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1267-DD05-15

Effects of MeV Si Ions Modification on the Thermoelectric Properties of SiO2/SiO2+Cu Multilayer Thin Films

J. Chacha1, S. Budak1, C. Smith2, M. Pugh1, K. Ogbara3, K. Heidary1, R. B. Johnson 3, C. Muntele2, D.ILA2 1

Department of Electrical Engineering, Alabama A&M University, Normal, AL USA 2 Center for Irradiation of Materials, Alabama A&M University, Normal, AL USA 3 Department of Physics, Alabama A&M University, Normal, AL USA Abstract

The performance of the thermoelectric materials and devices is shown by a dimensionless figure of merit, ZT = S2σT/K, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature and K is the thermal conductivity. ZT can be increased by increasing S, increasing σ, or decreasing K. We have prepared 100 alternating multi-nano layer of SiO2/SiO2+Cu superlattice films using the ion beam assisted deposition (IBAD). The 5 MeV Si ions bombardments have been performed at the different fluences using the AAMU Pelletron ion beam accelerator to make quantum clusters in the multi-layer superlattice thin films to decrease the cross plane thermal conductivity increase the cross plane Seebeck coefficient and cross plane electrical conductivity. To characterize the thermoelectric thin films before and after Si ion bombardments we have measured the cross-plane Seebeck coefficient, the cross-plane electrical conductivity, and the cross-plane thermal conductivity for different fluences. *Corresponding author: S. Budak; Tel.: 256-372-5894; Fax: 256-372-5855; Email: [email protected] 1. INTRODUCTION The technology of thermoelectricity began during the World War II when Soviet Union, under the Academician Ioffe’s inspiration, produced 2–4 watt thermoelectric generators to be capable of powering a small radio from a small cooking fire [1]. In recent decades, as the world’s demand for exploiting new energy conversion materials increases, continuing interests have being focused on thermoelectric (TE) materials because of their clean and sustainable energy converting characteristics [2]. Thermoelectric devices are basically categorized into two groups on the direction of energy conversion: thermoelectric cooler (TEC) converting electricity to thermal energy and thermoelectric generator (TEG) converting heat into electricity. The thermoelectric cooler is a device in which an electric current is applied to semiconductor devices to produce an appreciable temperature difference at the two ends of the semiconductor [3]. The efficiency of the thermoelectric devices and materials is determined by the figure of merit ZT [4]. The figure of merit is defined by 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 [5, 6]. ZT can be increased by increasing S, by increasing σ, or by decreasing κ. Thermoelectric generators constitute two materials of n and p type bulk materials. Since we are working with the superlattice thin film systems, the superlattice thin