Talk-1: Out-of-SOA Electrothermal Limitations of Power Semiconductor Devices: Characterization and Modelling

Time: 0915 - 0950

Nowadays Wide Bandgap semiconductor devices are getting an increased attention due to some attractive features and superior electrical properties. As the use of these devices is reaching the market, many concerns about their robustness and long term reliability are arising. In this talk, we will focus on the behavior of Silicon carbide power Mosfets during out-of-SOA events such as short circuit or unclamped inductive switching conditions. In the first part of the talk, a detailed approach to self consistent electrothermal simulations of power devices will be given, while in the final part of the talk some results of infrared characterization of short circuit events in power devices will be reported.

Talk-2: GaN Power HEMTs with Ferroelectric Gate Stack for EV and PV Applications

Time: 0950 - 1025

GaN-based high-electron-mobility transistors (HEMTs), which possess high saturation velocity, electron mobility, current density, and breakdown voltage with low resistance, are getting more popular for high-power switching applications. However, their inherent property with normally-on operation is unfavorable for power-switching applications for electric vehicles where safety is paramount. To achieve normal off operation for GaN HEMT devices, several methods have been proposed to achieve a high positive threshold voltage value. This work uses a novel charge storage structure with a hybrid ferroelectric charge-trapping gate stack to realize the GaN E-mode MIS-HEMT with high threshold voltage for EV and PV (> 3.5 V) applications. This gate stack structure combines ferroelectric film with a charge-trapping layer and current-blocking film, resulting in a polarization charge field against the applied gate voltage, and thus achieves a large positive shift of the threshold voltage. The device has a high Vth; meanwhile, low on-resistance, high IDS,MAX, and high breakdown voltage are maintained, perfect for EV and PV applications. The reliability evaluation for these devices will be addressed to facilitate their practical applications in the future.

Talk-3: High-Frequency GaN Based Converters with Integrated Magnetics

Time: 1040 - 1115

The majority of power electronic equipment, with few exceptions, has traditionally been designed and constructed using discrete active and passive components. The power electronics industry has reached a level of maturity where enhancing one performance attribute often comes at the expense of others. Moreover, manufacturing practices have remained labor-intensive and largely unchanged for decades.

The emergence of the new generation of wide-band-gap power semiconductor devices, such as GaN, presents a significant reduction in both conduction and switching losses when compared with their silicon counterparts. Current design practices involving these Wide Band Gap (WBG) devices often adhere to a 'plug-and-play' concept, resulting in incremental improvements in efficiency and power density. However, this approach fails to fully unlock the potential for a transformative paradigm shift in the design and manufacturing process.

This presentation will highlight the potential of combining PCB-based magnetics with GaN power devices to bring about a fundamental shift in design and manufacturing practices. This holistic approach has the capability to simultaneously enhance all performance attributes, encompassing efficiency, power density, cost, and electromagnetic compatibility (EMC). Moreover, the labor-intensive aspects of manufacturing, such as processes related to magnetics and system assembly, can be efficiently streamlined through automation.

Talk-4: Ga₂O₃ Power Device Toward High-Voltage and High-Temperature Applications

Time: 1400 - 1435

Benefitted from progress on the large-diameter Ga₂O₃ wafers and Ga₂O₃ processing techniques, the Ga₂O₃ power device technology has witnessed fast advances. Recently, reports on large-area (ampere-class) Ga₂O₃ power devices have emerged globally, and the scope of these works have gone beyond research device demonstration into device packaging, circuit testing, and ruggedness evaluation. These results have placed Ga₂O₃ in a unique position as the only ultra-wide bandgap semiconductor reaching these indispensable milestones towards commercialization and application.

This talk will first introduce our work on exploring the new application space of Ga₂O₃ devices, particularly towards high-voltage high-temperature applications. By deploying multidimensional architectures, we demonstrated Ga₂O₃ diodes and transistors with breakdown voltage over 10 kV and operational temperatures over 200 ^oC. This talk will then discuss the packaging and robustness of Ga₂O₃ devices. Using the junction-side cooling package, the intrinsic thermal limitations of Ga₂O₃ material can be effectively addressed. The deployment of a unique bipolar heterojunction allows for the demonstration of avalanche and surge current robustness in Ga₂O₃ devices. Overall, the parallel efforts in device development, packaging, and robustness could synergistically propel the Ga₂O₃ technology towards power electronics applications.

Talk-5: Recent Developments in Devices and Modules for Electric Vehicles in the UK

Time: 1435 - 1515

In this talk we will present some the developments in SiC power electronics for automotive applications. This is based on two large UK projects in this space funded by the Advanced Propulsion Centre. These projects were focused on the supply chain for both power devices and 800V inverter development.