• Etzelstorfer, T.
• Cecchi, S.
• Stangl, J.
• Müller, E.
• Frigerio, J.
• Paul, D. J.
• Chrastina, D.
• Hague, James
• Ferrellin, L.
• Samarelli, A.
• Isella, G.

Abstract

Thermoelectrics are presently used in a number of applications for both turning heat into electricity and also for using electricity to produce cooling. Mature Si/SiGe and Ge/SiGe heteroepitaxial growth technology would allow highly efficient thermoelectric materials to be engineered, which would be compatible and integrable with complementary metal oxide silicon micropower circuits used in autonomous systems. A high thermoelectric figure of merit requires that electrical conductivity be maintained while thermal conductivity is reduced; thermoelectric figures of merit can be improved with respect to bulk thermoelectric materials by fabricating low-dimensional structures which enhance the density of states near the Fermi level and through phonon scattering at heterointerfaces. We have grown and characterized Ge-rich Ge/SiGe/Si superlattices for nanofabricated thermoelectric generators. Low-energy plasma-enhanced chemical vapor deposition has been used to obtain nanoscale-heterostructured material which is several microns thick. Crystal quality and strain control have been investigated by means of high resolution X-ray diffraction. High-resolution transmission electron microscopy images confirm the material and interface quality. Electrical conductivity has been characterized by the mobility spectrum technique.

Topics

• density
• impedance spectroscopy
• mobility
• x-ray diffraction
• transmission electron microscopy
• Silicon
• thermal conductivity
• electrical conductivity
• chemical vapor deposition