ABSTRACT
The U.S. Department of Defense (DoD) has been supporting the resurgence of the once sleepy field of
thermoelectrics during the past decade, since the first set of ideas using nanoscale materials
were
proposed at the National Thermogenic Workshop in 1992. In particular, the Office of Naval Research
(ONR) and the Defense Advanced Research Projects Agency (DARPA) have helped make impressive
strides in the materials figure-of-merit, denoted as ZT, using nanoscale material concepts. Higher ZT of
the thermoelectric materials can directly lead to improved efficiencies in both solid-state refrigeration
and thermal-to-electric power conversion devices. There have been several reports
of enhanced ZT
at various temperature regimes using superlattices, quantum dots, and nanocrystalline inclusions,
respectively. In combination with semiconductor technology tools for device fabrication, these materials
offer unprecedented advantages such as high cooling power density and high speed cooling/heating in
thermal management and high specific power in direct thermal-to-electric power conversion systems.
The improvements achieved with these nanoscale thermoelectric materials and their devices are timely
for meeting many emerging needs in DoD systems as well as in commercial electronic and optoelectronic
systems. As an example, there is an urgent need for compact, high specific power (.1000 W/Kg)
portable power sources based on hydrocarbon fuel sources. Similarly, high power density (.5 W/cm
