Elastic modulus study of gold thin film for use as an actuated membrane in a superconducting RF MEM switch

In earlier work a capacitively shunted superconducting MicroElectroMechanical (MEM) switch was designed and fabricated. The switch is composed of a superconducting YBa₂Cu₃O₇ coplanar waveguide structure with a Au bridge membrane suspended above an area of the center conductor covered with BaTiO₃ dielectric. The Au membrane is actuated by the electrostatic attractive force acting between transmission line and the membrane when voltage is applied. The value of the actuation force will greatly depend on the geometry and mechanical properties of the bridge material. Since Young's modulus characterizes the elastic properties of a material which is temperature dependent, it is important to find the effect of low temperature especially below the transition temperature of the superconductor in order to better understand the switch operation. Our results show that the elastic modulus for Au thin film at cryogenic temperature is 470 times bigger than it is at room temperature.