Abstract
Grain boundaries (GBs) in metals usually increase electrical resistivity due to their distinct atomic arrangement compared to the grain interior. While the GB structure has a crucial influence on the electrical properties, its relationship with resistivity is poorly understood. Here, we perform a systematic study on the resistivity–structure relationship in Cu tilt GBs, employing high-resolution in situ electrical measurements coupled with atomic structure analysis of the GBs. Excess volume and energies of selected GBs are calculated using molecular dynamics simulations. We find a consistent relation between the coincidence site lattice (CSL) type of the GB and its resistivity. The most resistive GBs are in the high range of low-angle GBs (14°–18°) with twice the resistivity of high angle tilt GBs, due to the high dislocation density and corresponding strain fields. Regarding the atomistic structure, GB resistivity approximately correlates with the GB excess volume. Moreover, we show that GB curvature increases resistivity by ∼80%, while phase variations and defects within the same CSL type do not considerably change it.
Highlights
The electrical resistivity of grain boundaries (GBs) in conductive materials hampers the development of nanoelectronic and energy-harvesting devices
This study focuses on Cu, on the one hand, as a model system that has been investigated with respect to different GB structures, and on the other hand, due to the high application relevance concerning its electronic properties for integrated circuits
Well-defined tilt GBs in Cu are achieved through the deposition of a thin film by magnetron sputtering on a c-plane α-Al2O3 surface, as this is known to create [111] tilt GBs aligned vertical to the surface.[34,35]
Summary
The electrical resistivity of grain boundaries (GBs) in conductive materials hampers the development of nanoelectronic and energy-harvesting devices. The magnitude of the potential wall is associated with the GB structure and its chemical bonding.[13,14] the distinct atomic arrangements at the GB locally change the density of states and electron density compared to the grain interior[15] as confirmed by density functional theory (DFT) simulations.[12,14,16] its experimental observation is challenging because of the difficulties in isolating a specific GB and characterizing solely its resistivity.[13,17,18] cumulative scattering events on the different GBs blur out all details of the influence of GB type and character on resistivity To overcome this challenge, there is a need to probe the electrical resistivity of an individual GB segment. This study, which was Received: July 27, 2021 Accepted: September 28, 2021 Published: October 4, 2021
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