Temperature Sensitive Parameter Research Articles

Multimode optical thermometry using CaWO4 emission band

Optical thermometry has emerged as a promising technique for remote temperature sensing in plenty of applications, where traditional contact methods are useless. To date, many sensing strategies have been developed and realized, but most of them are based on monitoring of the single temperature dependent parameter. Here, we report simple dual-center materials (Eu3+ and Sm3+-doped CaWO4) that provide multimode optical thermometry. In addition to standard ratiometric approach based on intensity ratio between host and lanthanide emission bands, spectral position and bandwidth of CaWO4 emission band were successfully utilized as temperature sensitive parameters for the first time. It was shown that multimode sensing leads to broadening of temperature working range and enhances reliability of thermal sensing. The best thermometric characteristics were achieved for CaWO4:Sm3+ sample: Sr = 1.29 % K−1@273–673 K and δT = 0.15 K.

Review on Power Cycling Reliability of SiC Power Device

The rising demand for increased integration and higher power outputs poses a hidden risk to the long-term reliable operation of third-generation semiconductors. Thus, the power cycling test (PCT) is widely regarded as the utmost critical test for assessing the packaging reliability of power devices. In this work, low-thermal-resistance packaging design structures of SiC devices are introduced, encompassing planar packaging with dual heat dissipation, press-pack packaging, three-dimensional (3D) packaging, and hybrid packaging. PCT methods and their control strategies are summarized and discussed. Direct-current PCT is the focus of this review. The failure mechanisms of SiC devices under PCT are pointed out. The electrical and temperature-sensitive parameters adopted to monitor the aging of SiC devices are organized. The existing international standards for PCT are evaluated. Due to the lack of authoritative statements for SiC devices, it is difficult to achieve comparison research results without consistent preconditions. Furthermore, the lifetimes of the various packaging designs of the tested SiC devices under PCTs are statistically analyzed. Additionally, problems related to parameter monitoring and test equipment are also summarized. This review explores the broader landscape by delving into the current challenges and main trends in PCTs for SiC devices.

LED Junction Temperature Measurement: From Steady State to Transient State.

In this review, we meticulously analyze and consolidate various techniques used for measuring the junction temperature of light-emitting diodes (LEDs) by examining recent advancements in the field as reported in the literature. We initiate our exploration by delineating the evolution of LED technology and underscore the criticality of junction temperature detection. Subsequently, we delve into two key facets of LED junction temperature assessment: steady-state and transient measurements. Beginning with an examination of innovations in steady-state junction temperature detection, we cover a spectrum of approaches ranging from traditional one-dimensional methods to more advanced three-dimensional techniques. These include micro-thermocouple, liquid crystal thermography (LCT), temperature sensitive optical parameters (TSOPs), and infrared (IR) thermography methods. We provide a comprehensive summary of the contributions made by researchers in this domain, while also elucidating the merits and demerits of each method. Transitioning to transient detection, we offer a detailed overview of various techniques such as the improved T3ster method, an enhanced one-dimensional continuous rectangular wave method (CRWM), and thermal reflection imaging. Additionally, we introduce novel methods leveraging high-speed camera technology and reflected light intensity (h-SCRLI), as well as micro high-speed transient imaging based on reflected light (μ_HSTI). Finally, we provide a critical appraisal of the advantages and limitations inherent in several transient detection methods and offer prognostications on future developments in this burgeoning field.

Novel Temperature Calibration Method of E-Mode and D-Mode GaN Power Modules Considering Dynamic ON-Resistance

This paper presents a method for measuring temperature using the temperature sensitive parameter (TSP) of a GaN power module. Current collapse occurs in GaN high electron mobility transistors (HEMTs). This results in dynamic on-resistance because of trapped electrons. Thus, dynamic conditions should be considered to accurately measure thermal characteristics. GaN HEMTs are operated in the enhanced mode (E-mode) and depletion mode (D-mode). In this study, E-mode and D-mode GaN power modules are designed to compare their thermal characteristics. Among three common temperature-measurement methods, this work employs the TSP-based approach in consideration of the device operation, instead of those using thermo-sensitive optical or material properties. The calibration is conducted in steady-state and dynamic-state. The ambient temperature is estimated using steady-state calibration data. Power cycling is examined for considering dynamic conditions. It is confirmed that dynamic on-resistance changes according to the cycle period, on time, and number of cycles. Experiments are conducted using different values of these parameters. Finally, an equation for temperature is obtained from the experimental results. The equation precisely estimates temperature with an error of 0.7%.

