Fitting thermal conductivity and optimizing thermoelectric efficiency in SicGe1−c nanowires

We consider a thermoelectric energy generator constituted by a Si/Ge nanowire of length L. The dependence on composition and temperature of its thermal conductivity is analyzed in view of three series of experimental data obtained at the constant temperatures T = 300K, T = 400K, and T = 500K. The best-fit curve is determined by a nonlinear regression method (NLRM). Then, under the hypothesis of nonlinear constitutive equation for the heat flux, we investigate the thermoelectric efficiency of the system as function of the composition of the nanowire and of the difference of temperature applied to its ends. For each temperature we calculate the value of the composition which realizes the optimal efficiency of the thermoelectric energy conversion. The corresponding value of the thermal conductivity is determined as well.