Electro-thermal Device Models Research Articles

A Datasheet-Driven Electrothermal Averaged Model of a Diode–MOSFET Switch for Fast Simulations of DC–DC Converters

The design of modern power electronics converters requires accurate electrothermal device models enabling a straightforward parameter estimation and fast, yet accurate, circuit simulations. In this paper, a novel electrothermal averaged model of a diode–MOSFET switch for fast analysis of DC–DC converters is proposed. The model has the form of a SPICE-compatible subcircuit and allows computing in a very short simulation time the DC characteristics of the converter, the waveforms of the terminal voltages and currents of the semiconductor devices, as well as their junction temperatures, both in CCM and DCM.. All the input data required by the parameter estimation procedure can be taken from the datasheets of components. The correctness of the proposed approach is experimentally verified for a buck converter chosen as a case-study. A generally good agreement between measurements and simulations is obtained; as an example, the absolute error in assessing the MOSFET junction temperature does not exceed 12 °C within the whole range of switching frequency of the converter, while the commonly used PLECS model considerably underestimates it.

Thermal performance of diamond field-effect transistors

In this report, the thermal performance of a hydrogen (H)-terminated diamond field-effect transistor (FET) is investigated using Raman spectroscopy and electrothermal device modeling. First, the thermal conductivity (κdiamond) of the active diamond channel was determined by measuring the temperature rise of transmission line measurement structures under various heat flux conditions using nanoparticle-assisted Raman thermometry. Using this approach, κdiamond was estimated to be 1860 W/m K with a 95% confidence interval ranging from 1610 to 2120 W/m K. In conjunction with measured electrical output characteristics, this κ was used as an input parameter for an electrothermal device model of an H-terminated diamond FET. The simulated thermal response showed good agreement with surface temperature measurements acquired using nanoparticle-assisted Raman thermometry. These diamond-based structures were highly efficient at dissipating heat from the active device channel with measured device thermal resistances as low as ∼1 mm K/W. Using the calibrated electrothermal device model, the diamond FET was able to operate at a very high power density of 40 W/mm with a simulated temperature rise of ∼33 K. Finally, the thermal resistance of these lateral diamond FETs was compared to lateral transistor structures based on other ultrawide bandgap materials (Al0.70Ga0.30N, β-Ga2O3) and wide bandgap GaN for benchmarking. These results indicate that the thermal resistance of diamond-based lateral transistors can be up to ∼10× lower than GaN-based devices and ∼50× lower than other UWBG devices.

Surge current capability of ultra-wide-bandgap Ga2O3 Schottky diodes

β-Ga2O3 is an emerging ultra-wide-bandgap semiconductor material offering superior power material limits over Si, SiC, and GaN as well as the availability of large-diameter wafers growing from its own melt. However, β-Ga2O3 devices performance may be limited by the relatively poor thermal conductivity of the material.In this paper, we investigate the behavior of β-Ga2O3 Schottky diodes in the condition of forward current surge to explore their electro-thermal ruggedness and the related thermal management. An analytical electro-thermal device model is calibrated with experimental devices and TCAD simulations. Then this device model is incorporated into a SPICE electro-thermal network model, which is used to simulate the device temperature rise during the surge transient, considering various device and packaging configurations (i.e. various chip thicknesses and chip orientations).It is found that provided heat is removed from the junction side, a β-Ga2O3 Schottky diode offers a robustness to surge current exceeding that of a SiC Schottky diode. The low thermal conductivity of β-Ga2O3 is found to be overcome by the enhanced heat extraction from junction-side cooling, as well as by the intrinsically small temperature dependence of the on-resistance (and conduction loss) of β-Ga2O3 devices.

Electro-thermal co-design of β -(AlxGa1-x)2O3/Ga2O3 modulation doped field effect transistors

Ultra-wide bandgap β-gallium oxide (Ga2O3) devices are of considerable interest with potential applications in both power electronics and radio frequency devices. However, current Ga2O3 device technologies are limited by the material's low intrinsic electron mobility and thermal conductivity. The former problem can be addressed by employing modulation-doped β-(AlxGa1−x)2O3/Ga2O3 heterostructures in the device architecture. In this work, (AlxGa1−x)2O3/Ga2O3 modulation-doped field effect transistors (MODFETs) have been investigated from a thermal perspective. Thermoreflectance thermal imaging was used to characterize the self-heating of the MODFETs. The (Al0.18Ga0.82)2O3 thermal conductivity (3.1–3.6 W/mK) was determined using a frequency domain thermoreflectance technique. Electro-thermal modeling was used to discern the effect of design parameters such as substrate orientation and channel length on the device self-heating behavior. Various thermal management schemes were evaluated using the electro-thermal device model. From an electro-thermal co-design perspective, the improvement in electrical performance followed by the mitigation of self-heating was also studied. For example, by employing a Ga2O3-on-SiC composite wafer, which was fabricated in this work, a 50% increase in power handling capability can be achieved as compared to a homoepitaxial device. Furthermore, flip-chip heterointegration and double-sided cooling approaches can lead to more than 2× improvement in the power handling capability. Using an augmented double-sided cooling design that includes nanocrystalline diamond passivation, a 5× improvement in the power handling capability can be accomplished, indicating the potential of the technology upon implementation of a suitable thermal management scheme.

Electro-thermal modeling of multifinger AlGaN/GaN HEMT device operation including thermal substrate effects

AlGaN/GaN high electron mobility transistor (HEMT) device operation was modeled from the sub-micrometer scale to the substrate using a combination of an electro-thermal device model for the active device with realistic power dissipation within the device and a coupled three dimensional thermal model to account for the substrate. Temperatures for various points within a device were determined as a function of biasing conditions, substrate thickness and temperature, number of fingers, and gate length and pitch. As an example, we have used our model to show that life test results of industry-relevant devices can be significantly affected by the exact testing technique used.

Circuit-level electrothermal simulation of electrical overstress failures in advanced MOS I/O protection devices

Previous work on electrothermal simulation using network analysis techniques has been of limited use due to the lack of avalanche breakdown modeling capability and the models to efficiently describe the temperature dynamics. Particularly, simulation of electrical overstress (EOS) and electrostatic discharge (ESD), which are important threats to IC reliability, require an accurate description of temperature-dependent device electrical behaviour including breakdown phenomenon. This paper presents electrothermal device models and their implementation in a new circuit-level electrothermal simulator iETSIM. Simulation results for an I/O protection device in an advanced MOS process are presented to demonstrate iETSIM's ability to accurately model device behaviour up to the onset of second breakdown. >