(Electrodeposition Division Research Award Address) Metal Deposition Assisted by UPD Monolayers-Fundamentals and Applications

Wednesday, 4 October 2017: 14:00
Chesapeake H (Gaylord National Resort and Convention Center)
S. R. Brankovic (University of Houston, Houston, Texas)
The improved understanding of nucleation and growth kinetics provided the base for design of new experimental approaches where the thin film growth was manipulated to enhance the evolution of atomically flat epitaxial overlayers. Following this progress, a new protocols for electrochemical thin film growth were developed which benefit from the Underpotentially Deposited Monolayers (UPD ML) serving as a surfactants (Surfactant Mediated Growth, SMG), mediators (Defect Mediated Growth, DMG) or sacrificial materials (Deposition via Surface Limited Redox Replacement, SLRR) in electrodeposition process of thin films. In these examples, the essential step that results in desired 2D growth mode is achieved by precise control of the electrode potential, electrodeposition sequence and/or solution chemistry which enable particular action/benefit of the UPD ML to be fully exploited in the growth process.

In the first part of the talk we will briefly review fundamentals of the electrochemical thin film growth assisted by UPD ML. Our results and discussion are focused on examining the extendibility of SMG, DMG and SLRR approach for thin film growth in technologically relevant system such as Cu/Ru(hklm). The Cu/Ru(hklm) represents the overlayer/substrate system which has significant epitaxial strain (-5.5%). This fact together with room temperature growth conditions favor a 3D growth. However, as it will be shown, with convenient use of UPD ML serving as surfactant, or mediator, or sacrificial material a 2D growth of Cu on Ru can be achieved readily.

In the second part of the talk we will demonstrate that UPD-like ML can be deposited on different substrates using an electroless (e-less) approach. The example of improved morphology and magnetic properties of e-lessly deposited Co overlayers on Cu assisted by e-lessly deposited Pb ML serving as surfactant are analyzed. The phenomenon of e-less UPD-like ML deposition as a prelude for e-less atomic layer epitaxial deposition (E-less ALD) will be discussed as well. We will show results demonstrating noble metal thin film growth on Cu and other substrates using e-lessly deposited Pb UPD-like ML serving as a reducing precursor in SLRR reaction with noble metal ions such as Pt, Pd, and Ru. In conclusion of the talk, (if time permitted), the results from exploratory research studying the benefit of UPD ML serving as a stress moderators in electrodeposition process of Pd thin films will be discussed.

The author acknowledges support from Lam Research Corporation and NSF Chemistry division under the contract # 0955922 and #1605331.