Telluride thin films: growth, strain, structure and thermoelectric properties

Utilizing a superlattice structure is an advantage in enhancing the thermoelectric performance. For instance, the Bi2Te3/Sb2Te3 superlattice is famous for its exceptionally high figure of merit. 3D/3D films systems have been studied most intensely and have been successfully applied in industry. However, introduction of 2D materials makes the strain behaviour in hetero-structures elusive. It is well known that the electronic properties of materials can be extremely sensitive to the strain, and doping can easily affect the Seebeck coefficient of materials. However, the strain state and the thermal stability of these multilayers are still not studied in-depth, which may be the possible reasons why different researchers generated such a wide spread in (thermoelectric) data. In this thesis, we use telluride films i.e., Bi2Te3, Sb2Te3, Ge1+xTe, and GeTe, as examples to address the strain evolution in these materials and how the nanostructure and intermixing affect the thermoelectric properties.