Monolithic on-chip integration of micro-thin film thermocouples on multifinger gallium oxide MOSFETs

Abstract

Gallium oxide (Ga2O3), with its ultra-wide bandgap (>4.5 eV), is a key material for the next-generation power electronics due to its high breakdown voltage and efficient power-switching capabilities. Multifinger (MF) Ga2O3 MOSFETS, designed to enhance current handling and thermal management, experience significant self-heating effects that can lead to localized hotspots, thermal runaway, and reduced device reliability. Accurate thermal characterization is therefore critical to ensure the reliable operation and longevity of such devices. Conventional methods, such as thermoreflectance imaging, Raman thermometry, and infrared thermography, are limited by complex setups, slow response times, resolution constraints, and cost, making them less practical for real-time, on-chip applications. On-chip thermal characterization directly at the active regions of the device provides an unparalleled opportunity to overcome these limitations by capturing localized temperature variations during operation. In this study, we demonstrate the integration of micro-thin film thermocouples (micro-TFTCs) onto multifinger Ga2O3 MOSFETs for precise, real-time, and localized thermal monitoring. The sensors captured temperature variations across different gate fingers, with the measured maximum channel temperature reaching 40.5 °C under peak power dissipation. Predicted thermal behavior under high power densities shows temperatures rising to approximately 80 °C at 5 W/mm2, illustrating the thermal challenges faced by Ga2O3 devices. This work demonstrates that micro-TFTCs are not only compatible with complex device architectures but also highly effective for localized thermal characterization, making them a promising tool for improving the thermal management and reliability of Ga2O3-based power electronics.