First Demonstration of an Ultra-Wide Bandgap Power Module through Device-Package, Electro-Thermo-Mechanical Co-Optimization

We demonstrate, for the first time, an ultra-wide bandgap (UWBG) power module, which integrates 6 packaged Ga₂O₃ dies and achieves 1000 V and 200 A switching – over 10× higher power capacity than previously reported UWBG devices. To address Ga₂O₃'s low thermal conductivity (k_T), a junction-side-cooling (JSC) package is employed, achieving low thermal resistance. However, JSC package often degrades breakdown voltage (BV) due to high electric fields at the die edges. To overcome this, we introduce two novel interface designs between device surface and the die attach in package: a post interface and a high-κ dielectric interface. The post interface preserves the device's BV by physically distancing high-field regions, while the high-κ interface further enhances BV via polarization effects. In terms of thermal performance, the high-κ design reduces thermal resistance by 50% compared to the post design, while both enable direct JSC. Mechanically, the post provides stress relief by acting as a compliant buffer, and high-κ interface reduces stress by improving coefficients of thermal expansion (CTE) match between Ga₂O₃ and sintered Ag. Such improvements are validated experimentally by power cycling tests. Overall, these electro-thermo-mechanical cooptimizations offer critical guidance for module development in UWBG devices and enable a key milestone in power scaling for UWBG power technologies toward industrial applications. © 2025 IEEE.