Thermionic Energy Conversion
Thermionic Energy Conversion
ONR Multi University Research Initiative (MURI)
Thermionic Energy Conversion Center
UCSC, Berkeley, Harvard, MIT, Purdue, NCSU, UCSB
Program Manager: Mihal Gross, ONR
A. Shakouri et al., "Solid-State and Vacuum Thermionic Energy Conversion," Invited Talk, Material Society Fall Meeting, December, 2005; Boston, MA
Ali Shakouri, "Thermoelectric, thermionic and thermophotovoltaic energy conversion", Invited Talk; Proceedings of International Conference on Thermoelectronics , pp. 492-497, Clemson SC , June 2005.
Direct thermal to electrical energy conversion systems that could operate at lower temperatures (300-650C) with high efficiencies (>15-20%) provide an attractive compact alternative to internal combustion engines for many applications in the W-MW range. They will also expand the possibilities for waste heat recovery applications. Thermionic Energy Conversion Center’s goal is to design, fabricate and characterize direct energy conversion systems that meet the above requirements. The core of the solution we are investigating is an integrated approach to engineer electrical, thermal and optical properties of nanostructured materials and devices in order to fabricate more efficient solid-state and vacuum-based thermionic energy conversion components and systems. A unique team of researchers experienced in materials, physics, electrical and mechanical engineering has been assembled to address fundamental limits to existing systems.
Materials design is focused on increasing the efficiency of heterostructure thermionic power generators using embedded quantum dot structures and metal/semiconductor superlattices and the development of thermionic energy conversion based on thermionic-field emission from nanostructured carbon surfaces and low work function n-type wide band gap semiconductor collectors. Measurements of electrical, optical and thermal transport at both the device and nanostructure level will be used to verify model predictions and thereby lay the foundation for improved device and materials design. Finally, various components will be integrated and packaged for systems demonstration.
In summary, we are investigating new approaches for direct thermal to electric energy conversion which have distinct advantages over the present state of the art: 1) improved thermoelectric/thermionic figure-of-merit, 2) lower temperature and highly efficient thermionic vacuum emitter-collector systems 3) integrated optimization of electrical, thermal and optical properties, 4) use of integrated circuit fabrication techniques for a scalable solution in the W-MW energy range 5) light weight and silent thin film devices. We are concentrating on fundamental research into new, innovative ways of thermal to electric energy conversion, which will result in practical new integrated components with greatly improved performance and reliability. This research can be directly applied to other areas of waste heat recovery at different temperature ranges.
TEC Center Director
Griff Bilbro (NCSU): Ph.D. University of Illinois at Urbana 1977
Professor of Electrical and Computer Engineering
Expertise: Analog, rf and mixed mode including Microwave Devices and Circuits, nanoelectronics and photonics
John E. Bowers (UCSB): Ph.D. Stanford 1980
Professor Electrical and Computer Engineering; Fellow APS and IEEE, PYI-NSF, Streifer Award 1986
Expertise: optoelectronics, high speed photonics and electronics, thin film TE/TI
Robert Davis (NCSU): Ph.D. Berkeley 1970
Kobe Steel Ltd. Distinguished University Professor
Expertise: Growth and characterization of semiconductors, ceramic thin films and ceramic coatings, kinetics and mechanisms of creep in ceramic materials.
Art Gossard (UCSB): Ph.D. Berkeley 1960
Professor Material Science; member NAS, NAE; Fellow APS and IEEE, Buckley Prize, McGroddy Prize
Expertise: molecular beam epitaxy, artificially structured materials for optoelectronic.
Arun Majumdar (Berkeley): TEC Center Associate Director, Ph.D. Berkeley 1989
Professor Mechanical Engineering, Larson Memorial Award 2001
Expertise: Nanoscale Diagnostics; Energy Conversion and Transport in Nanostructures; Optomechanical Microdevices.
Venky Narayanamurti (Harvard): Ph.D. Cornell 1965
Dean of Engineering, Armstrong Professor of Engineering and Applied Sciences and Professor of Physics; member NAE; Fellow IEEE.
Expertise: electron and phonon transport in semiconductor heterostructures, phonon spectroscopy; Ballistic Electron Emission Microscopy
Bob Nemanich (NCSU): TEC Center Associate Director, Ph.D., Chicago 1976
Professor, Physics; Material Research Society President '98, Fellow APS
Expertise: electronic materials, surface physics.
Rajeev J. Ram (MIT): Ph.D., UCSB 1997
Associate Professor, Electrical Engineering; ITT Chair 2001, ONR Young Investigator 1999, NSF CAREER 1998
Expertise: Directs Physical Optics and Electronics Group at MIT. Research focus on optoelectronics., AFM/STM, quantum optics, thermoelectric effects in bipolar devices.
Tim Sands (Purdue): Ph.D. Berkeley 1984
Basil S. Turner Professor of Engineering
Expertise: heterogeneous materials integration, laser processing of materials, thermoelectric materials, metal/semiconductor interfaces and heterostructures.
