Electrothermal Characterization Research Articles

Advancing In-Situ Sample Preparation for MEMS-Based Electrical and Electro-Thermal (S)TEM Characterization

Advancing In-Situ Sample Preparation for MEMS-Based Electrical and Electro-Thermal (S)TEM Characterization

Electrothermal Characterization of Series- and Parallel-Based Heating Textiles with Insulation Layers

Electrothermal Characterization of Series- and Parallel-Based Heating Textiles with Insulation Layers

Electrical and electrothermal characterization of silver-coated Vectran and Amberstrand yarns for wearable heating

The development and manufacturing of conductive fibers, yarns, and fabrics is increasing exponentially due to their multiple applications in wearable electronic textiles in sensors, actuators, data processing, communication, and energy storage. This paper investigated the electrical and electrothermal properties of Liberator 40 yarns and Amberstrand 166 conductive yarns for application in wearable heating textiles. The aim of the study was to find a flexible material for protective wearable resistive heating cloths in cold environments. The analytical results demonstrate that the Liberator 40 conductive yarn gave better heating performance than the Amberstrand 166 conductive yarn due to its electrothermal characteristics. In addition, Liberator 40 conductive yarn had higher long-term durability, washing resistance, and thermal stability than Amberstrand 166 conductive yarn. The average surface temperature of both the Liberator 40 and Amberstrand 166-based wearable heating fabrics was 40°C and 34.5°C at a 9 V DC power supply, respectively. Therefore, both the conductive yarns are suitable to be applied as resistive heating elements for localized wearable heating textiles.

Design approach for electric vehicle battery packs based on experimentally tested multi-domain models

This work proposes a multi-domain modelling methodology to support the design of new battery packs for automotive applications. The methodology allows electro-thermal evaluation of different spatial arrangements of the storage cells by exploiting the implementation of numerical and geometrical battery pack models. Concerning the case study on Li-NMC battery technology, the study has completed the electro-thermal characterization of the storage cells starting from the collected experimental data, considering both the thermal interactions among cells and the effects of the state of health. This work also investigates the effects of forced air-cooling systems focusing on battery pack hot spots and temperature distributions. The results show a good fit between numerical models and data obtained from single-cell experiments. The virtual linking of geometric and numerical lumped-parameter models proved to be effective in rapid battery pack prototyping for electric vehicles, helping designers and manufacturers find suitable solutions for specific automotive applications.

Electrothermal and Mechanical Characterization of Stainless Steel and Silver-Coated Cabled Yarns for Heating Application

Electrothermal and Mechanical Characterization of Stainless Steel and Silver-Coated Cabled Yarns for Heating Application

Electrothermal Characterization and Modeling of Lithium-Ion Pouch Cells in Thermal Runaway

Electrothermal Characterization and Modeling of Lithium-Ion Pouch Cells in Thermal Runaway

Electro-Thermal Characterization of Dynamical VO2 Memristors via Local Activity Modeling.

Translating the surging interest in neuromorphic electronic components, such as those based on nonlinearities near Mott transitions, into large-scale commercial deployment faces steep challenges in the current lack of means to identify and design key material parameters. These issues are exemplified by the difficulties in connecting measurable material properties to device behavior via circuit element models. Here, the principle of local activity is used to build a model of VO2 /SiN Mott threshold switches by sequentially accounting for constraints from a minimal set of quasistatic and dynamic electrical and high-spatial-resolution thermal data obtained via in situ thermoreflectance mapping. By combining independent data sets for devices with varying dimensions, the model is distilled to measurable material properties, and device scaling laws are established. The model can accurately predict electrical and thermal conductivities and capacitances and locally active dynamics (especially persistent spiking self-oscillations). The systematic procedure by which this model is developed has been a missing link in predictively connecting neuromorphic device behavior with their underlying material properties, and should enable rapid screening of material candidates before employing expensive manufacturing processes and testing procedures.

