Thermal conductivity measurement of suspended Si-N membranes from 10 K to 275 K using the 3ω-Völklein method

The thermal properties of suspended thin films prepared by the micro-machining process have been measured using the 3ω dynamic method coupled to a Völklein geometry. A transducer (heater/thermometer) centered on the membrane is driven by an ac current causing periodic thermal oscillations. The measurement of the temperature oscillation on the membrane is made at the third harmonic using a Wheatstone bridge set up. Here by coupling the 3ω method to a Völklein geometry (suspended membrane) we obtained a highly sensitive technique to measure the thermal conductance with a resolution of (ΔK/K = 10−3) and a sensitivity of the order of nanoWatt/K, thanks to a very sensitive niobium nitride thermometry. This method is applied to measure the in-plane thermal conductivity of 100 nm silicon nitride membrane, in the temperature range of 10–275 K