Temperature rise detection in GaN high-electron-mobility transistors via gate-drain Schottky junction forward-conduction voltages

An electrical measurement method for the junction temperature and thermal resistance of GaN high-electron-mobility transistors (HEMTs) is discussed. It is based on the forward voltage drop across the gate-drain Schottky diode. During measurement of this temperature-sensitive parameter, the source is left floating while the drain is grounded. Previous studies have shown that the hot spot in GaN HEMTs is near the gate side, close to the drain. The forward voltage drop across the gate-drain diode yields higher and more consistent temperatures relative to those using the forward voltage drop across the gate-source Schottky diode. This method could potentially provide more accurate data for thermal management and reliability analyses of GaN-based HEMTs. The maximum temperature of the sample was 44.8 °C on the grate-drain side and approximately 40.5 °C on the gate-source side when the sample exhibited 3.44W thermal power consumption for 1 min. Hence, the proposed method is practical and instructive.

IGBT Junction Temperature Extraction via Voltage Integral over Voltage Rise Period

In this paper, a temperature sensitive electrical parameter (TSEP) method for insulated gate bipolar transistor (IGBT) modules junction temperature estimation based on voltage integral over-voltage rise period (VIVRP) is proposed. Firstly, combined with the principles of thermodynamic physics, the movement characteristics of internal carriers and holes are discussed, and the waveform of voltage and current during the turn-off process is studied. The feasibility of using voltage integral overvoltage period instead of voltage rise loss in junction temperature measurement is discussed and proved. At the beginning of the turn-off process, the holes in the IGBT almost remain in spatial and temporal distribution (the collector current IC remains constant), which leads the VIVRP to a cheaper TSEP method for junction temperature detection, without the high-frequency current detection equipment. Finally, the junction temperature model based on VIVRP and the extraction circuit of VIVRP are proposed. In addition, it is compared with the junction temperature detection method based on the voltage rise time and voltage rise loss. The results show that the junction temperature detection method based on VIVRP proposed in this paper is detection with high precision and low cost.

Online Monitoring Method for Junction Temperature of SiC MOSFETs based on Temperature Sensitive Electrical Parameter

Online Monitoring Method for Junction Temperature of SiC MOSFETs based on Temperature Sensitive Electrical Parameter

Machine learning-based prediction of on-state voltage for real-time health monitoring of IGBT

Real-time temperature monitoring of power semiconductors is a powerful tool for the predictive maintenance and lifetime prediction of power converters, and is typically performed by measuring temperature sensitive electrical parameters (TSEP). In this work, we demonstrate a machine learning-based method to estimate the on-state voltage of a real converter prototype featuring variable load of electric vehicle (EV) and photovoltaic (PV) systems under different ambient temperatures induced in a climate chamber. The method provides for the first-time insights on the uncertainties and feature importance for the predictions, and is aimed to be industrial compatible by applying only methods that are well established in industry. The approach is further flexible to any converter system, independently of its specifications. We have used the Support Vector Machine, K-Nearest Neighbors, and Decision Tree algorithms to predict the on-state voltage as functions of the readily measured parameters of a converter. We show that for the PV case, the K-Nearest Neighbor method yields the lowest mean absolute error of about 0.75 % for prediction, while for EV, the K-Nearest Neighbor algorithm gives the lowest mean absolute error of 5 %.

Методы и особенности измерения теплового сопротивления интегральных СВЧ-усилителей на гетеропереходных биполярных транзисторах

