Changes In Series Resistance Research Articles

An Experimentally Parameterized Equivalent Circuit Model of a Solid-State Lithium-Sulfur Battery

This paper presents and parameterizes an equivalent circuit model of an all-solid-state lithium-sulfur battery cell, filling a gap in the literature associated with low computational intensity models suitable for embedded battery management applications. The paper addresses this gap by parameterizing a three-state equivalent circuit model using experimental pulse power characterization data from a laboratory-fabricated lithium-sulfur cell. The cell is mechanically loaded during electrical cycling to achieve maximum ionic conductivity and consistent capacity. A nested combination of linear and nonlinear least squares regression is used to estimate the model parameters. The model captures slow cycling and fast pulse charge/discharge dynamics within 34 mV RMS error. The series resistance changes significantly at high/low states of charge and low C-rates. A sensitivity analysis determines that accurately modeling the dependence of resistance on C-rate and state of charge is important for model fidelity.

Observations of contact resistance in TOPCon and PERC solar cells

In this article we investigate the observation of increased contact resistance in both PERC and TOPCon solar cells linked to hydrogen dynamics at the interface. We study the changes in series resistance (RS) as a result of applied forward and reverse bias in the temperature range from 350 °C–400 °C. In PERC cells, we use a modified geometry to isolate the root cause of the increased RS by isolating the current path through the different parts of the cell. We show that contact resistance in PERC cells occurs between the Ag contact and the n + silicon region at the front surface. We also report the first observation of increased contact resistance in industrial n-type TOPCon solar cells, likely linked to H dynamics. For both PERC and TOPCon cells, we show that the temperature of the measurement has a profound impact on the amount of contact resistance. However, the response of the two cell architectures under varied biasing conditions is not identical. TLM measurements reveal that in TOPCon cells the increased RS is caused by the Ag contact to the n + polysilicon region, which, unlike in PERC cells, corresponds to the rear surface, away from the p-n junction. Recent results have shown that severe surface-related degradation in TOPCon solar cells can be mitigated by annealing treatments at temperatures similar to those explored herein. Therefore, identifying contact resistance in TOPCon cells may have a profound impact on further studies exploring degradation mitigation pathways in TOPCon cells.

Graphene-silicon Schottky devices for operation in aqueous environments: Device performance and sensing application

Graphene/silicon Schottky diodes have recently been of heightened interest due to their high sensitivity towards surface chemical modifications. Here we demonstrate the operation of a graphene/n-type silicon Schottky junction in aqueous media, quantifying the impacts of the ionic strength, oxidation-reduction potential, and pH of an aqueous solution on diode characteristics. The roles of the electrical double layer and the surface functional groups of graphene in determining the graphene/silicon junction response to changes in the aqueous environment were investigated. The application of this diode sensor design was demonstrated in an aqueous environment by the introduction of functional groups to the graphene surface via non-covalent functionalization (here with 1-aminopyrene). Free chlorine - a common disinfectant for drinking water - is used to illustrate the sensing capabilities of this new platform, demonstrating up to 80% change in series resistance (4% change in Schottky barrier height) of the functionalized device upon exposure to 1 ppm free chlorine, while the unfunctionalized device only shows a 17% response. The results achieved in this study will open up new opportunities for highly sensitive detection of (bio)analytes using graphene/silicon diode devices in aqueous environments, beyond their conventional gas sensing applications.

Assessment of Series Resistance Components of a Solar PV Module Depending on Its Temperature Under Real Operating Conditions

Among the physical parameters of the standard single diode model of a solar cell, series resistance is one of those that strongly affects its performance. Contradictory changes in series resistance depending on temperature were reported in the literature. Accurate measurements of I-V characteristics were taken under different real operating conditions at constant temperature and solar irradiance, using a high-performance I-V curve tracer. The experimental results were used to determine series resistance of a photovoltaic module using two extraction methods. Empirical laws of series resistance components depending on module operating temperature were cheeked. It emerges that of the seven series resistance components, only four essentially determine its value.

What Limits the Efficiency of High-Power InGaN/GaN Lasers?

Blue light emitting InGaN/GaN lasers currently exhibit less than 40% wall-plug efficiency, while infrared InGaAs/GaAs laser diodes exceed 70%. This paper explores the reasons behind the efficiency limitation by the numerical analysis of measured InGaN/GaN laser characteristics. The study reveals a strong increase of the threshold current due to self-heating. The influence of Auger recombination, electron leakage, free-carrier absorption, and series resistance changes with rising injection current.

