Performance of Nanoscale Quantum Well Thermoelectrics

Alternating 10 nm thermoelectric films of N-type Si/SiGe and P-type Si/SiGe and B₄C/B₉C have been fabricated on various substrates, electrically joined and thermoelectric properties measured from 40°K up to 700°K. These nanoscale thermoelectric films demonstrate excellent thermoelectric power factors significantly higher than current bulk thermoelectric materials. The implications of the measured thermoelectric Seebeck coefficient data and electrical resistivity data for alternating 10 nm films that are grown to thicknesses of one to 10 microns means efficiencies of 15% at 200°C temperature differences and efficiencies of 30% at 400°C temperature differences. Utilizing Seebeck and resistivity data obtained by Hi-Z and UCSD, along with published bulk thermal conductivity data, which is conservative, unique thermoelectric module and generator concept designs for both power generation and cooling are presented over wide temperature and power ranges.