Growth and Characterization of BeO Thin Films Grown by Atomic Layer Deposition Using H₂O and O₃ as Oxygen Sources

Growth characteristics and properties of BeO films grown by atomic layer deposition (ALD) are investigated. ALD chemistries between dimethylberyllium and two different oxygen sources, H 2 O and O 3, are governed by different reaction mechanisms, resulting in different film properties. At growth temperatures ranging from 150 to 300 °C, the properties of the BeO films grown using H 2 O are temperature-independent. In contrast, the BeO films grown using O 3 at low temperatures (<200 °C) show high concentrations of carbon and hydrogen, possibly owing to the incomplete removal of the ligands of the precursor, leading to a low film density. This correlates with the evolution of the rough surface and the microstructure composed of few nanometer-sized grains. The low-quality BeO films grown using O 3 at low temperatures (<200 °C) show a decreased band gap ( E g: 7.7–7.9 eV) and dielectric constant (ε r: 5.6–6.7). Above 250 °C, these properties recovered to the levels ( E g ∼ 9.4 eV and ε r ∼ 8.1) of the BeO films grown using H 2 O, which show high values of E g ∼ 9.1–9.4 eV and ε r ∼ 8. Collectively, these findings demonstrate that the O 3 –ALD process requires relatively more thermal energy than H 2 O–ALD does, to produce high-quality BeO films.