval. And it gives aperture locations by “push” and “pull” operations. The UV-plane coverage obtained from this method has the advantage that there is no overlap between UV-plane coverage from the interferometric array and the large aperture telescope, and the overall UV-plane coverage is non-redundant and symmetric. Specifically, design results with varying diameters of the large telescope are provided.
关键词： UV-plane coverage,Configuration design,Interferometric array
更新于2025-09-19 17:15:36
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Surface Coverage-Regulated Cellular Interaction of Ultrasmall Luminescent Gold Nanoparticles
摘要： Investigations for accurately controlling the interaction between functional nanoparticles (NPs) and living cells set a long-thought benefit in nanomedicine and disease diagnostics. Here, we reveal a surface coverage-dependent cellular interaction by comparing the membrane-binding and uptake of three ultrasmall luminescent gold NPs (AuNPs) with different surface coverages. Lower surface coverage leads to fast cellular interaction and strong membrane-binding but low cellular uptake, whereas high surface coverage induces slow cellular interaction and low membrane-binding but major cellular uptake. The slight number increase of cell-penetrating peptide on the surface of AuNPs shows improved cellular interaction dynamics and internalization through direct cellular membrane penetration. Furthermore, the different intrinsic emissions resulted from the surface coverage variation, especially the pH-responsive dual emissions, make the AuNPs as powerful optical probes for subcellular imaging and tracking. The findings advance the fundamental understanding of the cellular interaction mechanisms of ultrasmall AuNPs and provide a feasible strategy for the design of functional NPs with tunable cellular interaction by surface regulation.
关键词： ultrasmall gold nanoparticles,surface coverage,imaging,luminescence,cellular interaction
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE Asia Pacific Conference on Wireless and Mobile (APWiMob) - BALI, Indonesia (2019.11.5-2019.11.7)] 2019 IEEE Asia Pacific Conference on Wireless and Mobile (APWiMob) - Performance of LED Overlap in Visible Light Communication System
摘要： In this paper, we consider an indoor Visible Light Communication (VLC) system with a placement technique with and without an overlap formed, using four and five Light Emitting Diodes (LED), placements on a room roof. To support the better received signal power, this paper evaluated the performance of LED overlap using the 3-Watt transmit power. We did a computer simulation using the dimension closed communication 5x5x3 m3. In this paper, we found that the VLC system with an overlap was better than the one without an overlap. The result showed that the received power could reach the minimum Bit Error Rate (BER) threshold around -18 dBm for VLC system without an overlap and -20 dBm for VLC system with an overlap. From the simulation, it obtained that communication link coverage with an overlap was about 25 m2.
关键词： Overlap,Bit Error Rate,Coverage,Visible Light Communication
更新于2025-09-19 17:13:59
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Graphene Tunability for Transmission Type Terahertz Chiral Metamaterial
摘要： Deployment algorithms proposed to improve coverage in sensor networks often rely on the Voronoi diagram, which is obtained by using the position information of the sensors. It is usually assumed that all measurements are sufficiently accurate, while in a practical setting, even a small measurement error may lead to significant degradation in the coverage performance. This paper investigates the effect of measurement error on the performance of coverage control in mobile sensor networks. It also presents a distributed deployment strategy, namely the Robust Max-Area strategy, which uses information on error bounds in order to move the sensors to appropriate locations. To this end, two polygons are obtained for each sensor, and it is shown that the exact Voronoi polygon (associated with accurate measurements) lies between them. A local spatial probability function is then derived for each sensor, which translates the available information about the error bound into the likelihood of the points being inside the exact Voronoi polygon. Subsequently, the deployment strategy positions each sensor such that the total covered area increases. The sensors’ movements are shown to be convergent under the proposed strategy.
关键词： measurement error,mobile agents,Coverage control,Wireless sensor networks
更新于2025-09-19 17:13:59