Process Control of Atomic Layer Deposition Molybdenum Oxide Nucleation and Sulfidation to Large-Area MoS
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Grossman_Process control.pdf
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Author(s)
Bertuch, Adam
Provine, J.
Sundaram, Ganesh
Ferralis, Nicola
Grossman, Jeffrey C.
Keller, Brent D.
Date Issued
March 2017
Journal
Chemistry of Materials
Publisher
American Chemical Society (ACS)
Citation
Keller, Brent D. et al. “Process Control of Atomic Layer Deposition Molybdenum Oxide Nucleation and Sulfidation to Large-Area MoS2 Monolayers.” Chemistry of Materials 29, 5 (February 2017): 2024–2032 © 2017 American Chemical Society
Version
Author's final manuscript
Abstract
Recent advances in the field of two-dimensional (2D) transition metal dichalcogenide (TMD) materials have indicated that atomic layer deposition (ALD) of the metal oxide and subsequent sulfidation could offer a method for the synthesis of large area two-dimensional materials such as MoS 2 with excellent layer control over the entire substrate. However, growing large area oxide films by ALD with sub 1 nm nucleation coalescence remains a significant challenge, and the necessary steps are unexplored. In this work, we demonstrate the necessary process improvements required to achieve sub 1 nm nucleation control by characterization of nucleation domains formed by oxide deposition. Synthesis of the TMD MoS 2 from sulfidation of oxide deposited by both thermal ALD from (tBuN) 2 (NMe 2 ) 2 Mo and O 3 and plasma enhanced ALD (PEALD) from (tBuN) 2 (NMe 2 ) 2 Mo and remote O 2 plasma was performed. Large uniform MoS 2 areas were achieved by optimizing the effects of various growth process conditions and surface treatments on the ALD nucleation and growth of Mo-oxide and the postsulfidation of MoS 2 . In addition to insights into the control of the oxide deposition, film chemistry analysis during a multistep sulfidation based on less toxic sulfur as compared to H 2 S was performed for several temperature profiles revealing sulfur incorporation and molybdenum reduction at low temperatures but higher temperatures required for 2H crystal structure formation. The knowledge gained of the ALD, PEALD, and postsulfidation was leveraged to demonstrate tunable film thickness and centimeter-scale monolayer growth. Material quality can be studied independently of the MoS 2 layer count as demonstrated by the control of the monolayer photoluminescence intensity by the temperature ramp rate during sulfidation.
MIT Department
Massachusetts Institute of Technology. Center for Materials Science and Engineering
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DOI of Published Version
https://doi.org/10.1021/ACS.CHEMMATER.6B03951
