Thin-film aerogel thermal conductivity measurements via 3ω

Abstract

The limiting constraint in a growing number of nano systems is the inability to thermally tune devices. Silica aerogel is widely accepted as the best solid thermal insulator in existence and offers a promising solution for microelectronic systems needing superior thermal isolation. In this study, thin-film silica aerogel films varying in thickness from 250 to 1280nm were deposited on SiO2 substrates under a variety of deposition conditions. These samples were then thermally characterized using the 3ω technique. Deposition processes for depositing the 3ω testing mask to the sample were optimized and it was demonstrated that thin-film aerogel can maintain its structure in common fabrication processes for microelectromechanical systems. Results indicate that thin-film silica aerogel can maintain the unique, ultra-low thermal conductivity commonly observed in bulk aerogel, with a directly measured thermal conductivity as low as 0.024W/m-K at temperature of 295K and pressure between 0.1 and 1Pa.