MeV Si ions bombardment effects on thermoelectric properties of sequentially deposited SiO2/AuxSiO2(1−x) nano-layers

Abstract

We prepared 50 periodic nano-layers of electro-cooling system consisting of SiO2/AuxSiO2(1−x) super lattice with Au layer deposited on both sides as metal contacts. The deposited multilayer films have a periodic structure consisting of alternating layers where each layer is 10nm thick. The purpose of this research is to tailor the figure of merit of layered structures used as thermoelectric generators. The super lattices were then bombarded by 5MeV Si ions at three different fluences to form nano-cluster structure. Rutherford backscattering spectrometry (RBS) was used to monitor the film thickness and stoichiometry before and after MeV bombardment. We measured the thermoelectric efficiency of the fabricated device before and after 5MeV bombardment measuring the cross plane thermal conductivity by third harmonic method, measuring cross plane Seebeck coefficient, and measuring electric conductivity using Van der Pauw method. As predicted the electronic energy deposited due to ionization by MeV Si beam in its track produces nano-scale structures which disrupt and confine phonon transmission therefore reducing thermal conductivity, increasing electron density of state so as to increase Seebeck coefficient, and electric conductivity, thus increasing figure of merit.