Showing papers on "Time constant published in 2022"
TL;DR: In this paper , a tribo-electrochemical impedance spectroscopy (Tribo-EIS) measurements of pure Mg were performed to identify the origin of two time constants during standard EIS measurements in NaCl solution.
14 citations
TL;DR: In this article , a 2D drift-diffusion model is presented and experimentally validated to improve the understanding of transient processes limiting the speed of OECTs, and it is shown that switching is strongly influenced by lateral ion currents that are neglected in previous models.
Abstract: A fast response of organic electrochemical transistors (OECTs) to electrical or chemical changes is essential for a widespread acceptance of this technology. However, finding design rules for fast switching OECTs is complicated by the fact that current transient device models are highly simplified and rely on a 1D approximation of the device that neglects details of the ion and hole concentration inside the transistor channel. To improve the understanding of transient processes limiting the speed of OECTs, a 2D drift‐diffusion model is presented and experimentally validated. It is shown that switching is strongly influenced by lateral ion currents that are neglected in previous models. A consistent treatment of these currents leads to a dependency of the time constants on the applied drain potential and a complex dependency of the response time constants on the detailed device geometry. In addition to an improved understanding of the transient response of OECTs, the results discussed here highlight the challenges in properly characterizing switching time constants of OECTs, and reinforce the necessity to ensure that switching is measured between two steady‐state conditions, and not between transient states.
9 citations
01 Jun 2022
TL;DR: In this article , a dynamic-decoupled parameter identification method is proposed to extract the parameters of the simplified second-order resistor-indicator (RL) of the network-based equivalent circuit model (ECM) developed by the authors.
Abstract: State-of-health (SoH) is one of the critical battery states that must be estimated and closely monitored by the on- board battery management system in electric vehicles (EVs). In this study, the battery SoH, especially the capacity fade, is calculated based on the decoupled characteristic of the charging current under the constant-voltage (CV) scenario. First, a dynamic-decoupled parameter identification method is proposed to extract the parameters of the simplified second-order resistor–inductor ( RL ) network-based equivalent circuit model (ECM), developed by the authors. Second, the dynamic characteristics of the decoupled CV charging currents at different aging states are qualitatively investigated, and the corresponding time constant is selected as a feature-of-interest (FoI) to reflect the battery capacity degradation. Third, the aging data based on two types of lithium-ion batteries are employed to evaluate the performance of the proposed method. Verification results demonstrate that the proposed parameter identification method yields a reduced computational cost with a satisfactory fitting performance, compared to the conventional methods. The proposed parameterization method and the selected FoI guarantee the root-mean-square errors of the estimated SoH less than 2%, and the comparative results further validate the superiority of the selected FoI in terms of the SoH estimation accuracy.
8 citations
TL;DR: In this paper , the stabilizing P, PD, or PDA controllers for time-delayed first-order systems extended by automatic reset (disturbance reconstruction and compensation) established by evaluating the steady state output values of the controller, yield series PI, PID or PIDA controllers.
Abstract: The article shows that the stabilizing P, PD, or PDA controllers for time-delayed first-order systems extended by automatic reset (disturbance reconstruction and compensation) established by evaluating the steady state output values of the controller, yield series PI, PID or PIDA controllers. By comparing the parameters of the given controllers tuned by the method of multiple real dominant pole, it can be shown that the obtained values of the integration time constant are many times larger than the time constants of the transients of the equivalent circuits with the stabilizing controller. The proposed interpretation of the functionality of disturbance observer included in controllers with disturbance compensation significantly helps in understanding principles of their optimal tuning, can also be used for further modifications of their operation taking into account various other limitations and establishes a unique educational framework covering most of the existing traditional, modern and postmodern controllers.
7 citations
TL;DR: In this article , two pancake coils, one dry-wound and one with solder in between turns, are prepared and tested in a variable temperature cryostat between 4.2 and 70 K.
Abstract: For future ReBCO tape based accelerator magnets it is proposed to use no- or partial inter-turn insulation to deal with quench detection and protection. In a non-insulated coil the turns are separated by a finite electrical resistance, providing a bypass for the current at hot-spots, improving thermal stability and quench detection time. However, such coils show different dynamic electromagnetic behavior compared to insulated coils under normal charging and transient quench conditions. To study such coils in detail two pancake coils, one dry-wound and one with solder in between turns, are prepared and tested in a variable temperature cryostat between 4.2 and 70 K. Properties of the coils that are studied are charge and discharge time behavior, turn-to-turn resistance, response to current stepping, and operational stability. In this paper, the first results are presented and compared to a simplified network model in order to gain further understanding into the underlying physics.