The method of measuring the thermal resistance (TR) of semiconductor devices (SD) according to OST 11 0944-96 and the original modulation method implemented in the hardware and software package developed by the authors are described. In both methods, the SD is heated by pulsed power, and the temperature of its active region (transition) is determined by a change in the temperature–sensitive parameter (TSP) - the voltage at the SD at a low current passed through the SD in the pauses between the pulses of the heating current. The measurement error of the vehicle by the standard method strongly depends on the choice of the duration of the heating current pulses and the delay time when measuring the voltage at the SD after switching off the heating current. In the modulation method, the duration of the heating current pulses is changed according to the harmonic law, and according to the results of measuring the voltage at the SD during the passage of the heating and measuring current, the modulus of the thermal impedance of the SD is determined as the ratio of the first harmonic of the transition temperature to the first harmonic of the heating power. According to the frequency dependence of the thermal impedance module, the components of the vehicle of the object are determined, while the requirements for maintaining the temperature of the device body are significantly reduced and, as a result, the measurement error of the vehicle is reduced. The results of comparative measurements of the TR of integrated microwave amplifiers (amplifying cascades) on InGaP/GaP HBT by the standard and modulation method at different values of the amplitude of the heating current are presented. It is shown that the results of measuring the TR of integrated microwave amplifiers by both methods are in good agreement with each other. It is established that with an increase in the amplitude of the heating current, the TR junction-case of integrated microwave amplifiers decreases, which is due to the alignment of current distribution in the structure of the GBT during heating.

Temperature instantaneous online monitoring methods of thermal runaway based on electrode process principle

With the properties of suitable operating voltage, high energy density and stable structure, sodium-ion batteries are widely used in energy storage systems as the most promising alternative to lithium-ion batteries. However, the thermal runaway of sodium ion battery has occurred easily, which poses a great threat to the whole safety system of battery. This paper discusses a method to predict and prevent thermal runaway of sodium-ion batteries by measuring electrochemical impedance of battery. Based on the electrode material with the role of temperature control detector, the working temperature inside the battery can be directly reflected and monitored in real time, and the method is not only simple, fast, accurate, efficient, but also low-cost, which can achieve real-time on-line monitoring of the temperature inside the battery. In this work, using the sodium-ion batteries for study, it has been found that the charge transfer resistance (Rct), peak current (Ip), diffusion coefficient (D0) and cell internal temperature rare the key factors in battery effeciency. Therefore, the corresponding functional relationship can be established to effectively control the normal operation of the battery by exploring instantaneous detection of temperature sensitive electrochemical parameters, and timely disposes the battery with abnormal temperature to avoid the thermal runaway.

A Fast Activation Energy Derivation (FAED) approach for Lumped Single Particle model in lithium-ion battery module-level heat generation prediction

The performance of electric vehicles (EVs) heavily relies on the durability and longevity of lithium-ion cells, which are strongly affected by operating temperatures. Various electrochemical models have been developed to investigate the impact of operating temperature on the dynamic heat generation at cell level. Among these, the Lumped Single Particle (LSP) model stands out due to its lower computational cost and higher accuracy under >1C-rates. However, key electrochemical parameters (i.e. the ohmic overpotential, exchange current, and diffusion time constant) in the LSP model are temperature-sensitive, requiring Arrhenius dependencies. Conventional activation energy measuring approaches, relying on testing under discrete fixed temperatures to obtain activation energies, are time-consuming. To address this, this paper proposes a FAED approach that fits the temperature-sensitive parameters and corresponding activation energies to experimental data with a single discharge process, reducing the testing time to a minimum of one hour. This approach was experimentally validated on a Tesla battery module (74P6S), demonstrating a good agreement between simulation and experimental results up to 1.5 C-rates, ranging from 16 ℃ to 46 ℃. Furthermore, this approach is suitable for cells with different lithium chemistries, formats, and properties, making it an effective method for thermal analysis of EV packs.

Power Cycling on Lateral GaN and β-Ga<sub>2</sub>O<sub>3</sub> Transistors

The load cycling capability of novel power semiconductors is an important aspect when estimating their lifetime in field service. The Power Cycling Test (PCT) is the standard test to evaluate the lifetime of a semiconductor device under thermo-mechanical stress. PCTs are typically performed at temperature swings (ΔT) much higher than common operating conditions, to obtain results within a reasonable time. In this work, the PCT capability of gallium nitride (GaN) and gallium oxide (Ga2O3) lateral transistors is investigated. The GaN devices were tested in two groups with different ΔT. The temperature of the devices was monitored using two different temperature sensitive electrical parameters (TSEPs) and the accuracy of both methods was evaluated by comparing the results with the temperature, monitored by using an infrared (IR) camera. For Ga2O3 devices, no data on potential TSEP exists so far, thus, the typical TSEP for silicon (Si), silicon carbide (SiC) and GaN were investigated for their applicability to Ga2O3 devices. While a PCT was conducted on the devices, the temperature was also monitored using an IR camera. The results of the comparison of TSEP and IR camera data showed, that the accuracy of the TSEP for GaN matched either the temperature of the hottest spot on the chip (VDS method), or the average chip temperature (VGS method). For the Ga2O3 devices no suitable TSEP could be obtained and only the IR camera was used for the temperature measurement. It revealed a very uneven temperature and thus, current distribution on the chip. Furthermore, both GaN and Ga2O3 devices exhibit an outstanding power cycling capability with no failure after completing several millions of cycles. Considering the difference in Young’s Modulus of Si, GaN and Ga2O3, the PCT performance of GaN on silicon devices and Ga2O3 devices should be inferior to silicon devices. Thus, both device types, the GaN transistors and the Ga2O3 transistors, showed a PCT capability much higher than expected.

