(Invited) Solution-Processing Routes to Conductive Ultrathin Films of Ruthenium Dioxide...on Any Substrate

The deposition of continuous, ultrathin, conductive films from liquid-phase is still a rare processing outcome. We have demonstrated that RuO₂ can be deposited from chilled, nonaqueous solutions of RuO₄ as an ~10 nm–thick film on planar substrates using a scalable, atom-efficient, self-limiting synthetic protocol [1]. The versatility of this protocol is exemplified in that deposition ensues on any type of substrate—metal, semiconductor, ceramic, polymer, or salt—or whether the substrate is planar, curved, or non-line-of-sight [1–3]. The resulting air- and water-stable conductive oxide, even though nanoscopic, is electrically conductive and broadband transparent over an uncommonly wide range for an oxide—from UV to microwave—far surpassing the spectral window of indium-doped tin oxide (ITO) [1]. Recently, we were able to isolate square centimeters of self-supporting, ultrathin RuO₂ films, by releasing them from soluble substrates. The freestanding films are also conductive and transparent, exhibiting unexpected mechanical flexibility and strength. They can then be manipulated and further characterized by being placed on holders (i.e., TEM grids) or devices (i.e. nanofabricated stages for mechanical or thermal transport measurements). We will provide an overview of the synthetic methods and the characterization of this ultrathin, disordered material, including optical, structural, thermal and mechanical properties.

[1]   D.R. Rolison, J.W. Long, C.N. Chervin, J.C. Lytle, and K.A. Pettigrew, U.S. Patent #8,889,257; J.W. Long, J.C. Owrutsky, C.N. Chervin, D.R. Rolison, J.S. Melinger, U.S. Patent, issued 9-Dec-2014.

[2]   C.N. Chervin, A.M. Lubers, K.A. Pettigrew, J.W. Long, M.A. Westgate, J.J. Fontanella, D.R. Rolison, Nano Lett. 9 (2009) 2316–2321.

[3]  C.P. Rhodes, J.W. Long, K.A. Pettigrew, R.M. Stroud, and D.R. Rolison, Nanoscale 3 (2011) 1731–1740.