Electro-thermal properties and characterization of the flexible polyurethane-graphene nanocomposite films

The flexible film of polyurethane/graphene (PU/G) composition with the different mass fractions of reduced graphene oxide (rGO) was synthesized by the in situ polymerization method and the electrothermal properties of the films were investigated. Results show by increasing the mass fraction of rGO to 5 wt% (PU/G5), the composition goes to the percolation zone. Further, the PU with 20 wt% of rGO (PU/G20) shows good conductivity which is relatively stable at different voltages (∼135 Ω/sq). Moreover, using graphene in the PU matrix has increased its thermal stability. PU/Gs stable up to 200 °C by assisting graphene. Also, the maximum Seebeck coefficient and voltage of PU/Gs (5, 10, 20) obtain at about 45 °C and 85 °C respectively, and PU/G20 has better performance than others. In addition, the electrothermal response of PU/G20 shows good repeatability and could reach 75 °C and 45 °C by applying the 22 V and 12 V respectively. The thermal stability, good electrothermal response, and flexibility of the sample suggest it for electrical heaters and wearable applications.

Temperature-Dependent Characterization of Power Amplifiers Using an Efficient Electrothermal Analysis Technique

In this paper, we propose an efficient methodology for the electrothermal characterization of power amplifier (PA) integrated circuits. The proposed electrothermal analysis method predicts the effect of temperature variations on the key performances of PAs, such as gain and linearity, under realistic dynamic operating conditions. A comprehensive technique for identifying an equivalent compact thermal model, using data from 3-D finite element method thermal simulation and nonlinear curve fitting algorithms, is described. Two efficient methods for electrothermal analysis applying the developed compact thermal model are reported. The validity of the methods is evaluated using commercially available electrothermal computer-aided design (CAD) tools and through extensive pulsed RF signal measurements of a PA device under test. The measurement results confirm the validity of the proposed electrothermal analysis methods. The proposed methods show significantly faster simulation speed comparing to available CAD tools for electrothermal analysis. Moreover, the results reveal the importance of electrothermal characterization in the prediction of the temperature-aware PA dynamic operation.

Dual-pace transient heat conduction in vertically aligned carbon nanotube arrays induced by structure separation

Vertically aligned arrays of carbon nanotubes (CNTs) are attractive for a wide range of macroscopic applications which can exploit the remarkable properties of individual nanotubes. In this work, an abnormal behavior of CNT bundles in heat conduction is discovered under the transient electro-thermal characterization. The measured voltage change over the sample shows a dual-pace thermal response (DTR), which could not be fitted using a single thermal diffusivity heat transfer model. Instead, two thermal diffusivities are determined from the DTR phenomenon. Three rounds of cryogenic experiments are conducted to investigate the physics behind DTR phenomenon. It starts to emerge when the temperature is reduced to a certain level. After two rounds of cryogenic experiments, the DTR phenomenon becomes permanent from 295 K to 10 K. The nano-scale structure separation induced by the increased thermal strain leads to macroscale structure separation, which results in two parallel heat conduction paths responsible for the DTR phenomenon. By building a new parallel heat transfer model taking both the transient and steady-state electrical and thermal response into consideration, the area ratio of separated CNTs is determined. This result uncovers the existence of coiled morphology and nano-structure evolution of CNTs under cryogenic state and its effect on thermal and electrical transport, especially on their transient behaviors. Knowledge of the thermal transport in these CNTs arrays is important considering the fact that transient thermal response strongly affects their mechanical, optical, and electrical behaviors.

Electrothermal characterization on the interface of self-assembled Van der Waals through vias

The thermoelectric properties of InSe/multi-walled carbon nanotubes (MWCNTs) heterojunctions suitable for 3D nano-scale integration are investigated. A shielded pair through-via (SPTV) structure is manufactured in this paper, while methods for characterizing the dielectric effect and eddy current response of the heterojunction interface in the THz band are obtained. Experiments and co-simulations show that the proposed model can accurately capture the nonlinear electromagnetic coupling and thermal carrier relaxation properties in the ultra-wideband. Transient analysis indicates that vertical electrical stress bias and selenide modification can effectively improve the quantum admittance and carrier complexation efficiency at the SPTV interface, and suppress substrate thermal current accumulation. Depletion width sensitively depends on MWCNT layer number and doping concentration, while resistivity significantly effects on thermal electron collection and transient impulse response. By applying high-frequency electrical stress in the (111) direction, the heterojunction can maintain a high carrier mobility, while decrease of oxide charge helps to suppress electromagnetic coupling. This new InSe-MWCNT SPTV has great potential for 3D nano-scale optoelectronic integration.