Low Reverse Saturation Current Density of Amorphous Silicon Solar Cell Due to Reduced Thickness of Active Layer

One of the most important characteristic curves of a solar cell is its current density-voltage (J-V) curve under AM1.5G insolation. Solar cell can be considered as a semiconductor diode, so a diode equivalent model was used to estimate its parameters from the J-V curve by numerical simulation. Active layer plays an important role in operation of a solar cell. We investigated the effect thicknesses and defect densities (N_d) of the active layer on the J-V curve. When the active layer thickness was varied (for N_d = 8×10¹⁷ cm^-3) from 800 nm to 100 nm, the reverse saturation current density (J_o) changed from 3.56×10^-5 A/cm² to 9.62×10^-11 A/cm² and its ideality factor (n) changed from 5.28 to 2.02. For a reduced defect density (N_d = 4×10¹⁵ cm^-3), the n remained within 1.45≤n≤1.92 for the same thickness range. A small increase in shunt resistance and almost no change in series resistance were observed in these cells. The low reverse saturation current density (J_o = 9.62×10^-11 A/cm²) and diode ideality factor (n = 2.02 or 1.45) were observed for amorphous silicon based solar cell with 100 nm thick active layer.

Real-Time Series Resistance Monitoring in PV Systems Without the Need for I–V Curves

We apply the physical principles of a familiar method, suns-V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> , to a new application: the real-time detection of series resistance changes in modules and systems operating outside. The real-time series resistance (RTSR) method that we describe avoids the need for collecting I-V curves or constructing full series resistance-free I-V curves. RTSR is most readily deployable at the module level on microinverters or module-integrated electronics, but it can also be extended to full strings. Automated detection of series resistance increases can provide early warnings of some of the most common reliability issues, which also pose fire risks, including broken ribbons, broken solder bonds, and contact problems in the junction or combiner box. We describe the method in detail and describe a sample application to data collected from modules operating in the field.

Bending phenomenon of temperature calibration curve in junction temperature measurement by the high transient current

To measure the junction temperature of diodes under operating conditions, the temperature calibration curve is studied under large current conditions. To avoid the self heating by the large current conditions, pulsed currents are used in the paper. The temperature calibration curve of TO-247-2L fast recovery diode is investigated in this paper. The 0-1.5 A pulse current, of which the pulse width is 250 μs and the duty cycle is 5%, is chosen to study the temperature calibration curves under 50, 70, 90, 110, 130 ℃ respectively.#br#The results show that under the large current condition, the temperature calibration curve bends. The main reason for the bending phenomenon is that the series resistance changes with temperature increasing, which is affected by the mobilities of electrons and holes in semiconductor material. With the temperature rising, the mobility decreases, which results in the increasing of series resistance. Due to the series resistance increasing The voltage on p-n junction will be reduced. For this reason, a higher voltage is needed to obtain the same current, and the temperature calibration curve will bend.#br#There are two reasons which will lead to the temperature rising. The first reason is self-heating of devices by the power dissipation, and the second reason is that the temperature of device is heated by ambient temperature. Under the same temperature, self-heating behaviors of device by different currents will result in different series resistances. But in the paper, the results show that the series resistances under different currents are the same, which illustrates that self-heating is not the key reason for the change of series resistance. So, the temperature changing of the diode is caused by the ambient temperature rising, which verifies that the bending phenomenon of the temperature calibration curve of TO-247-2L fast recovery diode is caused by the ambient temperature rising.#br#Then, through experimental measurements and theoretical calculations, the accurate nonlinear temperature calibration curve is acquired, which can reduce the measurement errors of high current transient junction temperature.

