Molecular Level Insights into Atomic Layer Deposition of CdS by Quantum Chemical Calculations

• Published in: Journal of physical chemistry. C 2010-10, Vol.114 (39), p.16618-16624
• Main Authors: Tanskanen, Jukka T, Bakke, Jonathan R, Bent, Stacey F, Pakkanen, Tapani A
• Format: Article
• Language: English
• Subjects: C: Surfaces, Interfaces, Catalysis
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp105911p

Growth characteristics of cadmium sulfide atomic layer deposition (ALD) from dimethylcadmium (DMCd) and hydrogen sulfide have been investigated by hybrid DFT and MP2 calculations. The steady-state film growth during one ALD cycle was modeled by studying dissociative chemisorption of the dimethylcadmium precursor on the sulfur-terminated (111) surface of zincblende CdS and then by investigating the chemisorption of hydrogen sulfide on the surface formed due to the treatment with the Cd reactant. The calculated reaction barriers for the ALD half reactions suggest that elevated temperatures are required for the film growth. Periodic calculations provide evidence for submonolayer growth per ALD cycle and suggest that steric factors prevent full monolayer formation during DMCd exposure, whereas all adsorption sites are likely to react during the hydrogen sulfide pulse.