A thermal resistance detection of heteromorphic devices using SiC diode’s temperature-sensitive parameters

Certain special-shaped devices, such as traveling wave tubes, can be called hollow cylindrical structures in aerospace engineering and other applications. However, the structural complexity of such devices means that their heat dissipation characteristics cannot be measured directly using conventional techniques. The present work describes a method to directly measure such devices’ thermal resistance by semiconductors’ temperature-sensitive parameters. We prepared a special probe to collect transient temperature response, and the differential structure-function curves were obtained by processing the data using the structure-function method. We demonstrate that this method can effectively characterize cylindrical devices’ thermal resistance and detect differences caused by different processes and structures.

Temperature dependent growth of InAs/InAsSb superlattices by molecular beam epitaxy for HOT mid-wavelength infrared detectors

High-quality InAs/InAs1-xSbx type-II superlattices (T2SLs) were grown on GaSb substrates by molecular beam epitaxy for high operating temperature (HOT) mid-wave infrared detectors. The optimal growth conditions for T2SLs were obtained by determining the temperature dependence of defects formation and the effect of V/III fluxes ratio on strain and composition. The material properties of proposed T2SLs grown with various temperature and Sb/In flux ratios were investigated using standard characterization methods, including high-resolution X-ray diffraction, atomic force microscopy, and photoluminescence (PL). The zero-order peak full width at half maximum (FWHM) of 18.4 arcsec, surface roughness less than 3 Å, strain balance, and distinct PL intensity is achieved in InAs/InAs0.65Sb0.35 T2SL. Temperature-dependent PL, ranging from 70 K to 240 K, shows a slight peak shift from 4.74 μm to 5.14 μm. The temperature-sensitive parameter α extracted from Varshni fitting is smaller than those of InAs/GaSb and bulk InAsSb, indicating the promising perspective of InAs/InAs1-xSbx T2SLs for HOT mid-wave infrared photodetectors.

Influence of Phosphor Saturation on 2-D Temperature Measurement in Phosphor- Converted LEDs by Microscopic Hyperspectral Imaging

We perform an experimental study on the impact of phosphor saturation on 2-D temperature measurement for InGaN/GaN-based phosphor-converted light-emitting diodes (pc-LEDs). These pc-LEDs generally consist of 455-nm InGaN/GaN-based blue LEDs and 623-nm CaAlSiN <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{3}}$</tex-math> </inline-formula> :Eu <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text{2}+}$</tex-math> </inline-formula> -based red phosphors. The advanced microscopic hyperspectral imaging system is used to monitor 2-D phosphor saturation in these used pc-LEDs. At the same time, this technique can also be used to detect 2-D surface temperature distribution in red pc-LEDs after determining the relationship between surface temperature and temperature-sensitive parameter such as the normalized emission intensity of phosphors and relevant coefficients in their linear relationships. For the ease of analysis, we propose a factor for describing phosphor saturation in pc-LEDs, which is, namely, by phosphor saturation factor (PSF). Then, the influence of phosphor saturation on temperature measurement errors based on PSF is also analyzed. Finally, we believe that this work can provide a useful guidance for experimental understanding of 2-D photo-thermal characteristics in such type of pc-LEDs, which would be extensively applied in future lighting and display fields.