7 citations
TL;DR: In this paper , the authors propose a procedure to prepare the initial state and define a decay function that reveals the effect of the initial states in several illustrative examples, which can lead to the misinterpretation of the CPE parameter values.
Abstract: The constant phase element (CPE) is found in most battery and supercapacitor equivalent circuit models proposed to interpret data in the frequency domain. When these models are used in the time domain, the initial conditions in the fractional differential equations must be correctly imposed. The initial state problem remains controversial and has been analyzed by various authors in the last two decades. This article attempts to clarify this problem by proposing a procedure to prepare the initial state and defining a decay function that reveals the effect of the initial state in several illustrative examples. This decay function depends on the previous history, which is reflected in the time needed to prepare the initial state and on the current profile assumed for this purpose. This effect of the initial state is difficult to separate and can lead to the misinterpretation of the CPE parameter values.
4 citations
TL;DR: In this paper , a circuit model approach is adopted to better understand the differences between two popular relaxation models, the Cole Cole model (CCM) and the Pelton model (PM), along with their corresponding time constants.
Abstract: The perceived differences between two popular relaxation models [referred to here as the Cole Cole model (CCM) and the Pelton model (PM)], along with their corresponding time constants, has been a source of confusion in recent spectral induced polarization (SIP) literature. These differences complicate comparisons between experimental results recorded by different researchers. A circuit model approach is adopted to better understand the differences between these relaxation models. Either relaxation model can fit SIP datasets equally well, the sole difference corresponds to the measured relaxation time representing the voltage decay for the time domain response to a constant current signal as usually recorded in IP field surveys. The reporting of time constants from a common relaxation model will advance petrophysical investigations of the controls on SIP measurements when exploring databases compiled from previously published datasets.
4 citations
TL;DR: In this article , the authors proposed an integral methodology for modeling RTN and, for the first time, verified its capability of predicting the long-term RTN, using the concept of effective charged traps (ECTs) and transforming the need for time constant distribution to obtain the kinetics of ECT, making longterm RTNs prediction similar to predicting aging.
Abstract: Random telegraph noise (RTN) adversely impacts circuit performance and this impact increases for smaller devices and lower operation voltage. To optimize the circuit design, many efforts have been made to model RTN. RTN is highly stochastic, with significant device-to-device variations (DDVs). Early works often characterize individual traps first and then group them together to extract their statistical distributions. This bottom-up approach suffers from limitations in the number of traps it is possible to measure, especially for the capture and emission time constants, calling the reliability of extracted distributions into question. Several compact models have been proposed, but their ability to predict long-term RTN is not verified. Many early works measured RTN only for tens of seconds, although a longer time window increases RTN by capturing slower traps. The aim of this work is to propose an integral methodology for modeling RTN and, for the first time, to verify its capability of predicting the long-term RTN. Instead of characterizing properties of individual traps/devices, the RTN of multiple devices was integrated to form one dataset for extracting their statistical properties. This allows using the concept of effective charged traps (ECTs) and transforms the need for time constant distribution to obtain the kinetics of ECT, making long-term RTN prediction similar to predicting aging. The proposed methodology opens the way for assessing RTN impact within a window of ten years by efficiently evaluating the probability of a device parameter at a given level.
4 citations
TL;DR: This paper provides a tool for real-time closed-loop SPE of the neural time constant and IO curve, which can contribute novel insights in TMS studies and can be used for advanced brain research, precision medicine and personalized medicine.
