Accurate determination of contact resistivities (P c ) below 1 × 10 -8 Ω · cm 2 is challenging. Among the frequently applied transmission line models (TLMs), circular TLM (CTLM) has a simple process ...flow, while refined TLM (RTLM) has a high Pc accuracy at the expense of a more complex fabrication. In this letter, we will present a novel model-multiring CTLM (MR-CTLM), which combines the advantages of a simple process and a high Pc extraction resolution. We fabricated ultralow -Pc Ti/n-Si contacts and demonstrated the capability of MR-CTLM to extract the P c as low as 6.2 × 10 -9 Ω · cm 2 with high precision.
In this study, a transmission line model is applied to the electrochemical impedance spectroscopy (EIS) data of the fabricated dye-sensitized solar cells (DSSCs) to evaluate the charge transfer ...mechanism through the cells. Natural dye from black plum (Syzygium cumini) fruit was used as a cell sensitizer (SC-DSSC) and compared its photovoltaic and electron transport capabilities to those of a cell using a synthetic sensitizer (N719-DSSC). TiO2/ZnO electrospun composite nanofibers were used as the semiconductor layer of the photoanode to enhance electron transfer. The EIS analysis revealed the role of electron resistances through shant, interfaces, and electrolyte solution by measuring the electron transfer kinetic parameters of each element. Based on the results, the SC-DSSC and N719-DSSC are appropriate photovoltaic cells because their ratios of effective electron diffusion length to photoanode thickness are 12.5 and 2.8, respectively. The EIS analysis showed that the electrospun composite nanofiber coated on the photoanode reduces the semiconductor layer's electrical resistance to the cell's total resistance. The extracted natural dye also boosted electron lifetime to 3.68 ms and diffusion coefficient to 54.3×10−6 m2/s while minimizing back-electron recombination at the semiconductor-electrolyte interface. Moreover, the semiconductor-electrolyte interface resistance is over 85% of the overall resistance for both DSSCs and controls electron transport through the cells, which is due to the dye-semiconductor binding intensity. Based on the photovoltaic data, the SC-DSSC cell efficiency was lower than N719-DSSC which is attributed to its higher electron transfer rate-controlling element. Thus, enhancing dye-semiconductor interactions will decrease the rate-controlling impedance and enhance cell performance.
A metamaterial-based broadband low-profile grid-slotted patch antenna is presented. By slotting the radiating patch, a periodic array of series capacitor loaded metamaterial patch cells is formed, ...and excited through the coupling aperture in a ground plane right underneath and parallel to the slot at the center of the patch. By exciting two adjacent resonant modes simultaneously, broadband impedance matching and consistent radiation are achieved. The dispersion relation of the capacitor-loaded patch cell is applied in the mode analysis. The proposed grid-slotted patch antenna with a low profile of 0.06 λ 0 (λ 0 is the center operating wavelength in free space) achieves a measured bandwidth of 28% for the |S 11 | less than -10 dB and maximum gain of 9.8 dBi.
In this article, a novel implementation of a widely used pseudo-two-dimensional (P2D) model for lithium-ion battery simulation is presented with a transmission line circuit structure. This ...implementation represents an interplay between physical and equivalent circuit models. The discharge processes of an LiNi0.33Mn0.33Co0.33O2-graphite lithium-ion battery under different currents are simulated, and it is seen the results from the circuit model agree well with the results obtained from a physical simulation carried out in COMSOL Multiphysics, including both terminal voltage and concentration distributions. Finally we demonstrated how the circuit model can contribute to the understanding of the cell electrochemistry, exemplified by an analysis of the overpotential contributions by various processes.
