Cerium dioxide buffer layers at low temperature by atomic layer deposition

• Published in: Journal of materials chemistry 2002-01, Vol.12 (6), p.1828-1832
• Main Authors: PÄIVÄSAARI, Jani, PUTKONEN, Matti, NIINISTÖ, Lauri
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/b108333c

CeO2 thin films were deposited by atomic layer deposition (ALD). Temperature ranges studied were 175-375 C and 225-350 C for the Ce(thd)4 and Ce(thd)3phen (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate, phen = 1,10-phenanthroline) precursors, respectively. Ozone was used in both cases as an oxygen source. Film thickness, crystallinity and morphology were determined by UV-VIS spectroscopic, XRD and AFM measurements, respectively. Narrow ALD windows, i.e. temperature ranges with constant growth rate, were seen at temperatures of 175-250 C for Ce(thd)4 and 225-275 C for Ce(thd)3phen. The growth rates of CeO2 inside the ALD windows were 0.32 Angstrom/cycle and 0.42 Angstrom/cycle for Ce(thd)4 and Ce(thd)3phen, respectively. CeO2 films grown on soda lime glass and Si(100) were polycrystalline and slightly oriented with the (200) and (111) peaks as the strongest reflections. TOF-ERD analysis of the Ce:O ratio showed that the films were nearly stoichiometric but that they contained hydrogen (7-10 at%), as well as some carbon and fluorine, as impurities. 56 refs.