Abstract
The design and fabrication of nanostructured materials to control both thermal and electrical properties are demonstrated for high-performance thermoelectric conversion. We have focused on silicon (Si) because it is an environmentally friendly and ubiquitous element. High bulk thermal conductivity of Si limits its potential as a thermoelectric material. The thermal conductivity of Si has been reduced by introducing grains, or wires, yet a further reduction is required while retaining a high electrical conductivity. We have designed two different nanostructures for this purpose. One structure is connected Si nanodots (NDs) with the same crystal orientation. The phonons scattering at the interfaces of these NDs occurred and it depended on the ND size. As a result of phonon scattering, the thermal conductivity of this nanostructured material was below/close to the amorphous limit. The other structure is Si films containing epitaxially grown Ge NDs. The Si layer imparted high electrical conductivity, while the Ge NDs served as phonon scattering bodies reducing thermal conductivity drastically. This work gives a methodology for the independent control of electron and phonon transport using nanostructured materials. This can bring the realization of thermoelectric Si-based materials that are compatible with large scale integrated circuit processing technologies.
Highlights
The nanostructure science has received significant attention because nanostructured materials can exhibit novel characteristics that the bulk materials do not show
We have proposed the guideline for the independent control of heat flow and electric current by introducing well-controlled, nanostructured interfaces
Using an ultrathin Si oxide film technique, structures that consisted of connected epitaxial Si NDs or Si films containing epitaxial Ge NDs were formed
Summary
The nanostructure science has received significant attention because nanostructured materials can exhibit novel characteristics that the bulk materials do not show. Thermoelectric conversion is an important item for thermal management (Figure 1) and offers the possibility for waste heat to be reused as electrical energy. This can be an ideal energy source. The thermal physics of phonon transport in nanostructured materials must be understood to allow for independent control of electrical and thermal transport, which will lead to non-conventional thermoelectric materials with high efficiency. We outline a methodology for the independent control of phonon and electron transport in the materials that have a large phonon contribution to heat transport This is achieved using nanostructure formation technologies (Figure 1). Strategy for thermal and electrical control using nanostructure design and formation technologies
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
