High-Mobility MOCVD β-Ga₂O₃ Epitaxy with Fast Growth Rate Using Trimethylgallium

Abstract

In this work, metalorganic chemical vapor deposition (MOCVD) of (010) β-Ga2O3 with fast growth rates was investigated using trimethylgallium (TMGa) as the gallium (Ga) precursor. Key growth parameters including precursor/carrier gas flow, growth temperature, chamber pressure, and group VI/III molar flow ratio were systematically mapped. Surface morphology and charge transport properties of the homo-epi (010) β-Ga2O3 thin films were probed to correlate with the crystalline quality. The growth rate of (010) β-Ga2O3 thin film increases as the TMGa flow rate increases, and high-quality epi-film is achievable with a fast growth rate up to ∼3 μm/h. By tuning the n-type dopant silane flow rate, the net charge carrier concentration was tuned from ∼1016 to 1019 cm–3. Room-temperature mobility as high as 190 cm2/V·s was measured for a sample grown with a growth rate of 2.95 μm/h and an electron concentration of 1.8 × 1016 cm–3. Temperature-dependent Hall measurement revealed a peak mobility value of ∼3400 cm2/V·s at 53 K. The extracted low compensation level of NA ∼ 1.5 × 1015 cm–3 indicates the high purity of the MOCVD growth of the (010) β-Ga2O3 film using TMGa as the Ga precursor. Quantitative secondary-ion mass spectroscopy characterization revealed a relatively high C concentration of 7 × 1016 cm–3, indicating that C does not serve as a compensator or a donor in MOCVD grown β-Ga2O3. The results from this study demonstrate the feasibility to grow high-quality Ga2O3 thin films with fast growth rates, critical for developing high power electronic device technology.