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- 2018
- electron-transparent membranes
- micropump
- field emission electron source
- ion source
- ion mobility spectrometry
- Optoelectronic Information Science and Engineering
- Wroclaw University of Science and Technology
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Synthesis of Cu <sub/>2</sub> ZnSnSn <sub/>4</sub> nanoparticles for solar cell applications
摘要： Cu2ZnSnS4 are synthesized using hot injection method at different durations such as 3, 6, 9 and 12h. With increase in the duration to 6h, Cu3SnS4 phase appeared to be prominent together with CZTS phase. Fixing the deposition time at 3 h, the composition is varied to get a Cu poor sample Cu(Zn+Sn) ratio of 0.78 which is known to be in the optimum range for device fabricaton. These films showed tetragonal kesterite structure of CZTS with traces of wurtzite phase. Band gap varied from 1.55 to 1.3 eV and the nanoparticles have a size of ~ 8 nm. The optimized film had a resistivity of 15 (cid:2)(cid:2)cm and mobility of 8 cm2/Vs suitable for solar cells.
关键词： mobility,solar cell,kesterite,nanoparticle,Raman
更新于2025-09-16 10:30:52
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Thermal Analysis and Operational Characteristics of an AlGaN/GaN High Electron Mobility Transistor with Copper-Filled Structures: A Simulation Study
摘要： In this study, we investigated the operational characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) by applying the copper-filled trench and via structures for improved heat dissipation. Therefore, we used a basic T-gate HEMT device to construct the thermal structures. To identify the heat flow across the device structure, a thermal conductivity model and the heat transfer properties corresponding to the GaN, SiC, and Cu materials were applied. Initially, we simulated the direct current (DC) characteristics of a basic GaN on SiC HEMT to confirm the self-heating effect on AlGaN/GaN HEMT. Then, to verify the heat sink effect of the copper-filled thermal structures, we compared the DC characteristics such as the threshold voltage, transconductance, saturation current, and breakdown voltage. Finally, we estimated and compared the lattice temperature of a two-dimensional electron gas channel, the vertical lattice temperature near the drain-side gate head edge, and the transient thermal analysis for the copper-filled thermal trench and via structures. Through this study, we could optimize the operational characteristics of the device by applying an effective heat dissipation structure to the AlGaN/GaN HEMT.
关键词： thermal conductivity,high electron mobility transistor,GaN,self-heating effect,copper-filled structure
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Photovoltaic Power Generation with Module-Based Capacitive Energy Storage
摘要： The design of wireless sensor networks (WSNs) has a new paradigm that implies a separation of the underlying communication functionalities from the upper-layer protocols with the goal of leveraging the reusability of protocols. This paper provides an overview of the proposed Rings infrastructure protocol (RIP), which forms a generic flexible communication infrastructure. RIP discovers the physical topological rings that exist in an arbitrary WSN topology and produces an infrastructure of concentric rings (Rings) that reflects the physical rings of nodes in the field. The resulting infrastructure guarantees the proximity of nodes. Neighbor nodes in this logical overlay are also physical neighbors. Each ring in Rings is assigned one or more mobile robots that act as probes to access the data and monitor the ring. Access nodes are selected dynamically at each ring to act as anchors for the probes visiting their associated rings. The Rings infrastructure supports both multi-hop and data-mule communication models with a high degree of reliability. This paper focuses on creating the infrastructure: we justify its correctness and efficiency. A rough cost model that predicts the cost of communication over Rings is provided. The performance of the infrastructure is evaluated by implementing and simulating some of the upper-layer processes. Simulation-based comparisons with the multi-scale communication approach are provided, and the results show that the Rings infrastructure is both robust and efficient in supporting upper-layer processes.
