Tuesday, February 23, 2021

Thermal Atomic Layer Deposition of Gold: Mechanistic Insights, Nucleation, and Epitaxy

Here is a new paper with deep insights into thermal ALD of gold from Argonne National Lab in the USA. They are using the previously developed precursor from Mikko Titalas ALD group at Helsinki University Finland Me2Au(S2CNEt2). All depositions were carried out in a Veeco CNT Savannah reactor.

Thermal Atomic Layer Deposition of Gold: Mechanistic Insights, Nucleation, and Epitaxy

Pengfei Liu, Yuchen Zhang, Cong Liu, Jonathan D. Emery, Anusheela Das, Michael J. Bedzyk,
Adam S. Hock*, and Alex B. F. Martinson*
ACS Appl. Mater. Interfaces 2021, XXXX, XXX, XXX-XXX
Publication Date:February 9, 2021https://doi.org/10.1021/acsami.0c17943

An in situ microbalance and infrared spectroscopic study of alternating exposures to Me2Au(S2CNEt2) and ozone illuminates the organometallic chemistry that allows for the thermal atomic layer deposition (ALD) of gold. In situ quartz crystal microbalance (QCM) studies resolve the nucleation delay and island growth of Au on a freshly prepared aluminum oxide surface with single cycle resolution, revealing inhibition for 40 cycles prior to slow nucleation and film coalescence that extends over 300 cycles. In situ infrared spectroscopy informed by first-principles computation provides insight into the surface chemistry of the self-limiting half-reactions, which are consistent with an oxidized Au surface mechanism. X-ray diffraction of ALD-grown gold on silicon, silica, sapphire, and mica reveals consistent out-of-plane oriented crystalline film growth as well as epitaxially directed in-plane orientation on closely lattice-matched mica at a relatively low growth temperature of 180 °C. A more complete understanding of ALD gold nucleation, surface chemistry, and epitaxy will inform the next generation of low-temperature, nanoscale, textured depositions that are applicable to high surface area supports.

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