(Invited) Thermal Characterization of Ultra-Wide Bandgap Gallium Oxide Electronics

Abstract

To extend further the electrical performance envelope of wide bandgap (WBG) power and radio frequency (RF) electronics based on gallium nitride (GaN) and silicon carbide (SiC), device engineers are actively pursuing the development of generation-after-next ultra-wide bandgap (UWBG) devices. At the time being, aluminum gallium nitride (AlGaN), β-gallium oxide (Ga2O3), and diamond are technologically relevant UWBG materials that have bandgaps larger than that for GaN (3.4 eV). In particular, the availability of melt-grown substrates for the Ga2O3 materials system offers a clear economic advantage over SiC and GaN device technologies. While UWBG Ga2O3 devices are built to operate under higher power densities compared to current state-of-the-art WBG counterparts, the thermal conductivity Ga2O3 is lower than those for GaN and SiC by an order of magnitude. Therefore, self-heating is a major challenge for devices based on this materials system. Electro-thermal interactions that lead to self-heating in Ga2O3 devices need to be accurately assessed and understood to accomplish the successful transition from WBG devices to the UWBG technology. In this work, we will demonstrate the use of an integrated optical thermography scheme (Raman thermometry, thermoreflectance imaging, and infrared thermography) to study the steady-state and transient thermal characteristics of Ga2O3 Schottky Barrier Diodes (SBD) and lateral Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFET). In addition, we will report our recent progress on the development of a 2-D transducer-assisted Raman thermography technique suitable for Ga2O3 devices, which overcomes limitations associated with current state-of-the-art methods.