Abstract: Objective. To obtain a formalism for real-time concurrent sequential estimation of neural membrane time constant and input–output (IO) curve with transcranial magnetic stimulation (TMS). Approach. First, the neural membrane response and depolarization factor, which leads to motor evoked potentials with TMS are analytically computed and discussed. Then, an integrated model is developed which combines the neural membrane time constant and IO curve. Identifiability of the proposed integrated model is discussed. A condition is derived, which assures estimation of the proposed integrated model. Finally, sequential parameter estimation (SPE) of the neural membrane time constant and IO curve is described through closed-loop optimal sampling and open-loop uniform sampling TMS. Without loss of generality, this paper focuses on a specific case of commercialized TMS pulse shapes. The proposed formalism and SPE method are directly applicable to other pulse shapes. Main results. The results confirm satisfactory estimation of the membrane time constant and IO curve parameters. By defining a stopping rule based on five times consecutive convergence of the estimation parameters with a tolerances of 0.01, the membrane time constant and IO curve parameters are estimated with 82 TMS pulses with absolute relative estimation errors (AREs) of less than 4% with the optimal sampling SPE method. At this point, the uniform sampling SPE method leads to AREs up to 16%. The uniform sampling method does not satisfy the stopping rule due to the large estimation variations. Significance. This paper provides a tool for real-time closed-loop SPE of the neural time constant and IO curve, which can contribute novel insights in TMS studies. SPE of the membrane time constant enables selective stimulation, which can be used for advanced brain research, precision medicine and personalized medicine.
3 citations
TL;DR: In this paper , a three-stage continuous-time pipelined (CTP) ADC is compared with measurements from a 3-stage CTP that targets 70dB SNDR in a 100MHz bandwidth while sampling at 800MS/s.
Abstract: The continuous-time pipelined (CTP) ADC is a promising emerging high-speed analog-to-digital conversion technique that achieves anti-alias filtering and analog-to-digital conversion in one step. Driving such a converter is easy, thanks to its resistive input impedance. RC time-constant shifts, which will occur in practice due to a change in ambient temperature, degrade the performance of such converters. The aim of this work is to understand this phenomenon, quantify the resulting SNDR degradation, and thereby derive design tradeoffs. The theory is compared with measurements from a three-stage CTP that targets 70dB SNDR in a 100MHz bandwidth while sampling at 800MS/s.
2 citations
TL;DR: In this paper , an integrated model is developed which combines the neural membrane time constant and input-output (IO) curve with transcranial magnetic stimulation (TMS), which can contribute novel insights in TMS studies.
Abstract: Objective.To obtain a formalism for real-time concurrent sequential estimation of neural membrane time constant and input-output (IO) curve with transcranial magnetic stimulation (TMS).Approach.First, the neural membrane response and depolarization factor, which leads to motor evoked potentials with TMS are analytically computed and discussed. Then, an integrated model is developed which combines the neural membrane time constant and IO curve. Identifiability of the proposed integrated model is discussed. A condition is derived, which assures estimation of the proposed integrated model. Finally, sequential parameter estimation (SPE) of the neural membrane time constant and IO curve is described through closed-loop optimal sampling and open-loop uniform sampling TMS. Without loss of generality, this paper focuses on a specific case of commercialized TMS pulse shapes. The proposed formalism and SPE method are directly applicable to other pulse shapes.Main results.The results confirm satisfactory estimation of the membrane time constant and IO curve parameters. By defining a stopping rule based on five times consecutive convergence of the estimation parameters with a tolerances of 0.01, the membrane time constant and IO curve parameters are estimated with 82 TMS pulses with absolute relative estimation errors (AREs) of less than 4% with the optimal sampling SPE method. At this point, the uniform sampling SPE method leads to AREs up to 16%. The uniform sampling method does not satisfy the stopping rule due to the large estimation variations.Significance.This paper provides a tool for real-time closed-loop SPE of the neural time constant and IO curve, which can contribute novel insights in TMS studies. SPE of the membrane time constant enables selective stimulation, which can be used for advanced brain research, precision medicine and personalized medicine.
TL;DR: In this paper , the trap analysis in the p-GaN gate high-electron-mobility transistors (HEMTs) in the OFF-state was conducted.
Abstract: In this work, the current transient method was conducted for trap analysis in the p-GaN gate high-electron-mobility transistors (HEMTs) in the OFF-state. Based on the traditional detrapping transient measurements, the pure recovery transients can be isolated by subtracting the undetected part caused by the measurement conditions. A comparison of the measured and actual recovery transients under different drain filling voltages was presented. It suggested that this method can be effective to analyze the unregular transient curves and distinguish the charge trapping type preliminarily. In addition, three traps were identified based on the time constant spectra and the hidden absolute amplitudes of traps can be corrected using the differential amplitude spectra. The information of trap levels in the buffer layer and AlGaN barrier layer was revealed, consisting of three electron traps with energy levels of 0.313, 0.265, and 0.467 eV. The identification of the traps may provide a physical foundation for better understanding of the drain-induced trapping effect during the OFF-state in p-GaN HEMTs.
