LAUSR

Measurements of thermoelectric effects such as the Seebeck effect, the generation of electric field in response to an applied thermal gradient, are important for a range of thin films and nanostructures used in nanoscale devices subject to heating. In many cases, a clear understanding of the fundamental physics of these devices requires knowledge of the intrinsic thermoelectric properties of the material, rather than the so-called “relative” quantity that comes directly from measurements and always includes contributions from the voltage leads. However, for a thin film or nanostructure, determining the absolute Seebeck coefficient, α abs, is challenging. Here, we first overview the challenges for measuring α abs and then present an approach for determining α abs for thin films from relative measurements made with a micromachined thermal isolation platform at temperatures between 77 and 350 K. This relies on a relatively simple theoretical description based on the Mott relation for a thin film sample as a function of thickness. We demonstrate this technique for a range of metal thin films, which show that α abs almost never matches expectations from tabulated bulk values, and that for some metals (most notably gold) even the sign of α abs can be reversed. We also comment on the role of phonon and magnon drag for some metal films.Measurements of thermoelectric effects such as the Seebeck effect, the generation of electric field in response to an applied thermal gradient, are important for a range of thin films and nanostructures used in nanoscale devices subject to heating. In many cases, a clear understanding of the fundamental physics of these devices requires knowledge of the intrinsic thermoelectric properties of the material, rather than the so-called “relative” quantity that comes directly from measurements and always includes contributions from the voltage leads. However, for a thin film or nanostructure, determining the absolute Seebeck coefficient, α abs, is challenging. Here, we first overview the challenges for measuring α abs and then present an approach for determining α abs for thin films from relative measurements made with a micromachined thermal isolation platform at temperatures between 77 and 350 K. This relies on a relatively simple theoretical description based on the Mott relation for a t...