Investigation of the thermal properties of thin solid materials at different temperature levels using a set of microresistors

•A technique for thermal characterization of solid materials is proposed.•1D analytical model is shown for the case of solid materials.•First tests were done on samples made of silicon.•Numerical simulations were done to show the domain of validity of the model.•Experimental results are in good agreement with the scientific literature values.

The measurement of thermal properties of solid materials at different temperatures above ambient is investigated using a set of microresistors. Samples consisted of suspended films with sets of long, parallel resistive wires deposited on their surfaces. One resistive wire was heated by an alternating current. Surface temperature changes in DC and AC regimes were then detected by measuring the change in electrical resistance of the other wires deposited on the surface. The length of wires was chosen so that they may be assumed isothermal and such that heat diffusion acts perpendicularly to their axes. By measuring the dependence of the surface alternating temperature oscillation on the modulation frequency f and on the separation between the heating wire and the probing wires, the thermal diffusivity of the sample was determined. Through adjustment of the alternating current amplitude in the source wire, the temperature at which the thermal diffusivity of the sample was evaluated was finely controlled. For the validation of the method, pure silicon samples were first studied. An experimental bench was set up and resistive source and probes were experimentally characterized. Results obtained from ambient temperature to 500 K for pure silicon are in accordance with reference data found in the scientific literature.