04 Feb 2022
TL;DR: In this article , the authors used published data and simple physical reasoning to show that the RC problem is, in practice, a relatively minor physical issue whose importance has been unduly magnified by viewing it through the wrong lens.
Abstract: Abstract The cochlea of the mammalian inner ear includes an active, hydromechanical amplifier thought to arise via the piezoelectric action of the outer hair cells (OHCs). A classic problem of cochlear biophysics is that the long resistance-capacitance ( RC ) time constant of the hair-cell membrane produces an effective cut-off frequency much lower than that of most audible sounds. The long RC time constant implies that the OHC receptor potential—and hence its electromotile response—decreases by several orders of magnitude over the frequency range of hearing. This “ RC problem” is often invoked to question the role of cycle-by-cycle OHC-based amplification in mammalian hearing. Here, we use published data and simple physical reasoning to show that the RC problem is, in practice, a relatively minor physical issue whose importance has been unduly magnified by viewing it through the wrong lens. Indeed, our analysis indicates that the long RC time constant is actually beneficial for hearing, reducing noise and distortion while increasing the fidelity of cochlear amplification.
TL;DR: The proposed SPE method operates in real time, selects ideal stimulus parameters, detects and processes the response, and concurrently estimates the input–output (IO) curve and the first-order approximation of the activated neural target.
Abstract: Background Neurons demonstrate very distinct nonlinear activation dynamics, influenced by the neuron type, morphology, ion channel expression, and various other factors. The measurement of the activation dynamics can identify the neural target of stimulation and detect deviations, e.g., for diagnosis. This paper describes a tool for closed-loop sequential parameter estimation (SPE) of the activation dynamics through transcranial magnetic stimulation (TMS). The proposed SPE method operates in real time, selects ideal stimulus parameters, detects and processes the response, and concurrently estimates the input–output (IO) curve and the first-order approximation of the activated neural target. Objective To develop a method for concurrent SPE of the first-order activation dynamics and IO curve with closed-loop TMS. Method First, identifiability of an integrated model of the first-order neural activation dynamics and IO curve is assessed, demonstrating that at least two IO curves need to be acquired with different pulse widths. Then, a two-stage SPE method is proposed. It estimates the IO curve by using Fisher information matrix (FIM) optimization in the first stage and subsequently estimates the membrane time constant as well as the coupling gain in the second stage. The procedure continues in a sequential manner until a stopping rule is satisfied. Results The results of 73 simulation cases confirm the satisfactory estimation of the membrane time constant and coupling gain with average absolute relative errors (AREs) of 6.2% and 5.3%, respectively, with an average of 344 pulses (172 pulses for each IO curve or pulse width). The method estimates the IO curves’ lower and upper plateaus, mid-point, and slope with average AREs of 0.2%, 0.7%, 0.9%, and 14.5%, respectively. The conventional time constant estimation method based on the strength-duration (S–D) curve leads to 33.3% ARE, which is 27.0% larger than 6.2% ARE obtained through the proposed real-time FIM-based SPE method in this paper. Conclusions SPE of the activation dynamics requires acquiring at least two IO curves with different pulse widths, which needs a controllable TMS (cTMS) device with adjustable pulse duration. Significance The proposed SPE method enhances the cTMS functionality, which can contribute novel insights in research and clinical studies.
TL;DR: In this paper , the authors detect electron traps in AlInN/GaN transistors operating at room temperature by combining pulsed electrical measurement with photoionization techniques to rapidly assess their activation energies and time constants.
Abstract: The aim of this article is to detect electron traps in AlInN/GaN transistors operating at room temperature by combining pulsed electrical measurement with photoionization techniques to rapidly assess their activation energies and time constants. In addition, this technique can also reveal the presence of electron traps that cannot be observed by using pulsed measurements alone. Thus, two electron traps were identified including a deep level whose origin could be related to dislocations in the GaN buffer existing in the devices. At the same time, this study has shown that the time constants of these electron traps are inferior to 400 ns and that the electrical behavior of the components is also degraded by the presence of surface states with a time constant of 4 $\mu \text{s}$ . Moreover, these two traps are at the origin of the gate lag effects observed during the pulsed electrical characterization of the AlInN/GaN high electron mobility transistors (HEMTs). Likewise, a negative output conductance induced by a trapping effect has been put forward.
