Modeling of Enhanced Thermoelectric Processes Based on Asymmetrically-Graded Superlattices
Abstract
In this study, we explore the influence of spatially graded energy bands on the thermoelectric properties of thin film semiconductors. In the analysis, we utilize the semi-classical Boltzmann equation in the relaxation approximation. The thermoelectric variables are calculated in terms of spatially varying, band engineered conduction and valence band edges, and a spatially dependent electron-phonon relaxation time based on longitudinal acoustic dispersion; use is made of the spherical band approximation and a spatially dependent effective mass for conduction and valence hand carriers to obtain explicit parametric results for the Seebeck coefficient and the figure of merit for a model slab of material of finite length. The Seebeck coefficient is determined and is shown to be enhanced by the addition of a term which depends analytically upon a spatial average of the relative "band engineered" energy hand edge divided by k T(x), where T(x) is the spatially dependent temperature across the sample. The figure of merit, Z T, is also estimated in terms of band engineered variables and discussed in the light of a variational principle which allows for the optimization of Z T. Suggestions for more detailed and rigorous analysis of thermoelectric transport and optimization of Z T are discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 12, 2005
- Accession Number
- ADA429401
Entities
People
- Gerald J. Iafrate
Organizations
- North Carolina State University