Influence of Oxygen on β-Ga2O3 Films Deposited on Sapphire Substrates by MOCVD

In this paper, β-Ga2O3 films were deposited on c-plane sapphire substrates by metal-organic chemical vapor deposition. The impact of oxygen flow rate on crystalline quality, surface morphology, optical transmittance, and growth rate were systematically investigated. X-ray diffraction revealed that β-Ga2O3 films preferentially grew along (−201) crystal plane family when grown on sapphire substrates, and the full-width at half maximum indicated that the crystal quality of β-Ga2O3 film was improved by increasing the oxygen flow rate. The oxygen flow rate greatly influenced the surface morphology and growth rate, and the optical band gaps of β-Ga2O3 films deposited at 1500, 1800, 2100, 2400, 2700, and 3000 sccm were 4.88, 4.99, 4.97, 4.97, 4.93, and 4.68 eV, respectively. The photodetectors made of these β-Ga2O3 films also showed that the photo-dark current ratio gradually increased with the increasing oxygen flow rate at 2100 ∼ 2700 sccm, indicating that the crystalline quality of these β-Ga2O3 films improved.