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

• Deposition of Ga 2 O 3 thin films on polycrystalline diamond using mist CVD. • Impact of diamond surface polishing on the oxide film deposition . • Structural change in Ga 2 O 3 films, including polymorphic phases and crystalline grains. • Improved thermal conductivity of Ga 2 O 3 thin films through the annealing process for efficient heat dissipation. Since diamonds are the ultimate heat dissipation material, attempts have been made to integrate gallium oxide (Ga 2 O 3 ) and diamond. Mist chemical vapor deposition is one of several integration approaches used to grow Ga 2 O 3 thin films on polycrystalline diamond templates. The thermal conductivity of the grown Ga 2 O 3 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 Ga 2 O 3 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 Ga 2 O 3 thin film, with a thickness of 1–1.5 μm 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 Ga 2 O 3 -based devices.