关键词： Generic,overlay,rings,infrastructure,protocols,sensor networks,mobility,self-organization
更新于2025-09-16 10:30:52
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Study of p-type doping effect on P3HT: ICBA based organic photovoltaic solar cell performance
摘要： In this work, we present a simulation study for p-type doping effect on the performance of a photovoltaic organic solar cell based on P3HT: ICBA. Thus, numerical simulations are investigated on ITO/PEDOT: PSS /P3HT: PCBM/Ca/Al structure with AMPS-1D (Analysis of Microelectronic and Photonic Structures the simulation one dimension) software. Indeed, the p-type doping is considered as an original approach for the efficiency improvement of the organic solar cell. However, we noticed that this improvement is only valid for the active layer devices characterized by hole mobility μp less than 1E-3cm2V-1s-1. Furthermore, an efficiency peak of 5.856% is obtained for doping density of 1E17cm-3 corresponding to an improvement of 25.9%. Moreover, the obtained results remain in good agreement with those experimentally reported in literature.
关键词： hole mobility,efficiency,p-type doping,P3HT: ICBA,AMPS-1D,organic solar cell
更新于2025-09-16 10:30:52
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Thermal Management of GaN-on-Si High Electron Mobility Transistor by Copper Filled Micro-Trench Structure
摘要： Self-heating effect is a major limitation in achieving the full performance potential of high power GaN power devices. In this work, we reported a micro-trench structure fabricated on the silicon substrate of an AlGaN/GaN high electron mobility transistor (HEMT) via deep reactive ion etching, which was subsequently filled with high thermal conductive material, copper using the electroplating process. From the current-voltage characteristics, the saturation drain current was improved by approximately 17% with the copper filled micro-trench structure due to efficient heat dissipation. The iDS difference between the pulse and DC bias measurement was about 21% at high bias VDS due to the self-heating effect. In contrast, the difference was reduced to approximately 8% for the devices with the implementation of the proposed structure. Using Micro-Raman thermometry, we showed that temperature near the drain edge of the channel can be lowered by approximately ~22 °C in a HEMT operating at ~10.6 Wmm?1 after the implementation of the trench structure. An effective method for the improvement of thermal management to enhance the performance of GaN-on-Silicon HEMTs was demonstrated.
关键词： thermal management,high electron mobility transistor,self-heating effect,copper filled micro-trench,GaN-on-Si
更新于2025-09-16 10:30:52
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Hole-transporting materials for low donor content organic solar cells: Charge transport and device performance
摘要： Low donor content solar cells are an intriguing class of photovoltaic device about which there is still considerable discussion with respect to their mode of operation. We have synthesized a series of triphenylamine-based materials for use in low donor content devices with the electron accepting [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The triphenylamine-based materials absorb light in the near UV enabling the PC71BM to be essentially the light absorbing organic semiconducting material in the solar cell. It was found that the devices did not operate as classical Schottky junctions but rather photocurrent was generated by hole transfer from the photoexcited PC71BM to the triphenylamine-based donors. We found that replacing the methoxy surface groups with methyl groups on the donor material led to a decrease in hole mobility for the neat films, which was due to the methyl substituted materials having the propensity to aggregate. The thermodynamic drive to aggregate was advantageous for the performance of the low donor content (6 wt%) films. It was found that the 6 wt% donor devices generally gave higher performance than devices containing 50 wt% of the donor.
关键词： hole mobility,low donor content,photoexcited hole transfer,Schottky junction,synthesis,photocurrent generation
更新于2025-09-16 10:30:52
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Enhancing charge mobilities in self-assembled Na?ˉI halogen bonded organic semiconductors: A design approach based on experimental and computational perspectives
摘要： Charge transport in pyridine-ethynyliodophenyl supramolecules that involve intermolecular halogen bonding is studied by a combined experimental and computational approach. Selective fluorination of the molecules determines their crystallization pattern and is found to potentially increase the charge mobilities in the crystal. We report the synthesis of the molecules, full chemical characterization and resolved crystal structures. Computational analysis of the charge transport is provided to understand at the molecular level the structure-function relationships determining the charge mobilities. Combination of selective fluorination, halogen bonding motif and increased π system is highlighted as bearing the potential to achieve both enhanced hole and electron mobilities.
