3ω

3ω Measurement / 3ω Setup

The 3ω-method allows the measurement of the thermal conductivity of bulk material and thin films. This measurement technique requires a micro heater on top of the sample which can be defined by means of lithography and subsequent metallization. Fig. 1 shows a micro heater set-up on top of a thin film. The micro heater is periodically heated by an AC current which leads to a temperature oscillation. The temperature change of the micro heater leads to a resistance change of the micro heater that creates higher harmonic voltage signals. Those higher harmonics are detected with state-of-the art lock in amplifiers. In particular the voltage signal of the threefold frequency of the input signal is used to determine thermal diffusivity and thermal conductivity. Recent literature shows that anisotropic thermal conductivity can be measured by a modified heater arrangement and detection of the second harmonic of the voltage signal [1].

We will provide the sample environment for 2ω and 3ω methods in the temperature range from 10 K to 500 K (800 K will be available in future). To exclude parasitic heat we host an evacuable closed cycle refrigerator with versatile options for thermal shielding. For best signal quality 24 coaxial wires are placed inside the cryostat and attached to the sample which is mounted inside a standard dual inline package. We can provide those packages, so that users can perform the sample preparation in the home institute.

The system will be available in summer 2018.

[1] A. T. Ramu and J. E. Bowers, A “2-omega” technique for measuring anisotropy of thermal conductivity, Rev. Sci. Instrum 83, 124903 (2012).