Holger Schmidt (UCSC): Ph.D., UCSB 1999
Associate Professor, Electrical Engineering, NSF CAREER 2002
Expertise: Fourier spectroscopy, ultrafast spectroscopy, optical quantum interference, quantum optics.
Zlatko Sitar (NCSU): Ph.D. NCSU 1990
Professor Materials Science and Engineering
Expertise: Thin film and bulk crystal growth of wide bandgap III-nitride semiconductors; heteroepitaxial growth of diamond thin films; silicon on diamond technology; field emission from carbon materials.
Susanne Stemmer (UCSB): Ph.D. Stuttgart 1995
Professor Material Science;
Expertise: Novel transmission electron microscopy imaging and spectroscopy techniques, such as Z-contrast imaging and atomic resolution EELS.
Ali Shakouri (UCSC): TEC Center Director, Ph.D. Caltech 1995
Professor of Electrical Engineering. Packard Fellowship 1999, NSF CAREER 2000
Expertise: Thin films and superlattice thermoelectrics/thermionics, microrefrigerators on a chip, electron transport in quantum heterostructures, photonic integrated circuits, thermoreflectance imaging.
- J. M. O. Zide, D. Vashaee, G. Zeng, J. E. Bowers, A. Shakouri, A. C. Gossard, "Demonstration of electron filtering to increase the Seebeck coefficient in ErAs:InGaAs/InGaAlAs superlattices," Physical Review B, April 2006.
- G. Zeng, J. E. Bowers, J. M. O. Zide, A. C. Gossard, W. Kim, S. Singer, A. Majumdar, R. Singh, Z. Bian, Y. Zhang, and A. Shakouri, "ErAs:InGaAs/InGaAlAs superlattice thin-film power generator array", Applied Physics Letters 88, 113502-1-3, March, 2006
- Kim, W., Zide, J., Gossard, A., Klenov, D., Stemmer, S., Shakouri, A., and Majumdar, A., "Thermal conductivity reduction and thermoelectric figure of merit increase by embedding nanoparticles in crystalline semiconductors," Phys. Rev. Lett. 96, 045901 (2006).
- Kim, W., Singer, S., Majumdar, A., Vashaee, D., Zhixi, B., Shakouri, A., Zeng, G., Bowers, J. E., Zide, J. M. O., and Gossard, A. C., "Cross-plane lattice and electronic thermal conductivities of ErAs:InGaAs/InGaAlAs superlattices," Appl. Phys. Lett., 88, 242107 (2006).
- Mona Zebarjadi, Ali Shakouri and Keivan Esfarjani, "Thermoelectric transport perpendicular to thin-film heterostructures calculated using the Monte Carlo technique",Phys. Rev. B 74, 195331 (2006)
- Zhixi Bian and Ali Shakouri, "Enhanced solid-state thermionic emission in non-planar heterostructures," Appl. Phys. Lett. 88, 012102 (2006).
- Zhixi Bian and Ali Shakouri, "Beating the maximum cooling limit with graded thermoelectric materials," Appl. Phys. Lett. 89, 212101 (2006).
- Zhixi Bian, Ali Shakouri, "Cooling enhancement using inhomogeneous thermoelectric materials," International Conference on Thermoelectronics, August 2006.
- V. Rawat and T. Sands, "Growth of TiN/GaN Metal/Semiconductor Multilayers by Reactive Pulsed Laser Deposition," JAP 2006.
- Kim, W., and Majumdar, A., "Phonon scattering cross section of polydispersed spherical nanoparticles," J. Appl. Phys. 99, 084306 (2006).
- P. Mayer, R. J. Ram, "Optimization of Heat-sink Limited Thermoelectric Generators," Nanoscale and Microscale Thermophysical Engineering , May, 2006.
- Koeck FAM, Nemanich RJ. "Emission characterization from nitrogen-doped diamond with respect to energy conversion," Diamond and Related Materials, vol.15, no.2-3, Feb.-March 2006, pp. 217-20.
- A. Aleksov, J.M. Gobien, X. Li, J.T. Prater and Z. Sitar, "Silicon-On-Diamond - an engineered substrate for electronic applications", Diamond and Related Materials, 15, 248-253 (2006)
- Koeck FAM, Nemanich RJ. "Sulfur doped nanocrystalline diamond films as field enhancement based thermionic emitters and their role in energy conversion," Diamond and Related Materials, vol.14, no.11-12, Nov. 2005, pp. 2051-4.
- A. Aleksov, X. Li, N. Govindaraju, J. M. Gobien, S. D. Wolter, J. T. Prater, Z. Sitar, "Silicon on Diamond: an advanced Silicon on Insulator technology", Diamond and Related Materials, 14, 308-313 (2005)
- K.J. Russell, Ian Appelbaum, V. Narayanmurti, M.P. Hanson, and A.C. Gossard, Transverse momentum nonconservation at the ErAs/GaAs interface, Phys. Rev. B 71, 121311(R) (2005).