Atomic Layer Depositionof Ga2O3Films Using Trimethylgallium and Ozone.

In this manuscript, we demonstrate a new process forthe atomiclayer deposition (ALD) of gallium oxide (Ga2O3) thin films using trimethylgallium (TMGa) and ozone. We evaluateda variety of oxygen sources for Ga2O3ALD usingTMGa but found that only ozone was effective. We explored the mechanismfor Ga2O3ALD using in situ quartz crystal microbalance,Fourier transform infrared spectroscopy, and quadrupole mass spectrometrystudies. We found that TMGa dissociatively adsorbs onto the Ga2O3surface to form Ga(CH3)2surface species and liberate ∼20% of the methyl ligands asCH4. Next, the ozone reacts with these methyl species toform hydroxyl and formate surface groups and liberate CH2O. We prepared ALD Ga2O3films on Si(100) andfused SiO2substrates and analyzed the films using a varietyof techniques. We found the Ga2O3growth tobe self-limiting with a growth rate of ∼0.52 Å/cycle between200 and 375 °C. Moreover, the Ga2O3filmswere stoichiometric, free of residual carbon, and exhibited propertiessimilar to bulk Ga2O3. Scanning electron microscopyrevealed smooth films with good step coverage over trench structures,and X-ray diffraction showed that the films were amorphous as-depositedbut crystallized to β-Ga2O3upon annealingat 900 °C. [ABSTRACT FROM AUTHOR]