Age‐dependent remodelling of inhibitory synapses onto hippocampal CA1 oriens‐lacunosum moleculare interneurons

Stratum oriens-lacunosum moleculare interneurons (O-LM INs) represent the major element of the hippocampal feedback inhibitory circuit, which provides inhibition to the distal dendritic sites of CA1 pyramidal neurons. Although the intrinsic conductance profile and the properties of glutamatergic transmission to O-LM INs have become a subject of intense investigation, far less is known about the properties of the inhibitory synapses formed onto these cells. Here, we used whole-cell patch-clamp recordings in acute mouse hippocampal slices to study the properties and plasticity of GABAergic inhibitory synapses onto O-LM INs. Surprisingly, we found that the kinetics of inhibitory postsynaptic currents (IPSCs) were slower in mature synapses (P26-40) due to the synaptic incorporation of the α5 subunit of the GABA(A) receptor (a5-GABA(A)R). Moreover, this age-dependent synaptic expression of a5-GABA(A)Rs was directly associated with the emergence of long-term potentiation at IN inhibitory synapses. Finally, the slower time course of IPSCs observed in O-LM INs of mature animals had a profound effect on IN excitability by significantly delaying its spike firing. Our data suggest that GABAergic synapses onto O-LM INs undergo significant modifications during postnatal maturation. The developmental switch in IPSC properties and plasticity is controlled by the synaptic incorporation of the a5-GABA(A)R subunit and may represent a potential mechanism for the age-dependent modifications in the inhibitory control of the hippocampal feedback inhibitory circuit.

Thermal stability of SiC Schottky diode anode and cathode metalisations after 1000 h at 350 °C

The thermal stability of two commercially available silicon carbide Schottky diode types has been evaluated following a 1000 h non-biased storage test under vacuum at 350 °C. The Ti-based Schottky (Anode) contact shows excellent stability over the duration of the test with less than 5% change in either extracted Schottky barrier height or ideality values. The Al die attach metalisation on the anode also shows no evidence of degradation after the test. However, a considerable change in series resistance was observed for both diode types, with up to a factor of 100 measured for one of the diodes. The primary early failure mode is related to degradation of the NiAg Ohmic (cathode) die attach metalisation. Demixing of the NiAg alloy, leading to Ag agglomeration is proposed to be the underlying degradation mechanism involved resulting in delamination of the die attach metalisation and the corresponding series resistance increase.

Study on long term reliability of photo-voltaic modules and analysis of power degradation using accelerated aging tests and electroluminescence technique

Abstract To improve PV module's lifetime and reliability, it is essential to understand the mechanisms and causes that degrade module performance over time under different climatic conditions. In this study, our main aim is to correlate the degradation of module power with physical changes that are generated in the cells over time. The poly-crystalline silicon 200W modules are subjected to long term accelerated tests (testing to be continued until failure occurs) and cell level defects are characterized using electroluminescence (EL) technique. The characterization is done periodically to analyze the trend of physical changes occurring in the module under aggravated stresses and degrading module's performance. Also, change in series resistance under thermal stress is analyzed as it has a direct impact on module's output power. Iterative simulation based software and EL images have been used to estimate series resistance of the cells.

Selective Inhibition of Cav3.3 T-type Calcium Channels by Gαq/11-coupled Muscarinic Acetylcholine Receptors

T-type calcium channels play critical roles in controlling neuronal excitability, including the generation of complex spiking patterns and the modulation of synaptic plasticity, although the mechanisms and extent to which T-type Ca(2+) channels are modulated by G-protein-coupled receptors (GPCRs) remain largely unexplored. To examine specific interactions between T-type Ca(2+) channel subtypes and muscarinic acetylcholine receptors (mAChRS), the Cav3.1 (alpha(1G)), Cav3.2 (alpha(1H)), and Cav3.3 (alpha) T-type Ca(2+)(1I)channels were co-expressed with the M1 Galpha(q/11)-coupled mAChR. Perforated patch recordings demonstrate that activation of M1 receptors has a strong inhibitory effect on Cav3.3 T-type Ca(2+) currents but either no effect or a moderate stimulating effect on Cav3.1 and Cav3.2 peak current amplitudes. This differential modulation was observed for both rat and human T-type Ca(2+) channel variants. The inhibition of Cav3.3 channels by M1 receptors is reversible, use-independent, and associated with a concomitant increase in inactivation kinetics. Loss-of-function experiments with genetically encoded antagonists of Galpha and Gbetagamma proteins and gain-of-function experiments with genetically encoded Galpha subtypes indicate that M1 receptor-mediated inhibition of Cav3.3 occurs through Galpha(q/11). This is supported by experiments showing that activation of the M3 and M5 Galpha(q/11)-coupled mAChRs also causes inhibition of Cav3.3 currents, although Galpha(i)-coupled mAChRs (M2 and M4) have no effect. Examining Cav3.1-Cav3.3 chimeric channels demonstrates that two distinct regions of the Cav3.3 channel are necessary and sufficient for complete M1 receptor-mediated channel inhibition and represent novel sites not previously implicated in T-type channel modulation.

