Thermoelectric properties of SiO 2 /SiO 2 +CoSb multi-nanolayered thin films modified by MeV Si ions

Abstract

We have fabricated the thermoelectric generator devices from 100 alternating layers of SiO₂/SiO₂+CoSb superlattice thin films using the ion beam–assisted deposition. Rutherford backscattering spectrometry was used for quantitative elemental analysis of Si, Co, and Sb in the multilayer films. The thin films were then modified by 5-MeV Si ion bombardments using the Alabama A&M University Pelletron ion beam accelerator. Quantum dots and/or clusters were produced in the nanolayered superlattice films to decrease the cross-plane thermal conductivity, increase the cross-plane Seebeck coefficient, and the cross-plane electrical conductivity. We have characterized the thermoelectric generator devices before and after Si ion bombardments using the thermoelectric, optical, and surface characterization techniques. The optical absorption amplitude decreased when the first fluence of 1 × 10¹² ions/cm² was introduced from the value of 2.8 to about 1.9 at 200 nm. The figure of merit reached the maximum value of about 0.005 at the fluence of 1 × 10¹³ ions/cm².