Seebeck Coefficient Effects of Nanoscale Conductors in a Gaseous Flow Environment

Abstract

ABSTRACTThe surrounding ambient introduces a gaseous boundary to many potential nanotechnology applications such as nanoscale thermoelectric devices and low dimensional thermal control devices. Despite the large surface area to volume ratio of nanostructures, a formal study of the surface scattering effects induced by a gaseous boundary has received little attention. In this work, we consider the perturbing effects to the electron cloud or jellium of conducting nanostructures when submitted to a gaseous interface of varying interaction energies. Specifically, we incorporate the novel experimental method of Dynamic Electron Scattering (DES) to measure the Seebeck coefficient of 30 nm thick Au and Cu metal films in He and Ar atmospheres. The gas particle impact energy is varied by changing the flow speed from stationary (non-moving gas field) to high speed flow over the metal films. The scattering effects of each gas are clearly observable through a Seebeck coefficient increase as the gas impact energy increases. We find the high collision density of He to induce a greater increase in thermopower than the much heavier Ar with lower collision density. The perturbed transport properties of the Au and Cu thin films are explained by kinetic surface scattering mechanisms that dominate the scattering landscape of high surface area to volume ratio materials as suggested by comparative measurements on bulk Cu.