Article pubs.acs.org/JPCC
Effects of Oxygen Incorporation on the Physical Properties of Amorphous Metal Thin Films Sean W. Muir,*,† E. William Cowell,† Wei Wang,† John F. Wager,‡ and Douglas A. Keszler† †
Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331-4003, United States School of Electrical Engineering and Computer Science, Oregon State University, 1148 Kelley Engineering Center, Corvallis, Oregon 97331-5501, United States
‡
S Supporting Information *
ABSTRACT: Incorporated oxygen is known to affect amorphous metal thin film (AMTF) mechanical properties, but comparatively little is known about how it affects their structural characteristics and electrical transport properties. In this study, AMTFs are produced by using sputter deposition. Chemical composition, average interatomic spacing, surface roughness, and electrical transport properties are examined using electron probe microanalysis (EPMA), X-ray diffraction (XRD), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and variable-temperature resistivity. ZrCuAlNi amorphous metal thin films exhibit a temperature dependence that is characteristic of d-electron conduction and electrical resistivity that increases substantially with increasing oxygen content. TiAl and ZrCuB are found to be spelectron conductors with electrical resistivity that decreases with increasing oxygen content. The surface roughness of all films increases with oxygen content, whereas interatomic spacing is relatively insensitive to incorporated oxygen content. The relationships among amorphous metal composition, structural characteristics, and electrical transport properties are discussed.
1. INTRODUCTION The mechanical properties of amorphous metals, such as high strength, hardness, and elasticity have led to their use in macroscale products, e.g., golf-club heads1 and surgical scalpels,2 as well as microscale products, e.g., hinges for digital light processors.3 Additionally, the low magnetic coercivity and large magneto-elastic response of certain amorphous metals has led to their extensive use in electric utility transformer cores and retail antitheft devices.1 The usefulness of amorphous metals also extends to the nanoscale. Bulk metallic glass (BMG) molds, for example, have been used for nanoscale imprinting and embossing4 and amorphous metal thin films (AMTFs) have been employed in the fabrication of 3D micro and nanostructures.5 Unlike an unpolished crystalline metallic thin film, extremely smooth surfaces (surface roughness
