Heterogenous integration of gallium oxide with diamond and SiC

Gallium Oxide (Ga₂O₃) has attracted great attention due to its predicted high critical electric field, and consequentially its expectation to have impact for high voltage power devices. However, from a device design and reliability perspective, it has certain drawbacks: Ga₂O₃ has a relatively low thermal conductivity, potentially causing excessively high device temperatures, accelerating device degradation; usable p-doping is unavailable, preventing the use of advanced devices designs such as superjunctions which require both n- and p-doping. It is critically important to address these limitations for Ga₂O₃ to compete with SiC which is Ga₂O₃'s direct competitor, where advanced device concepts such as superjunctions are in process being explored, and prototype devices have already been realized. For Ga₂O₃, one possible solution is heterogeneous integration with other wide or ultra-wide bandgap materials which can be p-doped. Selecting materials with higher thermal conductivity would also address thermal management. Nickel Oxide has been explored as a p-type material and successful Gallium Oxide / Nickel Oxide high voltage proto-type devices have been demonstrated. However, Nickel Oxide's has a low thermal conductivity, so enabling devices which can handle high current densities may be a challenge. Based on these criteria, diamond and SiC are primary candidates for integration with Ga₂O₃. We report here on integration by metal organic chemical vapor deposition (MOCVD) of Ga₂O₃ with diamond and SiC. We also explore direct bonding as an alternative heterogenous integration method.