13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Electrical Breakdown of a Metallic Nanowire Mesh Yuan Li1,*, Kaoru Tsuchiya1, Hironori Tohmyoh1, Masumi Saka1 1 Department of Nanomechanics, Tohoku University, Sendai 980-8579, Japan * Corresponding author: liyuan@ism.mech.tohoku.ac.jp Abstract The electrical breakdown of a metallic nanowire mesh induced by Joule heating (i.e., melting) is investigated by solving the corresponding electro-thermal problem, where the effect of electromigration is neglected. A numerical computational program is firstly developed to simulate the temperature profile for a metallic wire mesh and investigate the melting current triggering the melting of mesh segment. The melting process of the mesh structure is investigated by analyzing the variation of melting current with regard to the melting propagation of mesh segment. On this basis, the melting behavior of a system of the mesh equipped with current source is predicted. For both current-controlled and voltage-controlled current source, local instability (i.e., at a constant current/voltage, several mesh segments melt simultaneously) and stable melting (i.e., the increase of current/voltage is necessary for the melting of mesh segment) will happen. Moreover, global instability (i.e., at a constant current, several mesh segments melt until the circuit of mesh opens) will occur only at the mode of current-controlled current source. Keywords Electrical breakdown, Instability, Joule heating, Metallic nanowire mesh, Stable melting, 1. Introduction With one-dimensional structure and nanometer-scale diameter, metallic nanowires have shown remarkable electrical, mechanical, optical and chemical properties [1]. Successful assembly of these metallic nanowires into a mesh structure has offered great potential as components for large-scale integrated devices in nanoelectronics and photonics. Recent reports have shown that such mesh can play new roles which are far from the potential of individual nanowires, including transparent conductors, low-cost flexible electronics [2, 3]. It is well known that if an electrically conductive material is subjected to current flow, Joule heating occurs [4]. Joule heating in these metallic nanowires may go beyond degrading the electrical performance of the corresponding metallic nanowire mesh, and therefore deteriorate the reliability of the mesh-based devices. In order to turn around this problem, clarifying the electrical breakdown of a metallic nanowire mesh induced by Joule heating becomes urgent. Up to date, the electrical breakdown of an individual metallic nanowire has been investigated systematically including melting due to Joule heating [5, 6] and due to electromigration [7-10]. The former has been used to cut metallic nanowire in any desirable length [5, 6] for specific purpose, and the latter has been employed to make the nanogap [7, 8] between metal electrodes into which individual molecules can be inserted to measure their electrical properties. However, little is currently known regarding the electrical breakdown of a metallic nanowire mesh, which is expected to show different characteristics because of its unique mesh structure. In this work, the electrical breakdown of a metallic nanowire mesh induced by Joule heating (i.e., melting) is investigated for the first time. To deal with this type of electro-thermal problem, a numerical simulation method is proposed to determine the associated temperature field for a metallic wire mesh and the variation of the melting current triggering the melting of mesh segment with the melting propagation of mesh segment. By employing the developed computational program, the melting process of a silver (Ag) nanowire mesh structure is clarified by analyzing the variation of melting current during the melting propagation in the mesh. It then indicates the interesting characteristics of the melting behavior for a system of the mesh equipped with current source.
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