Dimitrios, "Strain rate sensitivity of nanocrystalline Au films at room temperature" (2010) AbstractThe effect of strain rate on the inelastic properties of nanocrystalline Au films was quantified with 0.85 and 1.76 lm free-standing microscale tension specimens tested over eight decades of strain rate, between 6 Â 10 À6 and 20 s À1 . The elastic modulus was independent of the strain rate, 66 ± 4.5 GPa, but the inelastic mechanical response was clearly rate sensitive. The yield strength and the ultimate tensile strength increased with the strain rate in the ranges 575-895 MPa and 675-940 MPa, respectively, with the yield strength reaching the tensile strength at strain rates faster than 10 À1 s À1 . The activation volumes for the two film thicknesses were 4.5 and 8.1 b 3 , at strain rates smaller than 10 À4 s À1 and 12.5 and 14.6 b 3 at strain rates higher than 10 À4 s À1 , while the strain rate sensitivity factor and the ultimate tensile strain increased below 10 À4 s À1 . The latter trends indicated that the strain rate regime 10 À5 -10 À4 s À1 is pivotal in the mechanical response of the particular nanocrystalline Au films. The increased rate sensitivity and the reduced activation volume at slow strain rates were attributed to grain boundary processes that also led to prolonged (5-6 h) and significant primary creep with initial strain rate of the order of 10 À7 s À1 .

Abstract-This paper reports on the growth, patterning, and characterization of plasma-enhanced chemical vapor deposition (PECVD) thin diamond film for DC-65 GHz applications. Nanocrystalline films are successfully demonstrated with an average grain size of less than 60 nm that can replace conventional low-quality dielectrics in RF MEMS switches. In addition to their excellent surface properties, the diamond film has negligible RF loss up to at least 65 GHz, but non-zero DC conductivity of approximately 0.2 µS/m that allows the film to provide a conductive path for potential trapped charges. Such films are envisioned to be integrated in today's capacitive RF MEMS switches that suffer from charge-induced stiction.

No abstract