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

5 years ago

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

Cheol Seong Hwang, Jung Hwan Yum, Sangtae Kim, Eric S. Larsen, Seong Keun Kim, Cheol Jin Cho, Christopher W. Bielawski, Woo Chul Lee

Growth characteristics and properties of BeO films grown by atomic layer deposition (ALD) are investigated. ALD chemistries between dimethylberyllium and two different oxygen sources, H₂O and O₃, 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 H₂O are temperature-independent. In contrast, the BeO films grown using O₃ 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 O₃ 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 H₂O, which show high values of E_g ∼ 9.1–9.4 eV and ε_r ∼ 8. Collectively, these findings demonstrate that the O₃–ALD process requires relatively more thermal energy than H₂O–ALD does, to produce high-quality BeO films.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b05240

DOI: 10.1021/acs.jpcc.7b05240