Structural and Electrical Properties of Atomic Layer Deposited PtRu Bimetallic Alloy Thin Films

Hyun-Jae Woo,Qimin Wang,Woo-Jae Lee,Shihong Zhang,Chang-Min Kim,Se-Hun Kwon,Yong-Jin Yoon

doi:10.3390/coatings12010101

Hyun-Jae Woo, Qimin Wang + Show 5 more

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https://doi.org/10.3390/coatings12010101

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Abstract

The structural and electrical properties of PtRu bimetallic alloy (BA) thin films prepared via atomic layer deposition (ALD) were systemically investigated according to the film composition, which was controlled at a deposition temperature of 340 °C by changing the numbers of Pt and Ru subcycles of a supercycle. As-deposited PtRu BA thin films exhibited weaker crystallinity than Pt36Ru64 when the Ru content was high. However, crystallinity improved, and the peak shifts became clearer after Ar heat treatment at 700 °C, reflecting the formation of well-mixed solid solutions. The electrical resistivity and work function also improved. The work function of PtRu BA thin films can be controlled between the work functions of Pt and Ru, and is only weakly dependent on the film composition in the single solid solution region.

Highlights

Bimetallic alloy (BA) systems allow researchers to discover new properties, or tune existing ones, by changing the nature or proportions of the two elements [1,2,3,4,5]
The equilibrium bulk phase diagram of a Pt-Ru binary system [11] revealed that Pt and Ru can form a very wide range of solid solutions with a face-centered cubic (FCC) structural component of up to ~60 at.% Ru
The broad range over which single FCC and hexagonal close-packed (HCP) solid solution phases can exist in Pt-Ru binary systems facilitates tuning of electrical resistivity and work function

Summary

Introduction

Bimetallic alloy (BA) systems allow researchers to discover new properties, or tune existing ones, by changing the nature or proportions of the two elements [1,2,3,4,5]. The broad range over which single FCC and HCP solid solution phases can exist in Pt-Ru binary systems facilitates tuning of electrical resistivity and work function. Changes in the electronic resistivities, work functions, and the crystal structures of ultra-high vacuum (UHV)-sputtered PtRu BA thin films of various compositions matched the predictions of the equilibrium bulk phase diagram. The work functions of single FCC and HCP solid solution phases were only weakly dependent on the compositions [8]. It allows for a proper material design to obtain similar electrical properties with reduced Pt content

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