关键词： Selective fluorination and phenylation,Hole and electron mobility,Halogen bonding,Organic semiconductors,Charge transport,Density functional theory
更新于2025-09-16 10:30:52
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Photo- and electroluminescence features of films and field effect transistors based on inorganic perovskite nanocrystals embedded in a polymer matrix
摘要： The optical and electrical properties of films and field-effect transistors (FETs) based on pure MEH-PPV, neat CsPbBr3 nanocrystals (NCs), and MEH-PPV:CsPbBr3 NCs composites with different contents of CsPbBr3 NCs are investigated. The films were characterized by absorbance, atomic-force microscope and current-voltage characteristics (I-Vs) techniques. Relative PL and EL intensities and PL spectra of the pure MEH-PPV, neat CsPbBr3 NCs and MEH-PPV:CsPbBr3 NCs films were measured at 300 K at various levels of optical and electrical excitation power; these dependencies of the PL and EL intensities turned out to be sublinear and superlinear respectively. FETs based on MEH-PPV:CsPbBr3 NCs (1:1) films exhibit I-Vs at 290 – 100 K a dominant hole transport mechanism. The mobility of charge carriers was determined at 290 K for neat CsPbBr3 NCs (for electrons: 2.7 10-2 cm2/Vs) and MEH-PPV:CsPbBr3 NCs (1:1) (for holes: 9 cm2/Vs). The temperature dependence of the hole mobility μFET(T) of FETs based on MEH-PPV:CsPbBr3 NCs (1:1) films characteristic of the hopping mode. It was found that the superlinearity of the dependence of EL of MEH-PPV:CsPbBr3 NCs LE-FETs at 290 K increases with increasing concentration of CsPbBr3 NCs due to efficient energy transfer between CsPbBr3 NCs and the MEH-PPV polymer matrix, and also because of the probability of electron tunneling through the potential barrier to electrode. It is expected that the obtained MEH-PPV:CsPbBr3 NCs nanocomposite films will be useful for efficient applications in nanotechnology LEDs, FETs and LE-FETs.
关键词： Energy transfer,Field-effect transistors,Semiconducting polymers,Photo- and electroluminescence,Charge carrier mobility,Inorganic perovskite nanocrystals
更新于2025-09-16 10:30:52
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Amorphous ZnO/PbS quantum dots heterojunction for efficient responsivity broadband photodetectors
摘要： The integration of lead sulfide quantum dots (QDs) with high conductivity material that is compatible with a scalable fabrication is an important route for the applications of QDs based photodetectors. Herein, we firstly developed a broadband photodetector by combining amorphous ZnO and PbS QDs forming a heterojunction structure. The photodetector showed detectivities up to 7.9x1012 jones and 4.1x1011 jones under 640 nm and 1310 nm illumination, respectively. The role of oxygen background pressure on the electronic structure of ZnO films grown by pulsed laser deposition was systematically studied, and it was found to play an important role on the conductivity, associated to the variation of oxygen vacancy concentration. By increasing the oxygen vacancy concentration, the electron mobility of amorphous ZnO layers dramatically increased and work function decreased, which were beneficial for the photocurrent enhancement of ZnO/PbS QDs photodetectors. Our results provide a simple and highly scalable approach to develop broadband photodetectors with high performance.
关键词： oxygen vacancy,amorphous ZnO,broadband photodetector,mobility,heterojunction
更新于2025-09-16 10:30:52
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Numerical Analysis of Single Negative Broadband Metamaterial Absorber Based on Tri Thin Layer Material in Visible Spectrum for Solar Cell Energy Harvesting
摘要： A broadband nanostructure metamaterial absorber (MA) based on tri-layer metallic-optical-thin film molded shape is proposed for visible spectrum solar energy scavenging. This MA is investigated for photon mobility to achieve significant photon conversion and absorption to integrate into solar cell technology, IoT components, or energy harvesting. Design and analysis of the proposed MA were performed using the “Yee’s Finite-Difference Time-Domain (FDTD)” method based on commercially available CST microwave studio simulation software. Numerical computational tools depict an absorptivity of higher than 80%, which covered nearly the visible region 430~627 THz. This significant absorptivity can be maintained with both transverse electric and transverse magnetic polarizations. Furthermore, molded shape with two-dimensional split and nano-square window expedites the unit cell to exhibit single negative (SNG) metamaterial characteristics and photon conversion acceleration. Compared with related previously reported broadband absorbers, the proposed MA has promising application, in conventional solar cell efficiency improvement and emitter.
关键词： Absorption,Energy harvesting,Metamaterial,Photon mobility
更新于2025-09-16 10:30:52