Growth and Structural Properties of GeO ₂ on Free-Standing Cubic 3C-SiC Substrates via Mist Chemical Vapor Deposition

Rutile-type germanium dioxide (r-GeO2) is an ultrawide-bandgap semiconductor with ambipolar doping ability. This study examines the mist chemical vapor deposition of GeO2 on (100)-oriented cubic 3C-SiC, motivated by the small lattice mismatch (0.97%) between (001) r-GeO2 and (100) 3C-SiC. However, X-ray diffraction and electron backscattered diffraction (EBSD) analyses revealed that the films consisted of amorphous and polycrystalline α-quartz GeO2, rather than r-GeO2. Scanning electron microscopy images and EBSD inverse pole figure maps suggest random nucleation of α-quartz GeO2, and the diffusion length of adatoms varies with the growth temperature. A variation in the slope of the Arrhenius plot for the growth rate was observed at a growth temperature around 650 °C, indicating a change in the growth mode. These results demonstrate that lattice length matching alone is insufficient to stabilize r-GeO2 and highlight the critical role of the substrate nature in realizing r-GeO2 thin-film growth.