Proton Irradiation of Silicon Schottky Barrier Power Diodes

Commercial silicon Schottky barrier power diodes have been subjected to 203 MeV proton irradiation and the effects of the resultant displacement damage on the I-V characteristics have been observed. The diodes show excellent resistance to radiation damage. Changes in forward and reverse bias I-V characteristics are reported for irradiated commercial Schottky barrier diodes at fluences up to 4times1014 p/cm2. Small changes are seen in the reverse bias I-V characteristics with increasing irradiation fluence. In forward bias, the series resistance is observed to increase as the fluence increases. The changes in series resistance are interpreted as being due to changes in the effective dopant density due to carrier removal by the defects produced

Displacement damage effects on the forward bias characteristics of SiC Schottky barrier power diodes

Commercial SiC Schottky barrier power diodes have been subjected to 203 MeV proton irradiation and the effects of the resultant displacement damage on the I-V characteristics have been observed. The diodes show excellent resistance to radiation damage. Changes in forward and reverse bias I-V characteristics are reported for irradiated 4H SiC commercial Schottky barrier diodes at fluences up to 2.5/spl times/10/sup 14/ p/cm/sup 2/. Small changes are seen in the reverse bias I-V characteristics with the reverse leakage actually decreasing with increasing irradiation fluence. In forward bias, the series resistance is observed to increase as the fluence increases. The changes in series resistance are interpreted as being due to changes in the effective dopant density due to carrier removal by the defects produced.

High Temperature Hydrocarbon Sensing with Pt-Thin Ga&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-SiC Diodes

Silicon carbide based metal-oxide-semiconductor (MOS) devices are attractive for gas sensing in harsh, high temperature environments. We present a hydrocarbon gas sensor based on a Pt–thin Ga2O3–SiC device. This sensor has been employed as a Schottky diode, and is capable of operating at temperatures around 600°C. Exposure to propene (C3H6) gas results in shift towards lower voltages in the current-voltage (I-V) characteristic curve, as well as a change in series resistance of the diode. The Ga2O3 thin films were prepared by the sol-gel process and deposited onto the SiC by spin coating. The Pt layer was deposited on the top of the Ga2O3, forming the Schottky contact. It also serves to dehydrogenate the hydrocarbons. The sensors responses were stable and repeatable towards propene at operating temperatures between 300 and 600°C. In this paper the effect of biasing is investigated by analyzing the output voltage of the diodes when biased at different constant currents.

Back-gate and series resistance effects in LDMOSFETs on SOI

Detailed experimental results are used to develop a new model for the linear region of operation of lateral DMOSFETs (LDMOSFETs) on silicon-on-insulator (SOI) that includes the influence of the buried oxide and back-gate. Back-gate biasing results in double-channel conduction and bias-dependent series resistance. Pertinent techniques for parameter extraction are presented and contrasted to those currently used in low-voltage SOI MOSFETs. The typical feature of LDMOSFETs is the significant change in series resistance as the back-gate is driven from accumulation to inversion. The model allows a clear identification of the architectural and technological parameters of the device.

Passive glial cells, fact or artifact?

Astrocytes that are recorded in acute tissue slices of rat hippocampus using whole-cell patch-clamp, commonly exhibit voltage-activated Na+ and K+ currents. Some reports have described astrocytes that appear to lack voltage-activated currents and proposed that these cells constitute a subpopulation of electrophysiologically passive astrocytes. We show here that these cells can spontaneously change during a recording unmasking expression of previously suppressed voltage-activated currents, suggesting that such cells do not represent a subpopulation of passive astrocytes. Superfusion of a low Ca2+/EGTA solution was able to reversibly suppress voltage-activated K+ currents in cultured astrocytes. Currents were restored upon addition of normal bath Ca2+. These effects of Ca2+ on both outward and inward K+ currents were dose- and time-dependent, with increasing concentrations of Ca2+ (from 0 to 800 micrometers) leading to a gradual unmasking of voltage-dependent outward and inward K+ currents. The transition from an apparently passive cell to one exhibiting prominent voltage-activated currents was not associated with any changes in membrane capacitance or access resistance. By contrast, in cells in which low access resistance or poor seal accounted for the absence of voltage-activated currents, improvement of cell access was always accompanied by changes in series resistance and membrane capacitance. We propose that spillage of pipette solution containing low Ca2+/EGTA during cell approach in slice recordings and/or poor cell access, lead to a transient masking of voltage-activated currents even in astrocytes that express prominent voltage-activated currents. These cells, however, do not constitute a subpopulation of electrophysiologically passive astrocytes.

