Improving the Heat Dissipation and Current Rating of Ga2O3 Schottky Diodes by Substrate Thinning and Junction-Side Cooling

Gallium oxide (Ga2O3) is attractive as a material for power electronics but its low thermal conductivity has risen concerns about thermal management problems. This article provides a direct evaluation of different assembly strategies for Ga2O3 Schottky diodes. 600 mu m thick (current standard) and novel 200 mu m thin large-area beta-Ga2O3 diodes are assembled on ceramic substrates in cathode-side cooled and junction-side cooled (JSC) configuration, and compared to a commercial SiC reference diode of similar size that was assembled in the same way, which enables a fair comparison. Thermal imaging and measurements of the thermal structure functions reveal the different contributions of die and package to the total thermal resistance. The lowest junction temperature, close to that of the SiC counterpart, is achieved with JSC. By combining the measurements with thermal simulations, it is shown that an optimization of the die attach thickness or the use of underfill materials in JSC configuration could further lower the average junction temperature and decrease local temperature peaks significantly. The influence of the assembly method, substrate thickness, and on-resistance on the power and current rating of the Ga2O3 diodes is discussed for applications where conduction losses dominate.

Automated summary

This article evaluates different assembly strategies for Gallium oxide (Ga2O3) Schottky diodes and discusses the influence of substrate thickness, on-resistance, and assembly method on the power and current rating of the diodes. It also shows that optimizing the die attach thickness or using underfill materials in a specific configuration can reduce the average junction temperature and local temperature peaks.