Chiang Mai Journal of Science

We report the two-dimensional (2D) anisotropic electronic structure which is originated from the polar surface of La0.1Sr0.9TiO3 (110) using angle-resolved photoemission spectroscopy (ARPES). The light and heavy electron effective masses of 0.41me and 10.39me with calculated 2D electron density up to 2x1014 cm-2 have been observed which drops in the perfect range for thermoelectric applications. The origin of an anisotropic behavior was studied by tight binding (TB) model which can be described by the anisotropic nature of Ti d-orbitals in this orientation. By semi-classical approach, the Seebeck coefficient (S) can be calculated up 170 μV/K at room temperature; this Seebeck coefficient can be enhanced at specific electron densities due to the electronic structure of the 2DEG state which is modified, comparing to the bulk state. This finding suggests the opportunity to engineer anisotropic surface and doping concentration to enhance the performance of the oxide-based thermoelectric devices.