Development of Experimental Techniques for Thermoelectric Properties Characterization of Low-Dimensional Structures

This work reports current efforts in developing experimental techniques applicable for thermoelectric properties characterization at micro and nanoscale. A one-dimensional transport model was used to asses the effects of heat leakage, non-symmetric boundary conditions, and electrical contact resistance, on thermoelectric properties measurements performed by transient Harman method. If the above effects are important, the thermoelectric figure of merit cannot be extracted directly from the ratio between the Seebeck voltage and the resistive voltage drop across the sample. On the other hand, measurements of both thermal conductivity and Seebeck coefficient can be performed if the temperature drop across the sample is acquired simultaneously with the voltage drop. The theoretical model and the experimental technique are validated by measurements performed on bulk calibration samples. Furthermore, this work shows that the spatial resolution of thermoelectric properties characterization methods can be enhanced by using scanning probe based techniques. Preliminary results are presented for Seebeck coefficient measurements of p-type or n-type calibration samples performed using an AFM probe instrumented with a temperature sensor.