Extremely Low Thermal Resistance of β-Ga₂O₃ MOSFETs by Co-integrated Design of Substrate Engineering and Device Packaging

Gallium oxide (Ga₂O₃) emerges as a promising ultrawide bandgap semiconductor, which is expected to surpass the performance of current wide bandgap materials, like GaN and SiC, in electronic devices. However, widespread application of Ga₂O₃ is hindered by its extremely low thermal conductivity and lack of effective device-level thermal management strategies. In this work, Ga₂O₃ metal-oxide-semiconductor field-effect transistors (MOSFETs) are fabricated by conducting co-integrated design of substrate engineering with layer transferring and device packaging. 3D Raman thermography is introduced as a novel method to analyze the temperature distribution within the device, which provides valuable insights into their thermal performances. A high-quality Ga₂O₃-SiC heterogeneous integrated material is successfully fabricated with an extremely low interface thermal resistance of 6.67 ± 2 m²·K/GW. Compared to the homoepitaxial Ga₂O₃ MOSFETs, the degradation of <i>I</i>_on/<i>I</i>_off in Ga₂O₃-SiC MOSFETs is decreased by 1.5 orders of magnitude, and that of <i>R</i>_on is decreased by 31%, showing the great thermal stability of Ga₂O₃-SiC MOSFETs. With the additional device packaging, a significant one order-of-magnitude reduction in the thermal resistance of the Ga₂O₃-SiC MOSFET is achieved, reaching a record-low value of 4.45 K·mm/W in the reported Ga₂O₃ MOSFETs. This work demonstrates an efficient strategy for device-level thermal management in next-generation Ga₂O₃ power and RF applications.