TL;DR: The analysis showed an increase in the duration of the response selection process as a function of increasing task complexity when using both paradigms with constant and adaptive values of the preparatory period duration.
Abstract: According to the sequential stage model, the selection and the execution of a motor response are two distinct independent processes. Here, we propose a new adaptive paradigm for identifying the individual duration of the response preparatory period based on the motor reaction time (RT) data. The results are compared using the paradigm with constant values of the preparatory period. Two groups of participants performed on either an easy (Group 1) or a hard (Group 2) response selection task with two types of stimuli based on the preparatory period parameters: (1) stimuli with a constant preparatory period duration of 0 or 1200 ms and (2) stimuli with adaptive preparatory period durations. Our analysis showed an increase in the duration of the response selection process as a function of increasing task complexity when using both paradigms with constant and adaptive values of the preparatory period duration. We conclude that the adaptive paradigm proposed in the current paper has several important advantages over the constant paradigm in terms of measuring the response accuracy while being equally efficiently in capturing other critical response parameters.
TL;DR: Santos-Sacchi and Navaratnam as mentioned in this paper showed that the upper bound of the frequency range is limited by the RC time constant of hair cells because the sharpness of tuning requires that the resonance frequency must be lower than the RC rolloff frequency.
12 Sep 2022
TL;DR: In this article , the authors numerically calculated the time-resolved photoluminescence spectra using the bimolecular trapping-detrapping model, and the variations of carrier lifetimes were investigated by changing the carrier recombination and trapping rate constants, as well as the concentration of available trapping states.
Abstract: We numerically calculated the time-resolved photoluminescence spectra using the bimolecular trapping-detrapping model. The variations of carrier lifetimes are investigated by changing the carrier recombination and trapping rate constants, as well as the concentration of available trapping states.
TL;DR: In this article , the authors reveal the mechanisms of degradation of capacity, charge voltage, and discharge voltage of commercially available high-nickel cathode material when it is cycled without a voltage margin by two different charge protocols: constantcurrent charging and constantcurrent, constantvoltage charging.
Abstract: The authors reveal the mechanisms of degradation of capacity, charge voltage, and discharge voltage of commercially‐available high‐nickel cathode material when it is cycled without a voltage margin by two different charge protocols: constant‐current charging and constant‐current, constant‐voltage charging. With repeated constant‐current charging, the cathode material changes to a non‐periodic cation‐mixed state, which causes a relatively low voltage degradation, whereas during constant‐current, constant‐voltage charging, the cathode material changes from a layered structure to a periodic cation‐mixed spinel‐like phase, with consequent severe voltage decay. This decay results from a reduction in the equilibrium electrode potential and an increase of overpotential which are aggravated in a periodic cation‐mixed state. The findings provide insights into the use of excess Li without charge‐voltage margin in high‐Ni cathode materials.
TL;DR: In this paper , the authors measured the response of the facet temperature of the semiconductor laser to a single pulse current with a magnitude of microseconds by using transient thermoreflection method, and then calculated the thermal time constants of the laser.
TL;DR: In this article , a semi-analytical treatment considering estimators for the variance and variance of variance for the RTS noise as a function of the time observation was obtained. And the constants of capture and emission in the case of a dominant trap and universal behaviors for the superposition from many traps were determined.
Abstract: We obtained a semi-analytical treatment considering estimators for the variance and variance of variance for the RTS noise as a function of the time observation. Our method also suggests a way to experimentally determine the constants of capture and emission in the case of a dominant trap and universal behaviors for the superposition from many traps. We present detailed closed-form expressions corroborated by MC simulations. We are sure to have an important tool to guide developers in building and analyzing low-frequency noise in semiconductor devices.
TL;DR: In this paper , an integral methodology has been proposed for dc RTN, which can not only model it at short time but also predict it at long time, making RTN prediction similar to aging prediction.
