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- 实验方案
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Non-doped phosphorescent organic light-emitting devices with an exciplex forming planar structure for efficiency enhancement
摘要： Organic light-emitting devices (OLEDs) consisting of a non-doped phosphorescent dye that inserted in an exciplex forming planar structure have been fabricated, and the thickness of ultrathin phosphor layer is optimized to achieve high efficiency. The results showed that OLEDs based on the exciplex interface and a 0.5 nm thick phosphorescent dye have a power efficiency, a current efficiency, and an external quantum efficiency of 37.4 lm/W, 40.5 cd/A, and 14.3%, respectively, which are almost two-folds higher than those with non-exciplex interface devices. Meanwhile, the efficiency roll-off is significantly suppressed. These improved device performances are attributed to the elimination of triplet energy leakage from exciplexes to constituting molecules, efficient energy up conversion of triplet exciplexes and complete host-guest F?rster energy transfer. These results will provide an easily-fabricated and time-saving approach for high-performance OLEDs.
关键词： non-doped,planar structure,Organic light-emitting device (OLED),exciplex,phosphorescent dye
更新于2025-09-23 15:22:29
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Modal transmission line theory of plane wave excited layered media with multiple conductive anisotropic sheets at the interfaces
摘要： A succinct and efficient transmission line formulation is presented for the analysis of plane wave excited planar multilayered uniaxial media comprising multiple conductive sheets at the interfaces. The conductive sheets may be anisotropic with a fully populated conductivity tensor, which results in the coupling the transverse-magnetic and transverse-electric waves. The transmission line formalism is thus extended to accommodate this hybrid mode of propagation. Three different algorithms for the solution of the transmission line network are developed and compared, including a numerically stable and efficient scattering matrix procedure. Numerical examples are included that validate the theoretical method.
关键词： Anisotropic conductive sheet,Terahertz,Transmission line network,Transition matrix,Graphene,Scattering matrix,Plane wave,Planar multilayer
更新于2025-09-23 15:22:29
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Different Isolation Processes for Free-Standing GaN p-n Power Diode with Ultra-High Current Injection
摘要： In this article, we report on the fabrication and high performance of power p-n diodes grown on free-standing (FS) GaN substrate. The key technique to enhance the high breakdown voltage and suppress the surface leakage current is the isolation process. The mesa-structure diode is generally formed by utilizing the inductively coupled plasma reactive ion etching (ICP-RIE); however, it always induces high surface damages and thus causes a high leakage current. In this study, we propose a planar structure by employing the oxygen ion implantation to frame the isolation region. By following the crucial process, the fabricated mesa- and planar-type diodes exhibit the turn-on voltages of 3.5 and 3.7 V, specific on-resistance (RONA) of 0.42 and 0.46 mΩ-cm2, and breakdown voltage (VB) of 2640 and 2880 V, respectively. The corresponding Baliga’s figures of merit (BFOM, i.e., VB2/RONA) are 16.6 and 18 GW/cm2, respectively. The BFOM of 18 GW/cm2 is the highest reported value for FS-GaN diode. From the temperature dependent measurements, the planar-type diode also shows the better leakage current and thermal stability than the mesa-type diode.
关键词： leakage current,Baliga’s figure of merit,breakdown voltage,planar diode,implantation,GaN substrate
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Cartagena des Indias (2018.9.10-2018.9.14)] 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Antenna Pattern Effects in a Low Sidelobe Circularly Polarized Planar Array Due to Element Errors
摘要： Random amplitude and phase errors at the elements of a phased array antenna cause elevated sidelobe levels. Formulas for predicting the sidelobe levels based on the error statistics are well known. These same random errors also cause an error in the axial ratio of a circular polarized array. This paper presents some new expressions for the change in axial ratio as a function of the random errors.
关键词： antenna arrays,axial ratio,planar arrays,circular polarization,array errors,crossed dipoles
更新于2025-09-23 15:22:29
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Exploiting Evanescent Field Polarization for Giant Chiroptical Modulation from Achiral Gold Half-Rings
摘要： For applications seeking to realize on-chip polarization discriminating nanoantennas, efficient energy conversion from surface waves to far-field radiation is desirable. However, the response of individual nanoantennas to the particular polarization states achievable in surface waves, such as evanescent fields, has not yet been thoroughly investigated. Here, we report giant modulation of visible light scattering from achiral gold half-rings when switching between evanescent surface wave excitation produced from total internal reflection of left-handed and right-handed circularly polarized light. The effect is driven by a differing relative phase between the in-plane transverse and longitudinal field oscillations of the evanescent wave depending on the incident light handedness. As longitudinal field oscillations are not found in free-space excitation, this presents a fundamentally different mechanism for chiroptical responses as traditional mechanisms for circular dichroism only account for purely transversal field oscillations. Although the half-ring scattering modulation is dependent on the wave vector orientation, an orientation invariant response is also realized in planar chiral nanoantennas composed of eight half-rings in a rotationally symmetric arrangement, with up to 50% scattering modulation observed at 725 nm. Though both structures are found to produce scattering modulation when switching the handedness of free-space light, the distinct polarization properties of evanescent fields are shown to be strictly required to observe giant scattering modulation. These results ultimately deepen our understanding of the range of possible chiroptical effects in light-matter interactions.
