Adsorption Processes during Electrochemical Atomic Layer Deposition of Gold. Issue 11 (8th November 2021)

• Record Type: Journal Article
• Authors: Wasalathanthri, Ruwani N.; Gong, Yukun; Biener, Monika M.; Ivanovskaya, Anna N.; Dudukovic, Nikola A.; Akolkar, Rohan
• Is Part Of: Journal of the Electrochemical Society. Volume 168:Issue 11(2021)
• Publication Date: 2021-11-08
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ac3310
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Electrochemical atomic layer deposition (e-ALD) technique offers a simple and effective "wet chemistry" approach enabling high-precision monolayer-by-monolayer deposition of metal films. The process of e-ALD of Au involves lead underpotential deposition (PbUPD ) followed by its redox replacement by a Au monolayer. The time evolution of the deposit mass during "one-pot" Au e-ALD is known to exhibit a unique three-stage response that is presently not well understood. In this work, we probe this response using voltammetry, electrochemical quartz crystal microgravimetry (e-QCM), and chronoamperometry to unravel the underlying mechanistic events during Au e-ALD. The presence of adsorbed Au +3 -ligand complex(es) (Au-L) on the Au surface is established. In stage I of e-ALD, this Au-L adsorbed layer is reduced to Au while a PbUPD adlayer is formed. In stage II, the PbUPD adlayer undergoes spontaneous surface-limited redox replacement by nobler Au under open-circuit conditions. Finally, in stage III, re-adsorption of the Au-L occurs on the newly deposited Au. Quantitative analysis of the deposit mass transients obtained under a variety of conditions provides an estimate of the Au-L mass and its molecular weight.