The thermal stability of $\varepsilon$ -Ga 2 O 3 thin films grown on (111) 3C-SiC template substrates

The thermal stability of $\varepsilon$ -Ga 2 O 3 thin films grown on a (111) 3C-SiC template was investigated by X-ray diffraction. C-axis-aligned single-phase $\varepsilon$ -Ga 2 O 3 thin films grown at 350 °C by mist chemical vapor deposition were annealed from 700 to 900 °C in air ambient. The structure of the as-grown $\varepsilon$ -Ga 2 O 3 thin films changed from pure single-phase $\varepsilon$ -Ga 2 O 3 to a mixed-phase with $\varepsilon$ -Ga 2 O 3 and $\beta$ -Ga 2 O 3 after annealing at 850 °C. Furthermore, 900 °C annealing made it completely transit to $\beta$ -Ga 2 O 3 . These results indicated that the thermal stability of the mist-CVD grown $\varepsilon$ -Ga 2 O 3 films is comparable to that of previously reported films grown by other methods. This critical temperature will limit the process temperature for device fabrication, especially for the active region formation by the ion implantation process in order to make satisfactory ohmic contact.