First-Principles Study for ALD of MoS2
Additional Funding Sources
The project described was supported by the National Science Foundation via the Research Experience for Undergraduates Site: Materials for Society at Boise State University (Award No. DMR 1658076).
Presentation Date
7-2019
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 (MoF6 and H2S for MoS2) are never introduced simultaneously. In this study, we determined the role of surface hydroxyl groups (-OH) during MoF6 deposition on an Al2O3 surface, and we studied the reactivity of two other potential substrates, Si2N2O and TiO2. 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 MoF6. We see that the MoF6 can reduce to MoF5, MoF4, or MoF3, 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 Al2O3 by strengthening the interactions between Al atoms and F atoms on MoF6.
First-Principles Study for ALD of MoS2
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 (MoF6 and H2S for MoS2) are never introduced simultaneously. In this study, we determined the role of surface hydroxyl groups (-OH) during MoF6 deposition on an Al2O3 surface, and we studied the reactivity of two other potential substrates, Si2N2O and TiO2. 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 MoF6. We see that the MoF6 can reduce to MoF5, MoF4, or MoF3, 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 Al2O3 by strengthening the interactions between Al atoms and F atoms on MoF6.
Comments
W2