Abstract: Random telegraph noise (RTN) adversely induces time dependent device-to-device variations and requires modeling to optimize circuit design. Many early works were focused under dc test conditions, although digital circuits typically operate under ac conditions and it has been reported that ac RTN is substantially different from dc RTN. Tests on ac RTN were carried out mainly on individual traps, and a reliable statistical distribution of trap time constants for ac RTN is still missing. This prevents verifying the statistical accuracy of Monte Carlo ac RTN simulation based on compact models, especially in terms of their ability to predict ac RTN as time window increases. Recently, an integral methodology has been proposed for dc RTN, which can not only model it at short time but also predict it at long time. By introducing the concept of effective charged traps, the need for statistical distribution of trap time constants is removed, making RTN prediction similar to aging prediction. The objectives of this work are to report statistical experimental ac RTN data and to test the applicability of integral methodology to them. For the first time, it will be shown that a model extracted from a time window of 7.8 s can be used to predict the statistical distribution of long-term ( $3\times 10^{{4}}$ s) ac RTN. The dependence of ac RTN on frequency and time window is analyzed, and the contributions of carrier tunneling from gate and substrate are assessed.
20 Jul 2022
TL;DR: In this article , a simulation study of a first order plus dead time system (FOPDT) controlled with proportional integral derivative controller tuned by optimizing several objective functions and treating several different scenarios.
Abstract: This paper presents a simulation study of a first order plus dead time system (FOPDT) controlled with proportional integral derivative (PID) controller tuned by optimizing several objective functions and treating several different scenarios. Objective functions used are Integral of Absolute Magnitude of Error (IAE), Integral of Time multiplied by the Absolute Error (ITAE), Integral of the Square Error (ISE), Integral of Time multiplied by the Square Error (ITSE) and Mean of the Integral Square Error (MISE). Scenarios include unit step response and total energy effort analysis: with and without disturbance present, unit step response in case of model to true system mismatch in time constants. Time constants being dominant time constant of the process and dead time constant. optimization algorithm used is particle swarm optimization (PSO) algorithm.
17 Jul 2022
TL;DR: In this paper , a simple yet accurate least square method is proposed to identify the equivalent inertia constant of individual inertia providers, which is based on the well-known classical swing equation of synchronous machines.
Abstract: This paper proposes a simple yet accurate least square method to identify the equivalent inertia constant of individual inertia providers. The proposed method requires ambient measurements and is based on the well-known classical swing equation of synchronous machines. The proposed method shows a very good accuracy for the inertia identification of the rotational and virtual inertia in different operating conditions, including stationary ones, and can also be used to quantify the inertia support effect of the time-varying adaptive inertia.
TL;DR: In this paper , the authors show that the frequency dependence of complex conductivity and resistivity predicts two time constants that are not identical but which are related to each other, i.e., the shorter time constant τ σ predicts the current response to a voltage step and, in various models of a mineralized grain, is related to the intrinsic properties of the polarizable component, whereas the longer time constant, τ ρ, which predicts the voltage response to current step, is dependent on intrinsic material properties and also the relative volume of polarizable material as defined through chargeability.
Abstract: The underlying Cole-Cole model of the frequency dependence of complex conductivity and resistivity predicts two time constants that are not identical but which are related to each other. The shorter time constant τ σ predicts the current response to a voltage step and, in various models of a mineralized grain, is related to the intrinsic properties of the polarizable component, whereas the longer time constant τ ρ, which predicts the voltage response to a current step, is dependent on intrinsic material properties and also the relative volume of polarizable material as defined through chargeability. As a consequence, although we agree with most of the conclusions of Weller and Slater (2022), we suggest that the specification of τ σ instead of τ ρ in reference tables should probably be preferred.
TL;DR: In this paper , a portable device integrated with electronic circuits, termed PotentioCap, is described for the constantpotential coulometric readout of ion-selective membranes.
