Dielectric charging phenomena in diamond films used in RF MEMS capacitive switches: The effect of film thickness

Abstract

The present paper aims to provide a better insight to the dielectric charging phenomena of nano-crystalline diamond (NCD) films that are used in RF MEMS capacitive switches. The electrical properties of NCD films of various thicknesses are investigated with the aid of metal-insulator-metal (MIM) capacitors. The dominant conduction mechanisms have been identified by obtaining current-voltage characteristics in the temperature range from 300 K to 400 K and dielectric charging phenomena have been investigated by using thermally stimulated depolarization currents (TSDC) technique. The experimental results indicate a thermally activated conductivity for low electric field intensities while Hill-type conduction takes place for field intensities > 130 kV/cm. The conductivity as well as the defect density seems to increase with film thickness. Enhanced dielectric charging phenomena have been observed on thicker films and the injected charges are found to be trapped through the material's volume. These results indicate that thinner NCD films seem to be more promising for RF MEMS capacitive switches. © 2016 Elsevier Lt