6 Watt Segmented Power Generator Modules using Bi 2 Te 3 and (InGaAs) 1-x (InAlAs) x Elements Embedded with ErAs Nanopar
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1129-V08-04
6 Watt Segmented Power Generator Modules using Bi2Te3 and (InGaAs)1-x(InAlAs)x Elements Embedded with ErAs Nanoparticles. Gehong Zeng1, Je-Hyeong Bahk1, Ashok T. Ramu1, John E. Bowers1, Hong Lu2, Arthur C. Gossard2 Zhixi Bian3, Mona Zebarjadi3 and Ali Shakouri3 1
Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, U.S.A. 2 Materials Department, University of California, Santa Barbara, CA 93106, U.S.A. 3 Electrical Engineering Department, University of California, Santa Cruz, CA 95064, U.S.A. ABSTRACT We report the fabrication and characterization of segmented element power generator modules of 16 x 16 thermoelectric elements consisting of 0.8 mm thick Bi2Te3 and 50 μm thick ErAs:(InGaAs)1-x(InAlAs)x with 0.6% ErAs by volume. Erbium Arsenide metallic nanoparticles are incorporated to create scattering centers for middle and long wavelength phonons, and to form local potential barriers for electron filtering. The thermoelectric properties of ErAs:(InGaAs)1-x(InAlAs)x were characterized in terms of electrical conductivity and Seebeck coefficient from 300 K up to 830 K. Generator modules of Bi2Te3 and ErAs:(InGaAs)1-x(InAlAs)x segmented elements were fabricated and an output power of 6.3 W was measured. 3D finite modeling shows that the performance of thermoelectric generator modules can further be enhanced by the improvement of the thermoelectric properties of the element materials, and reducing the electrical and thermal parasitic losses. INTRODUCTION Solid state thermoelectric generator modules composed of n and p semiconductor element couples can be used for directly thermal to electrical energy conversion. Their great potential in providing cleaner form of energy and reducing environmental contamination has been recognized. The power conversion performance of a thermoelectric generator module depends on the semiconductor’s thermoelectric properties, in terms of the figure of merit, Z = α2⋅σ/κ, where α is the Seebeck coefficient, σ is the electrical conductivity and κ is the thermal conductivity. Thermal conductivity can be reduced due to the increase of phonon scattering by abundant surfaces and interfaces in nanostructured materials, and the Seebeck coefficient can be increased through thermionic emission across heterointerfaces,[1] and/or electron scattering by nanostructures.[2, 3] Thermal conductivity reduction using superlattice heterostructures or incorporation of nanoparticles has been demonstrated [4, 5]. When ErAs nanoparticles are incorporated into (InGaAs)1-x(InAlAs)x, potential barriers are formed at the interface between the particle and semiconductor. The Seebeck coefficient can therefore be enhanced through the electron filtering effects of these potential barriers.[6] The performance of a solid state generator also depends on the Carnot efficiency, which can be expressed as ΔT/Th., where ΔT is the temperature difference across the elements, and Th the hot side temperature of the elements. Large ΔT is desirable for large output power and
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