MeV Si Ions Bombardment Effects on SiO2/SiO2-ZrNiSn Nano-layered Thermoelectric Generator
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1102-LL04-27
MeV Si Ions Bombardment Effects on SiO2/SiO2-ZrNiSn nano-layered Thermoelectric Generator S. Budak1, S. Guner2,3, C. Muntele2, and D. ILA2 1 Electrical Engineering, Alabama A&M University, 4900 Meridian Street, Normal, AL, 35762 2 Center for Irradiation of Materials, Alabama A&M University, 4900 Meridian Street, Normal, AL, 35762 3 Department of Physics, Fatih University, B.Cekmece, Istanbul, 34500, Turkey Abstract We have deposited 50 nano-layers of 710 nm of SiO2/SiO2+ZrNiSn with a periodic structure consisting of alternating layers where each layer is about 14 nm thick. The purpose of this research is to generate nanolayers of nanostructures of ZrNiSn with SiO2 as host and as buffer layer using a combination of co-deposition and MeV ion bombardment taking advantage of the energy deposited in the MeV ions track to nucleate nanostructures. The performance of the thermoelectric materials and devices is shown by a dimensionless figure of merit, ZT = S 2σT / κ , where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature and κ is the thermal conductivity. ZT can be increased by increasing S, increasing σ, or decreasing κ. The electrical and thermal properties of the layered structures were studied before and after bombardment by 5 MeV Si ions at seven different fluences ranging from 1014 to 1015 ions/cm2 in order to form nanostructures in layers of SiO2 containing few percent of ZrNiSn. Rutherford Backscattering Spectrometry (RBS) was used to monitor elemental analysis of the film. Keywords: Ion bombardment, thermoelectric properties, multi-nanolayers, SiO2/SiO2+ZrNiSn, Rutherford backscattering, 3 omega method thermal conductivity measurement, Seebeck coefficient, Figure of merit *Corresponding author: S. Budak; Tel.: 256-372-5894; Fax: 256-372-5855; Email: [email protected] 1. INTRODUCTION Thermoelectric materials are increasingly important due to their applications in thermoelectric power generation and microelectronic cooling [1]. Effective thermoelectric materials have a low thermal conductivity and a high electrical conductivity [2]. The ZrNiSn half-Heusler alloy is one of the potential candidates for the thermoelectric materials and has recently received great interest [3]. The performance of the thermoelectric materials and devices is described by a dimensionless Figure of Merit, ZT = S 2σT / κ , where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity [4]. Higher ZT can be reached by increasing S, increasing σ, or decreasing κ. Understanding the thermal conductivity and heat transfer processes in thin films and superlattice structures is critical for the development of microelectronic and optoelectronic devices. Experimental results on the thermal conductivity of superlattices for several materials demonstrate that the thermal
conductivity of a superlattice could be much lower than that the estimated from the bulk values of its constituent materials, and even smaller than the
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