The relationship between the resistance of a membrane patch and predicted changes in total patch circuit resistance secondary to spontaneous or induced alterations in patch geometry

The objective of this study was to determine the relationship between the magnitude of the membrane resistance in the free area of a cell-attached patch-clamp recording and the change in total patch circuit resistance that would be produced by the introduction of a series resistance, such as would be observed upon acquiring a patch-clamped membrane vesicle. The results describe a method for determining the magnitude of the membrane resistance in the free area of a membrane patch, and demonstrate that: (a) at a given value of shunt resistance, areas of membrane with higher resistivity produce smaller proportional increases in total patch circuit resistance upon acquiring a membrane vesicle; and (b) a presumption of spherical vesicle formation provides a lower limit estimate of the membrane resistance. The described procedures and relationships are useful in developing new techniques for examining channel activity in membrane patches where individual events are below the present limits of detection, for examining changes in membrane resistivity and/or shunt resistance in patches undergoing cytoskeletal re-organization, and for assessing the potential influence of series resistance changes on single channel parameters in longer term cell-attached patch-clamp recordings.

Influence of Intracellular Renin on Heart Cell Communication

The influence of intracellular renin and angiotensinogen on the control of cell-to-cell communication in heart muscle was investigated in cell pairs isolated from adult rat ventricle. Junctional conductance was measured with two separated voltage-clamp circuits. Intracellular dialysis of renin (0.2 pmol/L) caused a decrease in junctional conductance of 29 +/- 3.8% (+/- SEM, P < .05) in 7 minutes. The effect of renin on junctional conductance seems to be mainly due to the synthesis of Ang II because enalaprilat (10(-9) mol/L) dialyzed into the cell caused an appreciable reduction in the effect of renin. The intracellular administration of renin (0.2 pmol/L) plus angiotensinogen (0.4 pmol/L) produced a faster and stronger fall in junctional conductance (84.3 +/- 1.35%, P < .05), and the effect was greatly reduced by enalaprilat. The effects of both renin and angiotensinogen on junctional conductance were not related to a fall in surface cell membrane resistance or a change in series resistance. The effect of renin on junctional conductance was blocked by intracellular administration of a renin inhibitor (S 2864). Moreover, renin dialyzed into just one cell of the pair induced rectification of the junctional membrane, which was prevented by enalaprilat. The results support the view that an intracrine renin-angiotensin system in the heart regulates intercellular communication.

Intracellular signal transduction systems do not regulate Na channel in frog ventricular cells

The regulation of sodium channel activity through intracellular signal transduction systems was studied on isolated frog ventricular cells using a whole cell patch-clamp technique. Special care was exercised in evaluating the stability of the voltage-clamp condition by observing shifts in the steady-state inactivation curve (h infinity curve) and changes in series resistance. We applied the following reagents: isoproterenol (Iso; 0.1-10 microM) and forskolin (Fsk; 0.1-10 microM) to activate protein kinase A. 1-Oleoyl-2-acetyl-sn-glycerol (40 microM) and 12-O-tetradecanoylphorbol-13-acetate (80-800 nM) were used to activate protein kinase C, and phenylephrine (0.1-10 microM), dopamine (0.1-10 microM), and histamine (10 microM) were used to stimulate alpha-adrenergic, dopaminergic, and histaminergic receptors, respectively. The current-voltage relationship and the h infinity curve for the sodium channel remained unchanged regardless of the application of these reagents. Iso and Fsk did not affect the sodium current but substantially increased the calcium current, suggesting that the intracellular signal transduction systems remained intact. Therefore, it is concluded that sodium channel in frog ventricular cells is not regulated by intracellular signal transduction systems.