MOCVD Growth of -Ga₂O₃ on (001) Ga₂O₃ Substrates

In this study, we comprehensively investigated the growth of beta-Ga2O3 on (001) on-axis Ga2O3 substrates via metalorganic chemical vapor deposition (MOCVD) using both triethylgallium (TEGa) and trimethylgallium (TMGa) as the Ga precursors. For MOCVD growth with TEGa, the group VI/III molar ratio was tuned with different TEGa molar flow rates. The correlation between growth conditions and the surface morphology, growth rate, and electron transport properties of MOCVD-grown (001) beta-Ga2O3 thin films is comprehensively analyzed. Room temperature mobility of 85 cm(2)/V s with carrier concentration of 2.0 x 10(17) cm(-3) was measured for a film grown using the TEGa molar flow rate of 19 mu mol/min and VI/III molar ratio of 934. For MOCVD growth of (001) Ga2O3 using TMGa, we observed the occurrence of cracking along the [010] direction in the grown films, which was found to be closely related to the film thickness and growth rate. The relatively smooth surface morphology of the films with cracks is attributed to the strain relaxation. (001) beta-Ga2O3 films containing rotation domains with (-401) plane were observed from high-resolution X-ray diffraction (XRD) and confirmed with atomic-resolution scanning transmission electron microscopy (STEM) imaging. Under the same growth condition, (001) beta-Ga2O3 films contain higher carbon concentration as compared to that of the (010) beta-Ga2O3 films. Results from this work provide fundamental insights into the MOCVD epitaxy of beta-Ga2O3 on (001) Ga2O3 substrates, revealing the opportunities and challenges of MOCVD growth of (001) beta-Ga2O3 thin films with fast growth rates for high-power electronic device technology.