Thermoelectrics: Direct Thermal to Electrical Energy Conversion

Thermoelectric materials convert thermal temperature gradient directly into electrical energy, and have enormous potential in dealing with the present day energy challenge. Since about 40% of the total energy spent in most devices is wasted as heat, thermoelectricity provides an effective way to recover some of these wasted energies, and convert them into electrical power. The efficiency of thermoelectric materials are represented by its dimention less figure of merit ZT, must exhibit a high value of about 3-4 at operating temperatures for it to be competitive with conventional technologies.

Our approach is to use nitride semiconductors and metal/semiconductor superlattices to improve the efficiency of the thermoelectric materials. The Schottky barrier at the metal/semiconductor interface should result in energy filtering of electrons that would increase the Seebeck coefficient of the material without reducing the electrical conductivity. While the interfaces in the superlattice would also acts as a barrier for the phonon transport reducing the thermal conductivity.

Publication

1. P. V. Burmistrova, J. Maassen, T. Favaloro, B. Saha, S. Salamat, Y. R. Koh, M. S. Lundstrom, A. Shakouri, and T. D. Sands, "High mobility and high thermoelectric power factor in epitaxial ScN films deposited by reactive magnetron sputtering onto MgO(001) substrate." J. Appl. Phys. 113, 153704 (2013).

2. B. Saha, T. D. Sands and U. V. Waghmare, "Electronic structure, vibrational spectra and thermal properties of HfN/ScN metal/semiconductor superlattices: A first-principles Study." J. Phys.: Cond. Matt., 24 415303, (2012).

3. B. Saha, T. D. Sands and U. V. Waghmare, "First-principles analysis of thermoelectric ZrN/ScN metal/semiconductor superlattices", J. Appl. Phys. 109, 073720 (2011).