Abstract: In this work, the development of a portable device integrated with electronic circuits, termed PotentioCap, is described for the constant-potential coulometric readout of ion-selective membranes. A range of capacitors (22–220 µF) included in the device can be automatically chosen by the control software. The device was evaluated in standard pH solutions and stabilized seawater samples using a hydrogen-selective electrode placed in series with one capacitor. The transient current and integrated charge over time correlate well with that from capacitive readout using a benchtop potentiostat using an external electronic circuit. The capacitor of 47 µF is sufficient to amplify the current signal of 0.01 pH unit change with slopes of 2.68 µC/decade and 2.49 µC/decade in standard pH solutions and stabilized seawater samples, respectively. Unfortunately, however, instrumental control of the measurement protocol, as opposed to the chemical reconditioning reported earlier, results in an order of magnitude larger measurement error (precision of 0.6 mpH). To understand this the Nernst-Planck equation is used to describe the effects of constant and exponential decay currents with ion-selective membranes. Numerical simulations show that the passage of 0.2 µC of charge across the membrane causes a ∼1 % change in membrane concentration. The resulting phase boundary potential is shown to drift in the same manner as that observed experimentally with current polarized membranes. Furthermore, an improved capacitive model using an RC time constant is proposed by additionally considering the potential change with time. The model results compare favorably with the experimental data. Electric migration is shown not to be a significant contribution to the transient current. We discuss solutions to overcome the observed limitation of potential stability, which currently holds back the realization of ultra-high sensitivity measurements with ion-selective membranes.
TL;DR: In this paper , the authors obtained the transient two-stage thermal equivalent RC network of SOI MOSFETs by nano double-pulse measurement combined with network identification by deconvolution.
Abstract: The self-heating effect (SHE) of silicon-on-insulator (SOI) MOSFETs brings challenges to the measurement and modeling of transient electrothermal characteristics. For the first time, this study obtains the transient two-stage thermal equivalent RC network of SOI MOSFETs by nano double-pulse measurement combined with network identification by a deconvolution (NID) method. The two-stage model provides a comprehensive reference for the accumulation of residual heat under dynamic operation. We reveal that since the oxide layer acts as a thermal reservoir, the heat dissipation process can be divided into three phases according to thermal time constants. The results of geometry dependence of thermal parameters show that the gate length and width-to-length ratio ( ${W}/{L}$ ) increase: the thermal resistance trend of both stages decreases, the one-stage thermal time constant increases, but the two-stage thermal time constant decreases. Also, as the scaling of device dimension and mutual thermal coupling, the thermal transient response boosts significantly.
TL;DR: In this paper , the effect of oxygen annealing and epitaxial strain on the ultrafast carrier excitation and relaxation mechanism in charge-ordered (CO) manganite Pr0.5Ca 0.5MnO3 (PCMO) thin films of 60 and 150 nm thicknesses, both as-grown and annealed, was investigated by optical pump-terahertz (THz) probe measurements.
Abstract: In transition metal oxides, the potential of competing energetics of interacting fundamental entities is best displayed in perovskite manganites via the formation of a variety of exotic phases; however, there are limitations of extreme sensitivity to extrinsic and intrinsic defects and the slightest of structural modulations. Here, we report the effect of oxygen annealing and epitaxial strain on the ultrafast carrier excitation and relaxation mechanism in charge-ordered (CO) manganite Pr0.5Ca0.5MnO3 (PCMO) thin films of 60 and 150 nm thicknesses, both as-grown and oxygen annealed, as investigated by optical pump–terahertz (THz) probe measurements. Transient THz transmittance is negative for both films. Bi-exponential relaxation behavior accompanied with acoustic modulations was observed that varies along with strain and oxygen content of the films. As fitted by the sum of exponentials, the fast relaxation time constant is found to be fluence independent, while the slow relaxation time constant decreases with pump fluence for both films and is less for the annealed film suggesting that the relaxation in PCMO strongly depends on strain and oxygen content. This study on non-equilibrium carrier dynamics depicting the sensitivity of defects and subtle structural modifications is unprecedented in demonstrating the ultrafast control of CO manganites.
25 Jan 2022
TL;DR: In this paper , the authors obtained a semi-analytical treatment obtaining estimators for the sample variance and variance of sample variance for the RTS noise, which suggests a way to determine the constants of capture and emission in the case of a dominant trap and universal behaviors for the superposition from many traps.
Abstract: We obtained a semi-analytical treatment obtaining estimators for the sample variance and variance of sample variance for the RTS noise. Our method suggests a way to experimentally determine the constants of capture and emission in the case of a dominant trap and universal behaviors for the superposition from many traps. We present detailed closed-form expressions corroborated by MC simulations. We are sure to have an important tool to guide developers in building and analyzing low-frequency noise in semiconductor devices.