The thermal stability of ε-Ga2O3 thin films grown on (111) 3C-SiC template substrates

The thermal stability of epsilon-Ga2O3 thin films grown on a (111) 3C-SiC template was investigated by X-ray diffraction. C-axis-aligned single-phase epsilon-Ga2O3 thin films grown at 350 degrees C by mist chemical vapor deposition were annealed from 700 to 900 degrees C in air ambient. The structure of the as-grown epsilon-Ga2O3 thin films changed from pure single-phase epsilon-Ga2O3 to a mixed-phase with epsilon-Ga2O3 and beta-Ga2O3 after annealing at 850 degrees C. Furthermore, 900 degrees C annealing made it completely transit to beta-Ga2O3. These results indicated that the thermal stability of the mist-CVD grown epsilon-Ga2O3 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.