Recent Advances in the Growth of Metals, Alloys, and Multilayers by Surface Limited Redox Replacement (SLRR) Based Approaches

Abstract

A B S T R A C TIn the realm of ever increasing importance of nanotechnology, the deposition of ultrathin metal/alloy layers with perfect structure and unique functionality becomes an objective of paramount importance. In the last decade many research groups have been working on the development and application of a new method for epitaxial thin film growth that employs a surface limited redox replacement (SLRR) as a building block reaction. The multiple repetition of this reaction enables the controlled deposition of a monolayer of metal or alloy per cycle. Work in the field has been done on the development of SLRR deposition protocols along with understanding and modelling of the SLRR reaction kinetics, on comparative studies of SLRR based routines, and on other deposition approaches. Most recently, the development of SLRR was extended to the application of all-electroless approaches for carrying out the SLRR (ESLRR). In this paper an overview of all SLRR, ESLRR and related approaches is presented. The description of the background and reaction formalism introduces the method with emphasis on its general applicability and limitations. The discussion then continues with the description of experimental approaches for carrying out a deposition process by SLRR. In this section specific consideration is given to the deposition by shuttling of the working electrode, the flow-cell configuration, the one-cell configuration, and the all-electroless approaches for realizing the repetitive application of a single-cycle SLRR reaction. Next, the ability of these approaches to produce epitaxial, flat and uniform deposits will be discussed through results of electrochemical, in-situ scanning tunneling microscopy, X-ray Photoelectron Spectroscopy and other characterization experiments showing advantages and limitations of SLRR growth in a variety of systems classified into three categories. In the first of these categories Cu, Ag, and Au are used as model systems to introduce the deposition by SLRR. In the second category Pd and Ru deposition by SLRR has been discussed. In the third category all studies concerning a variety of scenarios for Pt deposition by SLRR are presented and in the last part of that section deposition of alloys and multilayers is critically discussed. The paper then continues with a section presenting and discussing modelling approaches of studying the kinetics of a single-cycle SLRR reaction and concludes with the presentation of the extension of modelling to a system where multi-cycle SLRR deposition processes have been investigated. The analysis in this part focuses on the kinetic parameters of the replacement reaction like rate constant, order of the reaction, type of adsorption behavior of the sacrificial metal etc. Finally, this section concludes with a discussion of the mechanistic aspects of the SLRR reaction and more specifically on the factors impacting the deposition process and in turn the resulting structure, morphology, uniformity and continuity of the accordingly grown thin films. The paper a...

Editors' Choice—Reaction Kinetics of Metal Deposition via Surface Limited Redox Replacement of Underpotentially Deposited Monolayer Studied by Surface Reflectivity and Open Circuit Potential Measurements

“…The very details of these three protocols and their applications have been discussed elsewhere in the literature. 4,5,10 Still, more work is necessary to unravel the controlling phenomena of this deposition method and to properly define optimum conditions at which the true benefits of this method are fully exploited.…”

“…This will open new applications of this method in broad spectrum of scales from laboratory experiments to industrial synthesis of core-shell catalysts or wafer level ultrathin thin film growth technologies. 3,4,6,19 Presented work studies the relation between kinetics of metal deposition via SLRR of UPD ML and experimental parameters of the SLRR reaction. The focus is to evaluate the fundamental effects of concentration of: a) UPD metal ions, b) depositing metal ions, and c) supporting electrolyte, on SLRR reaction kinetics.…”

“…[2][3][4] The main idea is to use an UPD ML as sacrificial material to reduce/deposit a more noble metal (SLRR reaction i.e. galvanic displacement).…”

“…The very details of these three protocols and their applications have been discussed elsewhere in the literature. 4,5,10 Still, more work is necessary to unravel the controlling phenomena of this deposition method and to properly define optimum conditions at which the true benefits of this method are fully exploited.In many applications concerned with deposition of only a single monolayer of P or ultra-thin films such as core-shell catalyst synthesis for example 2,3,6 (P = Pt, Pd), the properties of deposited films are * Electrochemical Society Student Member. * * Electrochemical Society Member.…”

Electrochemical Atomic Layer Deposition of Cobalt Enabled by the Surface-Limited Redox Replacement of Underpotentially Deposited Zinc

“…Over the last two decades, electrochemical ALD (or e-ALD) has been utilized for deposition of a variety of metals, 23,24 including Pt, [25][26][27][28] Cu, [29][30][31] Pd, 32 Ru, 33 Ag, [34][35][36] Au, 37 Ge, 38 and semiconductor compounds. [39][40][41] In the following introductory discussion, the process of e-ALD of Cu is described as a representative example.…”