关键词： nanoantenna,extrinsic chirality,evanescent fields,planar chirality,polarization discrimination,longitudinal field oscillations
更新于2025-09-23 15:21:21
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SYNTHESIS OF SPARSE OR THINNED LINEAR AND PLANAR ARRAYS GENERATING RECONFIGURABLE MULTIPLE REAL PATTERNS BY ITERATIVE LINEAR PROGRAMMING
摘要： It is shown in this paper that the problem of reducing the number of elements for multiple-pattern arrays can be solved by a sequence of reweighted (cid:2)1 optimizations under multiple linear constraints. To do so, conjugate symmetric excitations are assumed so that the upper and lower bounds for each pattern can be formulated as linear inequality constraints. In addition, we introduce an auxiliary variable for each element to define the common upper bound of both the real and imaginary parts of multiple excitations for different patterns, so that only linear inequality constraints are required. The objective function minimizes the reweighted (cid:2)1-norm of these auxiliary variables for all elements. Thus, the proposed method can be efficiently implemented by the iterative linear programming. For multiple desired patterns, the proposed method can select the common elements with multiple set of optimized amplitudes and phases, consequently reducing the number of elements. The radiation characteristics for each pattern, such as the mainlobe shape, response ripple, sidelobe level and nulling region, can be accurately controlled. Several synthesis examples for linear array, rectangular/triangular-grid and randomly spaced planar arrays are presented to validate the effectiveness of the proposed method in the reduction of the number of elements.
关键词： thinned arrays,planar arrays,reconfigurable arrays,Sparse arrays,iterative linear programming,linear arrays,multiple patterns
更新于2025-09-23 15:21:21
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PATTERN SYNTHESIS FOR LARGE PLANAR ANTENNA ARRAYS USING A MODIFIED ALTERNATING PROJECTION METHOD
摘要： A pattern synthesis approach based on a modi?ed alternating projection method for large planar arrays is presented in this paper. In the alternating projection method, pattern synthesis problem is considered as ?nding the intersection between two sets: the speci?cation set and the feasible set. The former contains all the patterns that want to be obtained, while the latter contains all the patterns that can be realized. An element belongs to both sets is a solution to the problem. In this paper, a modi?ed projection operator which varies with the iteration number is introduced because the conventional alternating projection method is known to su?er from low convergence rate and/or trapping on local optimum depending on the starting point. When the planar array has a nonuniform element layout, the unequally spaced elements are interpolated into virtual uniform elements with an interpolation of the least square sense. Then the synthesis problem is converted to the problem of a uniform array. Finally, several examples are presented to validate the advantages of the proposed method. Results show that the modi?ed method is fast and obtains better results than the conventional one.
关键词： modi?ed alternating projection method,interpolation,planar antenna arrays,nonuniform element layout,pattern synthesis
更新于2025-09-23 15:21:21
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A Fluidic Interface with High Flow Uniformity for Reusable Large Area Resonant Biosensors
摘要： Resonant biosensors are known for their high accuracy and high level of miniaturization. However, their fabrication costs prevent them from being used as disposable sensors and their effective commercial success will depend on their ability to be reused repeatedly. Accordingly, all the parts of the sensor in contact with the ?uid need to tolerate the regenerative process which uses different chemicals (H3PO4, H2SO4 based baths) without degrading the characteristics of the sensor. In this paper, we propose a ?uidic interface that can meet these requirements, and control the liquid ?ow uniformity at the surface of the vibrating area. We study different inlet and outlet channel con?gurations, estimating their performance using numerical simulations based on ?nite element method (FEM). The interfaces were fabricated using wet chemical etching on Si, which has all the desirable characteristics for a reusable biosensor circuit. Using a glass cover, we could observe the circulation of liquid near the active surface, and by using micro-particle image velocimetry (μPIV) on large surface area we could verify experimentally the effectiveness of the different designs and compare with simulation results.
关键词： micro-machining,microengineering,biosensor,?uidic interface,planar ?ow
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - The stable and long lifetime planar field emission cathode made of a CNT ink
摘要： We present the planar cathode that is dedicated for the miniaturized transmission electron microscope, which all components are fabricated based on MEMS Si-glass technology processes. The cathode is made of a commercial CNT ink without addition of fillers, and results in the stable and long lifetime field emission of electrons.
关键词： planar cathode,MEMS,field emission,CNT ink,TEM
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Electron emission from nanocrystalline silicon planar cathode in gaseous environments
摘要： The insensitivity of planar cathodes based on oxidized nanocrystalline silicon to ambient gas pressure is investigated. We demonstrate that the device operates normally even in the ambient gas pressure of 1×10 -2 Pa. The result of the energy analysis of emitted electrons suggests that emitted increase under hydrogen loss electrons with at atmosphere. less energy
关键词： environmental insensitivity,planar cathode,nanocrystalline silicon
更新于2025-09-23 15:21:21