Thermoelectric Properties of Epitaxial PbSe- and PbSrSe-Thin Films

Epitaxial Films of PbSe and PbSrSe are grown by MBE on BaF2(111)-substrates. Carrier concentrations between 10 18 and 10 19 cm-3 are studies. For the PbSrSe films different Sr concentrations below 10at% Sr were used resulting in films of energy-gaps between 0.3 and 0.6 eV. The properties of the films were investigated by IR-transmission spectroscopy, Hall effect, measurement of the conductivity sigma, and of the Seebeck-coefficient alfa. Electron channeling patterns and X-ray-diffraction showed good epitaxial quality of the films. From the elcectrical data power factors alfa²sigma are obtained at 300 K and as a function of temperature for a series of samples. The 300 K data come close to results of T.C. Harman et al. [1] for PbTe films as function of carrier concentration. Data obtain from a recent measurement of the thermal conductivity of a recent measurement of the thermal conductivity of a PbSe-film can be used to calculate the thermoelectric efficiency Z. A comparison of these dat a with the values reported in[1] indicates that for thermoelectric applications at room temperature PbSe has approximately the same efficiency as PbTe.