A Novel IGBT Junction Temperature Detection Based on High-Frequency Model of Inductor Element

Accurate online junction temperature detection of high-power insulated gate bipolar transistor (IGBT) modules is necessary for the health management system of key equipment. The voltage rise time ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$t_{\mathrm {rv}}$ </tex-math></inline-formula> ) is a good temperature sensitive electrical parameter (TSEP), which is of great significance for its accurate online extraction. In this article, a novel IGBT junction temperature detection based on the high-frequency (HF) model of inductor element is proposed. First, the equivalent model of the inductor element in the application circuit at HF is demonstrated. Second, based on the HF model of the inductor element, it is proposed and verified that <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$t_{\mathrm {rv}}$ </tex-math></inline-formula> in the IGBT turn-off process is consistent with the HF current pulse signal on the inductor element at HF, that is, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$t_{\mathrm {rv}}$ </tex-math></inline-formula> can be indirectly obtained by extracting the HF current pulse signal. Finally, the feasibility for voltage rise time extraction and junction temperature detection through HF isolation coil is verified by experiments and simulations. The research work in this article is helpful to the online junction temperature detection and has certain theoretical significance and practical engineering value.

An On-Line Calibration Method for TSEP-Based Junction Temperature Estimation

Temperature sensitive electrical parameters (TSEP) provide an indirect and noninvasive method for on-line junction temperature estimation of power semiconductor devices. It is known that the fundamental of TSEP-based methods is to calibrate the relationship between TSEP and junction temperature in advance. However, the calibration methods in the literature need to open the module, require pretesting, or record the operating data of a converter in the entire power rating range, which are inconvenient in field applications. This article proposes an on-line and noninvasive calibration method by measuring the data at three operating states that are already existed in the regular converter operation. It is achieved by measuring the accessible heatsink/case temperature and TSEP during converter regular operation. The concept, implementation, and error analysis of the proposed method are presented in this article. Experimental verification is given to prove the effectiveness, accuracy, and convenience of the proposed method.

Сравнительный анализ методов измерения тепловых параметров интегральных СВЧ-усилителей мощности на биполярных транзисторах

A brief analysis of methods and features of measuring thermal parameters of integrated microwave power amplifiers on bipolar transistors (BT) is presented. The hardware and software complex implementing the method of measuring the thermal parameters of the amplifier according to OST 11 0944-96 and the original modulation method is described. In both methods, the temperature of the active region of BT crystals is determined by a change in a certain temperature-sensitive parameter (TSP) of BT when they are heated by pulsed power. The results of comparative measurements of the thermal resistance of the junction-housing of the L-band integrated microwave amplifier on silicon BT are presented. The optimal duration of the heating pulses in the standard method was determined based on the analysis of the previously measured transient thermal characteristics of the amplifier. To exclude the influence of transients when switching the amplifier from the heating mode to the measurement mode, the temperature of the BT crystal at the end of the heating power pulse was determined by interpolating the results of several TSP measurements under the assumption that the crystal cooling curve has a root character. It is shown that the results of measuring the thermal resistance of the junction-housing of an integral microwave amplifier by both methods are in good agreement with each other.

Monitoring Initial Solder Layer Degradation in a Multichip IGBT Module via Combined TSEPs

With the development of high power converters, the safe operation of large IGBT modules with parallel chips is of increasing importance. In a multichip module, uneven solder layer degradation translates into higher thermal resistance for some of the chips, leading to junction temperature differences between them. However, the specific meaning of a virtual junction temperature extracted from any external electric characteristic parameter of the module is not yet clear. This paper studies the physical meanings of the temperatures estimated by the threshold voltage and the Miller platform duration as well as the quasi turn- off delay time. Experimental results show that the temperature estimated from the threshold voltage is close to the highest temperature of all the chips, while that estimated from the Miller platform duration or quasi turn-off delay time is close to the average chip temperature. Making use of the difference between the two, this paper proposes a new method to monitor the initial solder layer degradation in the multichip IGBT module. Such a method using combined temperature sensitive electric parameters (TSEPs) is verified for different levels of degradation.

Gate Current in p-GaN Gate HEMTs as a Channel Temperature Sensitive Parameter: A Comparative Study between Schottky- and Ohmic-Gate GaN HEMTs

In this work, a comparison between the gate-driving requirements of p-GaN HEMTs with gate contact of Schottky and Ohmic type is presented. Furthermore, the presence of a gate current of different magnitude is experimentally verified for both types of devices. Successively, the possibility of using the gate current as a temperature-sensitive parameter and its monitoring during real circuit operation is proposed. The viability of monitoring the gate current without introducing additional complexity in the gate driver is examined through experimental measurements on commercially available p-GaN HEMTs.