Abstract
The influence of oxygen vacancies on the transport properties of epitaxial thermoelectric (Sr, La)TiO3 thin films is determined using electrical and spectroscopic ellipsometry (SE) measurements. Oxygen vacancy concentration was varied by ex-situ annealing in Ar and Ar/H-2. All films exhibited degenerate semiconducting behavior, and electrical conductivity decreased (258-133 S cm(-1)) with increasing oxygen content. Similar decrease in the Seebeck coefficient is observed and attributed to a decrease in effective mass (7.8-3.2m(e)), as determined by SE. Excellent agreement between transport properties deduced from SE and direct electrical measurements suggests that SE is an effective tool for studying oxide thin film thermoelectrics. (C) 2012 American Institute of Physics. [doi:10.1063/1.3678186]