The Contact Resistance Performance of Gold Coated Carbon-Nanotube Surfaces under Low Current Switching

John W. McBRIDE  Chamaporn CHIANRABUTRA  Liudi JIANG  Suan Hui PU  

IEICE TRANSACTIONS on Electronics   Vol.E96-C    No.9    pp.1097-1103
Publication Date: 2013/09/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E96.C.1097
Print ISSN: 0916-8516
Type of Manuscript: Special Section INVITED PAPER (Special Section on Recent Development of Electro-Mechanical Devices — Papers selected from International Session on Electro-Mechanical Devices 2012 (IS-EMD2012) and other recent research results —)
carbon nanotubes,  contact surface,  MEMS switching surface,  fine transfer mechanism,  contact resistance,  

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Multi-Walled CNT (MWCNT) are synthesized on a silicon wafer and sputter coated with a gold film. The planar surfaces are mounted on the tip of a piezo-electric actuator and mated with a gold coated hemispherical surface to form an electrical contact. These switching contacts are tested under conditions typical of MEMS relay applications; 4V, with a static contact force of 1mN, at a low current between 20-50mA. The failure of the switch is identified by the evolution of contact resistance which is monitored throughout the switching cycles. The results show that the contact resistance can be stable for up to 120 million switching cycles, which are 106 orders of higher than state-of-the-art pure gold contact. Bouncing behavior was also observed in each switching cycle. The failing mechanism was also studied in relation to the contact surface changes. It was observed that the contact surfaces undergo a transfer process over the switching life time, ultimately leading to switching failure the number of bounces is also related to the fine transfer failure mechanism.