Abstract
Atomic layer deposition (ALD) is a method for thin-film growth with atomic thickness control, with many applications in microelectronics. ALD is a cyclical process where the two precursors (MoF 6 and H 2 S for MoS 2 ) are never introduced simultaneously. In this study, we determined the role of surface hydroxyl groups (-OH) during MoF 6 deposition on an Al 2 O 3 surface, and we studied the reactivity of two other potential substrates, Si 2 N 2 O and TiO 2 . We used density functional theory (DFT) implemented by the Vienna ab Initio Simulation Package (VASP) to determine ground-state geometries and electron distributions of our modeled systems. Our results indicate that hydroxyl groups break the Al-O bonds, allowing the Al atoms to bond covalently with F atoms on MoF 6 . We see that the MoF 6 can reduce to MoF 5 , MoF 4 , or MoF 3 , and these reduced oxidation states (+5, +4, or +3 respectively) may improve the deposition process. These results indicate that hydroxyl groups directly control the surface properties of Al 2 O 3 by strengthening the interactions between Al atoms and F atoms on MoF 6 .
Original language | American English |
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State | Published - 12 Jul 2019 |