Microstructure and electrothermal characterization of transparent reduced graphene oxide thin films manufactured by spin-coating and thermal reduction

We herein report the microstructure, optical and electrothermal properties of a series of reduced graphene oxide (RGO) thin films, which are manufactured by spin-coating (1 and 3 layers) of graphene oxide (GO) dispersion on a quartz substrate and thermal reduction at different temperatures of 800–1000 °C. The energy dispersive X-ray spectra reveal that the relative carbon content of RGO films increases from 84.3 at% to 93.5 at% with increasing the thermal reduction temperature from 800 °C and 1000 °C, whereas the oxygen content decreases from 15.7 at% to 6.5 at%. The optical transmittance of RGO1 (1 spin-coating layer) and RGO3 (3 spin-coating layers) films at 550 nm is characterized 32.7–40.8% and 6.3–12.4%, respectively, although it decreases with increasing the thermal reduction temperature. The sheet resistance of RGO1 films decreases from 5160 Ω/sq to 1220 Ω/sq with the increment of the thermal reduction temperature, whereas the sheet resistance of RGO3 films decreased from 1080 Ω/sq to 350 Ω/sq. The decreases in optical transparency and sheet resistance values of RGO thin films are due to the successful reduction of GO films with oxygen-related functional groups to electrically conductive graphene films during the thermal treatment. The RGO thin films are characterized to exhibit high performance electrothermal behavior in terms of uniform temperature distribution, controllable steady-state saturated temperatures, rapid temperature responsiveness, and electric power efficiency at input power densities.

Electrothermal Characterization and Optimization of Monolithic 3D Complementary FET (CFET)

Electrothermal Characterization and Optimization of Monolithic 3D Complementary FET (CFET)

An 800-V High-Density Traction Inverter—Electro-Thermal Characterization and Low-Inductance PCB Bussing Design

The need to increase the power density of traction inverters for the electrified transportation systems offers an opportunity to adopt silicon carbide (SiC) devices. To ensure the system reliability, it is critical to select a SiC power module that can dissipate a sufficient amount of power to avoid operating beyond the maximum allowed junction temperature. In this work, a comprehensive electro-thermal characterization procedure based on the virtual junction temperature concept is proposed to characterize the module’s maximum power dissipation as a function of coolant temperature. Using the characterization results, it is feasible to determine the module’s safe operating area for a traction application in terms of the switching frequency and the coolant temperature. The proposed characterization method is demonstrated on a custom 1200-V SiC module to validate its feasibility for an 800-V, 150-kVA traction inverter system. In addition, the design approach for a low-inductance bussing structure using heavy copper printed circuit board (PCB) is presented in this work, which leads to a snubberless, compact and low-cost system design. Measurements and experimental studies have been performed to validate the effectiveness of PCB bussing design. The overall volume of the inverter system is around 1.75 L, which leads to a volumetric power density of 86 kVA/L.

Electro-thermal and optical characterization of an uncooled suspended bolometer based on an epitaxial La0.7Sr0.3MnO3 film grown on CaTiO3/Si

The electro-thermal and optical properties of a bolometer based on an La0.7Sr0.3MnO3( LSMO) thin film with a detection area of 100 × 100 µm2 are presented. The LSMO thin film was epitaxially grown on CaTiO3/Si and patterned using a two-step etching process of ion-beam etching in argon and of reactive-ion etching in SF6, in order to etch LSMO/CaTiO3 and Si, respectively. The voltage-current (V–I) characteristics of the bolometer were measured in vacuum from 240 K to 415 K. From the V–I characteristics and a thermal model of the bolometer, the electrical responsivity was determined and compared to the optical responsivity measured with a laser diode at 635 nm. The noise equivalent power (NEP) as a function of frequency was measured by dividing the spectral noise power density by the optical responsivity. At 300 K and a bias current of 80 µA, the NEP was 2.3 × 10−11 W · Hz−1/2 in the 20–200 Hz modulation frequency range and the response time was 1.3 ms. The obtained NEP value without any absorbing layer or antennas, combined with the low value of the response time, are a very promising step towards the use of such LSMO-based bolometers for IR or THz detection.

Correction of Delay-Time-Induced Maximum Junction Temperature Offset During Electrothermal Characterization of IGBT Devices

The lifetime evaluation is strongly influenced by the measurement accuracy of the junction temperature with the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ce</sub> (T) method during power cycling test (PCT). However, the measurement delay time tmd, the time between which the load current is switched off and the test pulse is applied, induces a maximum junction-temperature offset ΔT <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">jm</sub> . The JEDEC [1] suggested square root t method is found only to be suitable for devices with surface-close heat generation and will induce errors for other devices such as IGBTs. In this article, two novel methods, the simulated ΔZ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> and the Cauer thermal model, are proposed. The principle and accuracy of these two methods are discussed in detail. Furthermore, the measured Z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> curve, or the Foster thermal model method, is proven not suitable for the correction of the maximum junction-temperature offset, as it will induce the same error as the square root t method.

