Improved thermal conductivity of Ga2O3 thin films grown on polished polycrystalline diamond by thermal annealing

Since diamonds are the ultimate heat dissipation material, attempts have been made to integrate gallium oxide (Ga2O3) and diamond. Mist chemical vapor deposition is one of several integration approaches used to grow Ga2O3 thin films on polycrystalline diamond templates. The thermal conductivity of the grown Ga2O3 thin film was measured using time-domain thermoreflectance (TDTR). Smoothening of the diamond surface texture was effective in achieving reliable measurement of TDTR. The thermal annealing of Ga2O3 thin film strongly affected the improvement of thermal transport by inducing the smoothness of the grain/grain interface, hardening of grain size, and unification of the crystal phase with crystal ordering. The annealed Ga2O3 thin film, with a thickness of 1-1.5 mu m had a thermal conductivity of 3.54 W/mK, which increased by 48 % compared to the as-grown film. Therefore, in practical applications, this approach may prove beneficial for achieving high heat dissipation in Ga2O3-based devices.