Epitaxial Technologies for Gallium Oxide Ultra High Voltage Power Electronics

xß-Ga2O3 has emerged as a potentially disruptive semiconductor with a predicted breakdown field of ~8 MV/cm which is more than twice the breakdown field for the incumbent wide bandgap semiconductors GaN and SiC. The availability of ß-Ga2O3 bulk substrates sets this material apart from other wide bandgap materials for power electronic applications. However, the challenge is to find suitable epitaxial film growth techniques that allows fast growth rates and reasonable p- and n-type doping. In Phase I, we used virtual reactor modeling to identify suitable precursors and reactor geometries for fast growth rates. Actual film growth using close coupled showerhead MOCVD was also conducted and ß-Ga2O3 thin film with growth rate up to 9.8 µm/hr was obtained. In Phase II, we will continue to build on our achievements in Phase I and study all aspects of ß-Ga2O3 MOCVD growth processes including precursor types, process dynamics, reactor designing and building. The final MOCVD reactor will incorporate in situ characterization tools and control software, and be capable of growing at a minimum 4 µm/hr. With this reactor, both thick (> 30µm), n-type Ga2O3 drift layers and n- or p-type doped device layers (< 100nm) can be achieved in the same growth run.