Bi2Te3 based low dimensional structures are interesting material systems to increase the thermoelectric figure of merit ZT by either the expected reduction of the thermal conductivity or by a possible power factor enhancement due to quantum confinement. Due to low lattice mismatch Bi2(Te1-xSex)3, PbSe1-xTex, as well as Pb1-xSrxTe, and BaF2 are suitable for Bi2Te3 based low dimensional structures. Especially due to their significantly enhanced band gap lead chalcogenide compounds like Pb1-xSrxTe (Pb0.87Sr0.13Te: 0.6 eV) are well-suited barrier materials in MQW structures. Alternatively the insulator BaF2 can be used for that purpose.
Here we report mainly on results of different superlattice structures mentioned above grown by molecular beam epitaxy (MBE) on BaF2(111). The structural properties of these layers were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and secondary ion mass spectroscopy (SIMS). Structural performance and thermoelectric properties of different Bi2Te3 based superlattices were reported and compared with regard to their superlattice parameters.