Internal Friction and Young's Modulus Measurements on SiO2 and Ta2O5 Films Done with an Ultra-High Q Silicon-Wafer Suspension

Abstract

In order to study the internal friction of thin films a nodal suspension system called GeNS (Gentle Nodal Suspension) has been developed. The key features of this system are: i) the possibility to use substrates easily available like silicon wafers; ii) extremely low excess losses coming from the suspension system which allows to measure Q factors in excess of 2×108 on 3” diameter wafers; iii) reproducibility of measurements within few percent on mechanical losses and 0.01% on resonant frequencies; iv) absence of clamping; v) the capability to operate at cryogenic temperatures. Measurements at cryogenic temperatures on SiO2 and at room temperature only on Ta2O5 films deposited on silicon are presented.

Keywords

• Ultra low loss suspensions
• Q measurements
• optical dielectric coatings
• silica
• tantala Ta2O5
• thin films