Microstructures and electrothermal characterization of aromatic poly(azomethine ether)‐derived carbon films

AbstractWe report the microstructural evolution and electrothermal properties of aromatic poly(azomethine ether) (PAME)‐derived carbon films, which were fabricated by a facile spin‐coating and following carbonization at different temperatures of 300–1,000°C. For the purpose, poly[3‐(4‐nitrilophenoxy)phenylenenitrilomethine‐1,3‐phenylenemethine] (mPAME) with a high residue of ~56.4 wt% after carbonization at 1,000°C was synthesized for a polymeric precursor for carbon films. The X‐ray photoelectron spectroscopy, Raman spectroscopy, and X‐ray diffraction analyses revealed that the molecular structures of mPAME films changed into an intrinsically nitrogen‐doped graphitic structure, dominantly at the carbonization temperatures of 800–100°C. The electrical conductivity increased considerably from ~10−7 S/cm for mPAME‐derived films fabricated at 300–700°C to ~100 S/cm for the film carbonized at 800°C to ~101 S/cm for the films carbonized at 900–1,000°C. Accordingly, mPAME‐derived carbon films, which were carbonized at 900–1,000°C, exhibited excellent electrothermal performance, such as rapid temperature responsiveness, high maximum temperatures, and high electric power efficiency to relatively low applied voltages of 5–13 V.

Nonlinear Electro-Thermal Monte Carlo Device Simulation

Abstract A model of self-heating is incorporated into a cellular Monte Carlo (CMC) particle device simulator. This is done through the solution of an energy balance equation (EBE) for phonons, which self-consistently couples charge and heat transport in the simulation. First, several tests are performed to verify the applicability and accuracy of the proposed nonlinear iterative solver in the presence of convective boundary conditions, as compared to a finite element analysis (FEA) solver as well as using the Kirchhoff Transformation. Finally, a fully coupled electro-thermal characterization of a GaN/AlGaN high electron mobility transistor (HEMT) is performed, and the effects of nonideal interfaces and boundary conditions are studied.

A methodology to determine reliability issues in automotive SiC power modules combining 1D and 3D thermal simulations under driving cycle profiles

Current environmental concerns and fuel scarcity are leading to the progressive introduction of Electric Vehicles (EV) in the global fleet vehicle population. This requires significant design and research efforts from scientific community and industry to provide reliable automotive electric propulsion systems. The power modules used for automotive traction inverters can be considered as central elements of such systems. As they are subject to high electro-thermal stress during operation, Design-for-Reliability (DfR) approaches should be adopted. Thus, accurate models for electro-thermal simulations are relevant since the early design stages. However, such simulations become highly time consuming and complex when accurate thermal characterization through standardized or real driving conditions needs to be provided. In this context, this work proposes a simulation methodology that combines real-time simulation for electro-thermal characterization of the whole EV propulsion system, using a 1D equivalent thermal impedance circuit, in conjunction with 3D FEM thermal simulation. In this way, an accurate thermal characterization of the power module under driving cycles with long duration (of hundreds of seconds) can be obtained without computing heavy 3D FEM simulations. The proposed procedure allows to simplify and speed up the early design stages while maintaining high accuracy in the results.

Dynamic characterization of SiC and GaN devices with BTI stresses

The use of temperature sensitive electrical parameters for condition monitoring of power devices is widely acknowledged for conventional Si power devices. However, its use for wide bandgap devices is still the subject of research thereby making the electrothermal characterization of these devices a requirement, especially for GaN power devices. This paper investigates and compares the dynamic characteristics of SiC and GaN power devices and how these characteristics are affected by bias temperature instability from gate voltage stress. Results show that turn-ON dID/dt increases with temperature in SiC whereas it decreases with temperature in GaN. Turn-OFF dVDS/dt is marginally temperature dependent in both technologies. These electrical parameters can be subject to drift from gate oxide degradation due to charge trapping and threshold voltage drift. Initial VGS stress tests (at the rated voltages) on SiC and GaN devices show no apparent shift in VTH, however more sophisticated test methods using the body diode voltage as an indicator for VTH showed rapid VTH shift and recovery (within a few seconds) in SiC MOSFETs.