New thermal method for the characterization of solid materials at different temperature levels

A new method for evaluating the thermal properties of solid materials at different temperatures is proposed. An array of parallel and long resistive lines is deposited on the surface of the sample that is shaped in a suspended film several hundred μm in thickness. One of the resistive lines of this array is heated with an alternative current. The surface temperature changes in DC and AC regimes are detected by measuring the electrical resistance change of each of the other lines of the array. The length of wires was chosen so that they may be assumed isothermal and heat diffusion operates perpendicularly to them. By measuring the dependence of the surface alternative temperature rise on the modulation frequency f and on the separation between the heating wire and the probe wires, the thermal diffusivity of sample can be determined. The adjustment of the amplitude of the alternative current in the source allows controlling the sample temperature at which the thermal diffusivity is evaluated. For the validation of the proposed method, pure silicon samples were first studied. The experimental bench was set up and resistive source and probes were experimentally characterized. Results obtained at different temperatures until 500 K for pure silicon are in good accordance with the ones obtained elsewhere in the scientific literature by modeling as well as other experimental techniques.