Direct Atomic Layer Deposition of Ultrathin Aluminum Oxide on Monolayer MoS2 Exfoliated on Gold: The Role of the Substrate. Issue 21 (11th October 2021)

• Record Type: Journal Article
• Authors: Schilirò, Emanuela; Nigro, Raffaella Lo; Panasci, Salvatore E.; Agnello, Simonpietro; Cannas, Marco; Gelardi, Franco M.; Roccaforte, Fabrizio; Giannazzo, Filippo
• Is Part Of: Advanced materials interfaces. Volume 8:Issue 21(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-10-11
• Subjects: atomic force microscopy -- atomic layer deposition -- conductive atomic force microscopy -- MoS 2 -- photoluminescence -- Raman spectroscopy; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.202101117
• Languages: English
• ISSNs: 2196-7350

Abstract

Abstract: In this paper, the authors demonstrate the atomic layer deposition (ALD) of highly homogeneous and ultrathin (≈3.6 nm) Al2 O3 films with very good insulating properties (breakdown field of ≈10–12 MV cm −1 ) directly onto monolayer (1L) MoS2 exfoliated on gold. Differently than in the case of 1L MoS2 supported by a common insulating substrate (Al2 O3 /Si), a better nucleation process of the high‐ k film is observed on the 1L MoS2 /Au system since the ALD early stages. Atomic force microscopy analyses show a ≈50% Al2 O3 surface coverage just after 10 ALD cycles, its increase to >90% (after 40 cycles), and a uniform ≈3.6 nm film (after 80 cycles). The Al2 O3 density on bilayer MoS2 is found to be significantly reduced with respect to 1L MoS2 /Au, suggesting a role of screened interface charges with the metal substrate on the adsorption of ALD precursors. Finally, Raman and photoluminescence spectroscopy show a p‐type doping and tensile strain of 1L MoS2 induced by the Au substrate, providing an insight on the evolution of vibrational and optical properties after the Al2 O3 deposition. The direct ALD growth of Al2 O3 on large‐area 1L MoS2 induced by the Au underlayer can be of wide interest for electronic applications. Abstract : The direct atomic layer deposition of Al2 O3 on monolayer (1L) MoS2 supported by gold and by a common insulating substrate (Al2 O3 /Si) is investigated. The growth of compact and ultrathin (≈3.6 nm) Al2 O3 film is obtained on 1L MoS2 /Au, and it is discussed in terms of the peculiar interaction with the metal substrate.