Transition metal oxides-based catalytic layers often present a complex 3D porous architecture affecting the evaluation of their intrinsic electrocatalytic activity. In this work the oxygen evolution ...reaction activity of core-shell Fe3O4@CoFe2O4 nanoparticles combining a conductive magnetite core and a catalytically active cobalt ferrite shell was studied at different loading and thickness of the catalytic layer. It was observed that their apparent activity is decreasing and that the Tafel slopes are becoming convex when the loading increases. The activity decay could be attributed to the significant resistance to charge transport in the thick porous catalyst layer. This resistance could be estimated by fitting the electrochemical impedance spectra using the transmission line model. The influence of the layer thickness on the experimental current-potential curves and on their Tafel slopes could be simulated using a simple model based on the Telegrapher's equations. It is concluded that in order to measure accurately the activity and Tafel slopes of an electrocatalyst, thin layers must be used, notably for catalyst layers that are not highly conductive.
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Pitting corrosion with fractal porous structure often occurs on copper tubes used in heat exchangers of air-conditioning equipment, and this corrosion is called an ant-nest corrosion. Galvanostatic ...controlled EIS (G-EIS) was used to measure 3-dimensianal (3D) impedance during the formation of ant-nest corrosion on phosphorus deoxidized copper (pd-Cu). Instantaneous impedance at an arbitrary time after galvanostatic polarization was determined from the 3D impedance. The transmission line model (TLM) for fractal porous electrode was applied to detect a branched pore formation on pd-Cu electrode. Nyquist plot of instantaneous impedance at initial stage of ant-nest corrosion shows capacitive behavior and straight line of 45° angle against real axis in high frequency region, indicating that a porous structure was formed at the initial stage. The angle of straight line was varied from 45° to 22.5 and 11.25°, indicating the formation of branched and doble-branched porous structures, respectively.
•A new passivity enforcement approach with complete formulation.•Passivity enforcement in wideband line and cable models.•First demonstration of combined perturbation of residues.•Superior ...performance in passivity enforcement compared to existing approaches.•Formulation resulting in minimum perturbation.
Passive component models are necessary to ensure numerical stability in the simulation of electromagnetic transients in power systems. However, it is challenging to represent transmission lines and cables with frequency-dependent wideband models that are accurate, efficient, and passive. This paper proposes a new method for the passivity enforcement of wideband line and cable models. The wideband models rely on pole-residue identification of characteristic admittance and propagation function in rational forms. In case the resulting models are not passive, the proposed method simultaneously applies perturbation to the residue matrices of characteristic admittance and propagation function. The set of equations related to passivity enforcement through the residues of propagation function in phase domain is complex and presented for the first time in this paper. The proposed approach minimizes the overall perturbation for maintaining passivity as opposed to the existing simplified approaches that rely on the perturbation of the residues of either characteristic admittance or diagonal elements of propagation function. The performance of the method is validated with application cases, and it is shown that it outperforms the existing methods that seek simplification in problem formulation.
In this corrigendum, we would like to point out that we have the solutions in the above paper for the cases A=B=0 (which are all correct seven cases) when using the new modified sub-ODE method. This ...correction do not alter the conclusion of the article.
As the size of a transistor decreases, the parasitic resistances of the transistor become dominant for contact resistance. In-situ phosphorus-doped epitaxial silicon with high doping concentrations ...has been used to reduce contact resistivity. In this study, we measured the contact resistivity of in-situ phosphorus-doped silicon using a circular transmission line model (CTLM). The distribution of the contact resistivity for films with high phosphorus concentrations was found to be about 400 times larger than that for films with low phosphorus concentrations. To explain the large distribution of the measured contact resistivity, the potential distribution and current flow in phosphorus-doped silicon films with various phosphorus concentrations were simulated using the CTLM and a transmission line model (TLM). In silicon films with high phosphorus doping concentrations, the greater effects of metal resistance and the vertical current reduced the accuracy of the extracted contact resistivity. A multiline transmission line model (ML–TLM) was proposed to improve the accuracy of the extracted contact resistivity at a given phosphorous concentration. The use of the ML–TLM increased the ratio of the contact resistance to the total resistance; thus, the effect of metal resistance was significantly reduced, and the accuracy of contact resistivity was improved.
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